Door, Architrave & Window Calculator

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Door leaf & lining

Leaf width mm

Leaf height mm

Side gap, each mm

Head gap mm

Floor gap mm

Lining timber thickness mm

Fitting tolerance, each side mm

Architrave

Margin beyond the lining mm

Architrave width mm

Architrave stock length mm

Fixing depth, optional

Skim thickness mm

Board thickness mm

Grip needed in timber mm

Window board & blind, optional

Window opening width mm

Board overhang (ear), each end mm

Reveal board thickness mm

Reveal depth after lining mm

Board nose beyond the wall mm

Blind clearance inside the reveal mm

Blind overlap outside the opening, each side mm

Enter the door leaf size, then press Calculate.

From the book — Chapter 8. Clear lining = leaf + gaps. Structural opening = clear lining + 2×(lining timber + fitting tolerance). Architrave leg = clear height + margin + architrave width; head = clear width + 2×(margin + architrave width).

Matches Chapter 8's door, architrave and window workings exactly. Everything stays in your browser — no sign-up, nothing stored.