Sizu 
Unit-Price Comparator
Price ÷ quantity across items — cheapest per unit highlighted.
Book 1 · Smart Shopping
Book 2 · Payslip
Marginal Tax & Take-Home
Your own bands → tax, effective rate, marginal rate.
Gross → Net Estimator
Subtract your own deductions (% or fixed) to find take-home.
Hourly ↔ Salary ↔ Overtime
Convert either way, and price up time-and-a-half.
Were You Paid Right?
Rebuild gross from hours & rate; compare with the payslip.
Book 3 · Household Bills
Usage-Cost Calculator
Units × rate + standing charge → bill total & cost per day.
True Annual Cost
Any billing cycle → real yearly total & monthly equivalent.
Tariff Comparison
Two or three plans on the same usage — unit rate plus standing charge.
Estimated vs Actual
Meter readings vs the estimate — over- or under-charged, in money.
Subscription Audit
Annualise every subscription and total the yearly bite.
Fuel vs EV
Cost per mile for petrol vs electric, and the yearly difference.
Book 4 · Mortgage & Loan
Book 5 · Savings & Compound Interest
Compound Interest
Lump sum + monthly saving compounded; growth vs what you put in.
Rule of 72
Doubling time, rate needed, and projected growth.
The Cost of Waiting
What delaying the start really costs by the same end date.
Savings-Goal Planner
The monthly amount to hit a target by a date, interest included.
Rate, Frequency & APY
Turn a nominal rate + frequency into the true yield.
Real vs Nominal Return
Strip inflation out to see real buying-power growth.
Fee Drag
How a small annual fee compounds against you over decades.
It Didn’t Have To Be This Hard · Book 3 · Money Didn’t Have to Be This Hard
Every chapter of this book links to a calculator on this page; the full list is on the book’s page. One is new:
It Didn’t Have To Be This Hard · Book 4 · Statistics Didn’t Have to Be This Hard
Every chapter of this book links to a calculator; the full list, with the worked examples, is on the book’s page. These are new:
Weighted Average
A grade whose parts count differently, and what you need on the last part.
Describe Your Data
Mean, median, quartiles, standard deviation, outliers, histogram and box plot.
Z-Score and Percentile
How unusual is a value? Its z-score, percentile and equivalent on another scale.
Expected Value
What a raffle, bet or warranty pays back on average.
Dice Lab
Roll thousands of dice and watch averages turn into a bell curve.
Bell Curve Areas
The share above, below or between values, or the cut-off for a share.
Random Sample Picker
A fair random sample from any numbered or pasted list.
Margin of Error
A poll’s margin, the margin on a lead, and the sample you need.
Confidence Interval
A range for the true average, with Student’s t for small samples.
Is It Just Luck?
The exact p-value for successes in a number of tries.
A/B Test
Two conversion rates: difference, interval, p-value and power.
Base Rate and False Alarms
What a positive result really means when the thing is rare.
Correlation and Best-Fit Line
Scatter plot, r, r², least-squares line, residuals and predictions.
It Didn’t Have To Be This Hard · Book 5 · Business Numbers Didn’t Have to Be This Hard
Every chapter of this book links to a calculator; the full list, with the worked examples, is on the book’s page. These are new:
Three Profit Levers
What the same change in price, sales or cost does to profit.
Fixed or Variable?
Split a mixed cost from a quiet period and a busy one.
Contribution and Product Mix
Rank products by contribution and by what is scarce.
Break-Even Planner
Break-even, a target profit, the margin of safety and a new price.
Hourly Rate from Billable Hours
The rate you need from the hours customers actually pay for.
Price Change
The extra sales a cut needs, the sales a rise can lose, stacked discounts.
P&L Reader
Margins, every line as a share of sales, and this year against last.
Profit to Cash
From a period’s profit to the change in cash, step by step.
Cash Cycle
Days of stock, days to get paid, days before you pay, and cash freed.
Balance Sheet Ratios
Equity, current and quick ratios, debt to equity and returns.
Depreciation
Straight-line depreciation and the cost per hour of use.
Growth Rate
Changes, CAGR, monthly compounding and real growth.
Order Economics
What one order leaves, and the smallest order that pays.
Customer Value
Churn, lifetime value, acquisition cost and the customer ceiling.
Net Present Value
Today’s value of future amounts, NPV and IRR.
Budget Variance
Price and volume variances and a flexed budget.
Utilisation and Capacity
Billed hours, the bottleneck, and overtime against a part-timer.
Funnel and Mix
How funnel steps multiply, and how the sales mix moves a margin.
It Didn’t Have To Be This Hard · Book 6 · Chance Didn’t Have to Be This Hard
Every chapter of this book links to a calculator; the full list, with the worked examples, is on the book’s page. It also uses Dice Lab, Base Rate and Expected Value above. These are new:
Chance Converter
Any chance as a percentage, “1 in”, odds, and per day, year or lifetime.
Ways Counter
Combinations and arrangements, and the chance of hitting one.
At Least One
Repeated chances, and the tries you need for an even or 90% chance.
Two-Way Table
Every “given” chance from a table of counts, both ways round.
The Long Run
A million dice settling on one in six, 60% heads, and a wheel’s house edge.
Birthday Problem
Shared birthdays, or a shared anything, in a group of any size.
Coincidence Counter
A one-in-ten-thousand day, for you and for a whole town.
Streak Simulator
The exact chance of a run, the average longest run, and a coin to flip.
Three Doors Game
Stick or switch? Play by hand or a thousand rounds at a time.
Survivor Simulator
How many perfect records a crowd produces by luck alone.
Regression to the Mean
Best guess next time, and a league of equally good players.
Lottery Odds
Every prize’s chance, and what a ticket is worth on average.
Warranty and Insurance Check
Price per dollar of cover, break-even, and which excess is cheaper.
Risk Headline Decoder
“Doubles the risk” as counts per 10,000 and the number needed.
Risk Over Time
A yearly or per-trip risk over a lifetime, exactly.
Ruin and Swings
Reaching a target before going broke, swings and doubling systems.
Odds Updater
Change your mind by the right amount: odds × evidence ratio.
Waiting Time
Average waits, yearly risks, random arrivals and collecting a set.
Reliability
Chains, backups, two-out-of-three voting and shared causes.
It Didn’t Have To Be This Hard · Book 7 · Fractions, Decimals and Percentages Didn’t Have to Be This Hard
One calculator for each chapter, each opening on the book’s own worked example, all with exact fraction arithmetic. The full list, with the worked examples, is on the book’s page.
Fraction Picture
Any fraction as bars and a pie, mixed numbers, and a fraction of an amount.
Fraction Compare and Simplify
Which is bigger, by how much, and lowest terms.
Fraction Adder
Add and subtract fractions and mixed numbers over a common bottom.
Fraction Multiplier and Recipe Scaler
Multiply fractions and scale a recipe to any number of people.
Fraction Divider
How many fit, why you flip, and what the leftover is.
Decimal and Fraction Converter
Decimals to fractions and back, with place value.
Decimal Multiplier
Multiply as whole numbers, then count the places back.
Long Division and Repeating Decimals
Every step, whether it ends, and a bill split to the cent.
Rounding and Fair Splitting
Round any way, split so the pennies add up, and round up when you must.
Fraction, Decimal and Percent Converter
Type one, see all three and a hundred-square.
Percent Of and Tip Builder
Any percentage of any amount, built from 10%, 5% and 1%.
Reverse Percent
The price before the discount or tax, and what percent it is.
Percent Change
Change, points, multipliers and the change that undoes it.
Stacked Percentages
Discounts, taxes, coupons and compounding, step by step.
Ratio Splitter
Share any total in a ratio, as amounts, fractions and percents.
Unit Price and Rate Comparer
Per item or per sheet, and fuel savings in gallons.
Proportion and Recipe Scaler
Scale anything, with fixed parts and inverse proportion.
Size Scaler and Pizza Value
Areas, price per square inch, pans and enlargements.
Estimate Checker
A rough answer beside the exact one, to catch slips.
Fair Share Splitter
Bills, rent, nights and settling up, fairly.
Mix and Weighted Average
Weighted grades, blends and the score you need next.
It Didn’t Have To Be This Hard · Book 8 · Your Kid’s Math Homework Didn’t Have to Be This Hard
One tool for each chapter, each opening on the book’s own worked example and drawing the method the way your child is asked to draw it. The full list, with the worked examples, is on the book’s page.
Homework Method Finder
What a worksheet method is called, in the US and the UK, and where it’s explained.
Place Value Explorer
Base-ten blocks, expanded form and renaming a number.
Number Bonds and Make-a-Ten
Ten frames, part-whole models and fact families.
Open Number Line
Add and subtract in jumps; count up, count back.
Column Addition and Subtraction
Partial sums, carrying and exchanging, step by step.
Times Table Strategy Finder
Any fact as an array, with the strategies that build it.
Area Model Multiplier
The box method, partial products, the standard algorithm and lattice.
Partial Quotients and Long Division
Chunking, the bus stop, long division and remainders.
Fraction Wall and Number Line
Equal fractions, ordering and a fraction of a group.
Adding Fractions with Strips
Same-size pieces, mixed numbers and counting up.
Fraction Area Model and How Many Fit
Multiply and divide fractions with pictures.
Decimal Grid and Place Value
Hundred grids, lining up the point, the digits moving.
Bar Model Builder
Any word problem as a bar model, with the steps.
Balance the Equation
Missing numbers, true or false, order of operations.
Rounding and Estimating
On a number line, with the checks that catch slips.
Elapsed Time and Making Change
Time on a number line, clocks and counting up change.
Area, Perimeter and Volume
Rectangles, L-shapes and boxes of cubes.
Pictograph and Bar Graph Maker
Keys, scales, totals and the mean.
Math Facts by Strategy
Gentle practice, one strategy family at a time.
Homework Helper Printables
Ten frames, hundred charts, number lines, squared paper and more.
It Didn’t Have To Be This Hard · Book 8 · Estimation Didn’t Have to Be This Hard
One calculator for each chapter, each opening on the book’s own worked example. The full list, with the worked examples, is on the book’s page.
Rough vs Exact: How Far Off?
Percent off, factor off, and whether it’s close enough.
Round to One or Two Digits
Round, see how far it moved, and balance a product.
Powers of Ten and Scientific Notation
Count the zeros; multiply and divide by powers.
Big Number Feeler
Millions and billions as time, stacks and per person.
Leading-Digit Multiplier
Multiply digits, add zeros; divide by a friendly number.
Fermi Chain Builder
Split a big question into factors you can guess.
Anchor Numbers and Time Converter
The numbers worth carrying, and any rate in any unit.
Bounds and the Middle
Low, high, and the ladder middle between them.
Error Spread Explorer
Why rough guesses multiplied together land close.
Unit Chain Converter
Conversions as a chain of factors that cancel.
Time Adder: Per Day to Per Year
Daily minutes to yearly hours, lines and to-do lists.
Daily, Hourly, Yearly and Doubling
Pack vs single, × 365, × 2,000 and the rule of 72.
Area, Volume and Fill Estimator
Paces, mulch, paint, water and boxes.
Sample-and-Scale Counter
Crowds by area, visits over a day, samples scaled up.
Doubling and Halving Time
Rule of 72 against the exact time, and doublings counted.
Per-Person, Per-Day Sense Check
Spread a claim over people, days and minutes.
Claim Checker
Six checks for numbers that can’t be true.
Range Combiner
Add and multiply ranges; see if two overlap.
Three-Point Project Estimator
Low, likely, high, corrected by your track record.
Market Sizing Builder
Top-down and bottom-up, the middle, per person.
Earth-Scale Calculator
Walk the world, light to the Moon, the weight of the air.
Book 6 · Budget
Whole-Picture Budget
Take-home − savings − bills − debt − discretionary = surplus.
Income Allocation Grid
Split take-home by percentage — and check the shares hit 100%.
Irregular-Cost Converter
Yearly and occasional bills → the monthly amount to set aside.
Variable-Income Budget
Budget on the floor, bank the good months, build a reserve.
Debt-Service Ratio
Debt ÷ take-home, your ceiling, headroom, and does-a-loan-fit.
Savings Rate
Saved ÷ take-home, the gap to target, pay-yourself-first.
Work & Money · Book 1 · Small-Business
True Unit Cost
Variable cost plus a fair share of fixed costs = the real cost of one unit.
Markup ↔ Margin
Flip between the two, and price to a target margin.
Price for Profit
True cost + target margin → the price, and the floor you can't cross.
Break-Even
Fixed ÷ contribution = units to sell, revenue, and margin of safety.
Cash Runway
How long your cash lasts at your monthly burn.
Tax Set-Aside
Park the right share of profit — you pick the rate.
Cost of a Discount
New contribution and the extra volume a markdown really needs.
Work & Money · Book 2 · Side-Hustle
Real Hourly
Payout − costs ÷ every minute (active + wait + drive + admin) = your true rate.
Platform-Fee Take-Home
Listing + commission + payment + withdrawal — see what actually lands.
Mileage Deductible
Miles × per-mile rate — the honest running cost of your car.
Hobby vs Business Check
Four rough tests — regularity, motive, scale, presentation.
Quote from Target Hourly
Work backwards from what you want to keep to the price to send.
Scale, Keep, or Cut
Marginal hourly of the next hour vs its honest opportunity cost.
Boost / Promoted-Listing Break-Even
How many extra sales the boost must truly cause to pay for itself.
Math Workout · Book 1 · The Everyday Math Workout
Percent Calculator
X% of a number, X is what % of Y, and percent change from one figure to another.
Fraction Calculator
Add, subtract, multiply, or divide two fractions — mixed numbers supported. Result reduced.
Mental-Math Drill
A 30, 60, or 90-second timed round of shortcut-friendly problems, with scoring at the end.
Ratio & Proportion Solver
Solve a : b = c : d for any missing term, or scale a recipe from N servings to M.
Equation Solver
Type a·x + b = c and see each isolation step, plus a check on the answer.
Unit Converter
Length, weight, volume, and temperature — metric and US customary, exact factors.
Mean / Median / Mode / Range
Paste a list of numbers and get all four at once, with a short explanation of each.
Math Workout · Book 2 · The Money Math Workout
Paycheck & Earnings
Convert hourly ↔ weekly ↔ biweekly ↔ monthly ↔ annual, plus overtime and take-home.
Whole-Picture Budget
Take-home − savings − bills − debt − discretionary = surplus, on one page.
Compound Interest
Lump sum + monthly saving compounded; growth vs what you actually put in.
Debt Payoff
Months to zero, total interest, and avalanche-vs-snowball ordering for several debts.
Unit-Price Comparator
Price ÷ quantity across items — the pack that's genuinely cheaper per unit.
Marginal Tax & Take-Home
Your own bands → tax, effective rate, and the marginal rate on your next dollar.
Break-Even
Fixed costs ÷ contribution per sale — the point where a decision pays its own way.
Math Workout · Book 3 · The Kitchen Math Workout
Fraction Calculator
Add, subtract, multiply or divide two fractions — mixed numbers in, reduced fraction out.
Kitchen Unit Converter
Cups, tablespoons, teaspoons, millilitres, grams, ounces, and °F ↔ °C with exact factors.
Recipe Scaler
Scale by servings; amounts come back as kitchen fractions, salt and leaveners held back.
Nutrition Label
Correct the label for what you really ate, cross-check the 4-4-9 macros, compare per 100 g.
Unit-Price Comparator
Price ÷ quantity across items — the can, jar or bag that's genuinely cheaper per unit.
Cooking Time & Temperature
Work backwards from serving time to a start time per dish; convert the oven dial both ways.
Mental-Math Drill
Timed practice on the halving, doubling and 10% shortcuts the chapter teaches.
Math Workout · Book 4 · The Garden Math Workout
Garden Area
Add rectangles, triangles and circles, subtract the patio and pond, get net growing area.
Soil & Mulch Volume
Cubic feet, cubic yards and bag counts, then bags priced against a bulk delivery.
Plant Spacing & Counts
Rows, plants per row, the square-foot cross-check, and seeds to buy at your germination rate.
Harvest Yield Planner
Work back from the jars you want to the plants you need, waste allowance included.
Growing Season Planner
Frost dates to season length, seed-starting dates and a succession-sowing schedule.
Container & Pot Volume
Gallons a pot holds, its weight when wet, and whether the balcony can take the load.
Mental-Math Drill
Timed practice on the estimation shortcuts the chapter teaches.
Math Workout · Book 5 · The Work Math Workout
Markup ↔ Margin
Convert either way, price back from a target margin, and see what a discount really costs.
Percentage Change
Change between two values, several changes chained, and points kept apart from percent.
Break-Even
Break-even in units and revenue, and what moves it when price or cost shifts.
Gross-to-Net Pay
Walk a gross figure down through tax, FICA, insurance and retirement to take-home.
Chart Check
The same numbers on an honest axis and a truncated one, so you can see the real gap.
Mean, Median, Mode & Range
All four at once, outliers flagged, and weighted averages done properly.
ROI & Payback
Return, payback period and the trade-off between them, for one option or two.
Accounting Made Fun & Easy · Book 1 · Read the Numbers
Profit → Cash Reconciler
Net profit + depreciation − rise in receivables + rise in payables = operating cash.
Statement Tie-Out Checker
Confirm the wires agree — profit to equity, and ending cash to the balance sheet.
The 5-Minute Fast-Scan
The six looks in order, then hunt the four first tells on any set of accounts.
Accounting Made Fun & Easy · Book 2 · Spot the Cooked Books
Benford's-Law Tester
Paste a set of figures and see whether the leading digits climb the natural staircase — or break it.
Too-Smooth Returns Detector
Drop in a run of monthly returns and see how suspiciously flat they are next to a real market.
The Ratio Red-Flag Kit
The Detective's Fast-Scan — nine ratios and the numbers each one is trying to tell you.
Accounting Made Fun & Easy · Book 3 · Don't Get Fooled
Too-Good-Return Checker
Annualise any monthly return, run the rule of 72, and see whether a "12%/month" pitch is even possible.
Subscription Audit
List every recurring charge and see the annual damage. The small leaks add up faster than you think.
APR & True-Cost Checker
Turn a "$45 fee for two weeks" into an APR, and a "cheap monthly" into what it actually costs.
Make & Machine · Book 1 · Woodworking Math: Cut It Once
Board Feet & Cost
Board feet and cost, nominal vs. actual, whole shopping lists of boards.
Sheet Yield & Kerf
Kerf-aware nesting: parts in, strip layout and yield out.
Squaring & the Diagonal Check
Diagonals in, lean out; scales a 3-4-5 to any legs.
Even Spacing
Divides a span, with running positions to mark from one end.
Joints by Proportion
Every joint from one stock thickness, plus side-grain glue area.
Mitre & Saw Setting
Saw setting for any n; long point ↔ short point at any angle.
Compound Angles
Two splays in, resultant, sightline, both saw settings, leg length.
Shelf Deflection
Deflection, with the span ÷ 360 line marked.
Finish Coverage
Cabinet dimensions → surface area → litres.
Wet & Dry Film Build
Coverage and solids → wet film, dry film, coats, spray passes.
Project Cost & Payback
The whole roll-up, and the four-line ledger.
Make & Machine · Book 2 · Maker Electronics Math
LED Resistor & E12 Value
The resistor to fit, the one you can buy, and the current you really get.
Capacity, Watt-Hours & C-Rate
Series and parallel packs, a usable derate, and the C-rate a load asks for.
The Battery Budget
The one to bookmark. Every line of your design, and its share of the battery.
Divider & What It Costs
Output, loading, source impedance, and the yearly bill if nobody switches it off.
Volts, Counts & Resolution
What one step is worth — and why fine is not the same as true.
Two-Point Calibration
Slope and offset from two known points, and an error bar you can defend.
τ, Settling & Debounce
How long to wait before reading, and what the waiting costs.
Pull-Ups & Always-On Loads
What a load costs per year once you say how long it is connected.
Duty, Average & Brightness
A quarter of the current does not buy a quarter of the light.
Regulator Heat & Quiescent
The two bills a regulator sends, and buck against linear for your interval.
Storage Days & Sending
Which runs out first, the battery or the memory — and what a radio costs.
Event Runtime & Dosing
Runtime when the world decides how often, plus stall current.
Shunt & Prediction Check
Measure a current your meter cannot read, then explain the gap.
Ohm’s Law Solver
Any two of volts, milliamps, ohms and milliwatts — and the other two.
Series & Parallel Resistors
Combine resistors, and find the E12 value you can actually buy.
Battery Pack Builder
Cells in series and parallel — volts, usable mAh, and days.
Wake Interval Sweep
Runtime at every interval, and where waking less often stops paying.
Hours Past a Threshold
Readings past a line, turned into hours below freezing or above damp.
mA, mAh, mA·s & Time
The unit conversions every battery sum in the book turns on.
Craft & Studio · Book 1 · Vegan Baking & Pastry Math
Cups to Grams, Honestly
The range a cup recipe really covers — not one flattering number.
Baker's Percentage, Both Ways
Formula to grams for any dough weight, with a misprint check.
Hydration & Rescue
Read it, change it, and put a too-wet dough right — salt and yeast included.
Pan Scaler & Focaccia Dough
The dough your pan wants, and the factor between any two pans.
Levain & Preferment
The final mix with nothing counted twice, and a feed by ratio.
Dough Temperature & Water Blend
The water sum, then the grams of kettle, tap and ice to make it.
Bake Schedule, Backwards
From when you want to eat to when you must start — across midnight.
Bake Loss & Dividing
Dough for a promised weight, baguettes by length, overlapping cuts.
Oven Converter & Bake Cost
°C, °F, gas mark and fan with your oven's offset, and the electricity.
Plant Swaps by Ratio
Butter, egg and honey replaced — and the water each swap adds.
Lamination Planner
Layers for any folds, the fat block, and a sheet cut into triangles.
Loaf Cost, Margin & Break-Even
What a bake costs, what a price leaves, and a market day added up.
The Bake Day Planner
The one to bookmark: four formulas sized to your pan, on one sheet.
Home & Build · Book 1 · Home Renovation Math: Measure the Room, Not the Guess
Paint & Tin Sizes
Net area, coats and coverage rate in — litres, the tin to buy, and the leftover.
Room Survey: True Area & Diagonal Check
Two widths and a depth in — true area, order area, and how far out of square you are.
Waste, Packs & the Order
Area, waste % and a pack's coverage in — whole packs to buy, and the real spare.
Rows, Borders & the Rebalance
Span and board width in — full rows and a matched edge row each side, never a sliver.
Centres, Stock Lengths & Screws
Span and centres in — batten count, then screws per m² for a whole wall.
Coverage Rates & Grout
Area and thickness in — bags to buy, plus a tile-by-tile grout calculator.
Field-Check, Mitres & Rakes
A 500 mm arm-check in — the real corner angle and the mitre setting.
Openings: Doors, Architrave & Windows
A door leaf in — lining, structural opening, architrave, fixing depth, window board and blind.
Will It Fit?
Floor build-up against a door gap, furniture against a walkway, a room drawn to scale.
Decode a Quote
Gross and tax rate in — the net figure, honestly, plus two quotes compared.
The Whole Room: Cost & Payback
Materials and a builder's quote in — the saving, and what your time was worth.
Built by Numbers · Book 1 · Walls That Stand
Block and Brick Counter
Any wall, any block or brick, counted two ways — joint included, waste added, cuts flagged.
Set-Out: Square, Level and Stepped
3-4-5 diagonals, a rectangle checked, a fall turned into a slope, and footing steps.
Footing Concrete
Dig, pour, and the real choice: 77 heavy bags or one small truck.
Pick Your Wall
Cost per meter, and cost per meter per year of life, for every route you price.
Mortar: How Much, and How Much at Once
Bags, the same answer by volume, mix-your-own, and the right batch size.
Wind on a Wall, Bars and Grout
The square law, the published bar spacing, and the grout to fill the cores.
How Hard Water Pushes
½ρgh² per meter, where it acts, and the push on a whole wall and a gate.
The Rain That Falls Inside
A flood wall keeps rain in too: liters an hour, and whether the pump keeps up.
Render and Paint
Both faces and the ends: bags of base and finish coat, and gallons of paint.
The Shopping List
Quantity, waste, order, price and total for every material.
The Weekend Plan
Saturday and Sunday, hour by hour, with the waits written in.
The Set-Out Sheet
The line, the 3-4-5 corners and the fall of the ground.
Built by Numbers · Book 2 · Fences That Stand Straight
Fence Post Counter
Bays and posts for any run, open or closed, with the real spacing and a gate.
Fence Set-Out
Post centers from one zero, 3-4-5 corners at any size, and the slope as a percent, an angle and inches per foot.
Post Holes and Concrete
Post length, hole volume, bags of concrete per hole and in all, gravel, and the weight you are moving.
Pick Your Fence
Every fence type by cost per foot and per meter, and cost per year with your own life estimate.
Pickets, Gaps and Boards
Equal gaps between posts or on a gate, the picket count for a target gap, and boards on a long run.
Up and Down the Slope
Racked or stepped: the fall per bay, rail length and cut angle, and the triangles under a stepped panel.
A Fence Is a Sail
Wind pressure by speed, the push on one post, and what spacing and height do to it.
The Gate That Stays Square
Gate width from the opening, the brace length and angle, the gate's weight and the pull on the top hinge.
Finish That Lasts
Area to finish, gallons for your coats, and the cost per year of each kind of finish.
The Shopping List
Quantity, spare, order, price and total for every material.
The Weekend Plan
Two weekends, job by job, with the waits for concrete and stain written in.
The Set-Out and Cutting Sheet
The line, post centers from one zero, a 3-4-5 corner and the cutting list.
Every calculator here runs arithmetic the books teach you to do by hand — they back the books up, they don’t replace them. Each cites its chapter, keeps your figures in your browser, and never sends them anywhere.