Door & Window Trim Length
A door-type opening (open at the bottom) is trimmed on three sides; a window is trimmed on all four. A cutting-loss margin is added on top.
Your numbers
Total trim needed
6.6m
Trim per opening
6m
Formula
Total trim needed = 2×(Opening width (cm)+Opening height (cm)) × Openings ÷ 100 × (1+Waste allowance÷100)
Trim is sold in fixed lengths (2.4 m, 3 m). Divide this total by that stock length and round up for the real order quantity.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Opening width (cm) (cm) | 90 | 20 and up |
| Opening height (cm) (cm) | 210 | 20 and up |
| Openings | 1 | 1 ~ 50 |
| Trimmed on all sides (1=window/0=door) | 1 | 0 ~ 1 |
| Waste allowance (%)The extra bought to cover breakage and offcuts. | 10 | 0 ~ 30 |
Step by step
Quick reference table
Results when only Opening width (cm) (cm) changes and everything else stays put.
| Opening width (cm) (cm) | Total trim needed (m) | Trim per opening (m) |
|---|---|---|
| 45 | 5.6 | 5.1 |
| 67.5 | 6.1 | 5.55 |
| 90 | 6.6 | 6 |
| 135 | 7.6 | 6.9 |
| 180 | 8.6 | 7.8 |
What each result means
| Result | At default values |
|---|---|
| Total trim needed (m)Trim per opening times the opening count, plus a cutting-loss margin. | 6.6 |
| Trim per opening (m)The perimeter trimmed on a door (3 sides) or window (4 sides). | 6 |
Common mistakes
Trim is sold in fixed lengths (2.4 m, 3 m). Divide this total by that stock length and round up for the real order quantity.
Glossary
- Waste allowance
- The extra bought to cover breakage and offcuts.
- Total trim needed
- Trim per opening times the opening count, plus a cutting-loss margin.
- Trim per opening
- The perimeter trimmed on a door (3 sides) or window (4 sides).
Frequently asked questions
QHow is Door & Window Trim Length calculated?
Total trim needed = 2×(Opening width (cm)+Opening height (cm)) × Openings ÷ 100 × (1+Waste allowance÷100) — A door-type opening (open at the bottom) is trimmed on three sides; a window is trimmed on all four. A cutting-loss margin is added on top.
QCan you walk through an example?
With Opening width (cm) 90cm, Opening height (cm) 210cm, Openings 1, Trimmed on all sides (1=window/0=door) 1, Waste allowance 10%, the answer is Total trim needed 6.6m.
QWhat do I need to enter?
Enter Opening width (cm), Opening height (cm), Openings, Trimmed on all sides (1=window/0=door), Waste allowance. The result recalculates as you type, and an empty box counts as zero.
QHow much does the answer move if I change a number?
Changing only Opening width (cm) (cm) moves the answer to Opening width (cm) (cm) 45 → Total trim needed (m) 5.6 and Opening width (cm) (cm) 180 → Total trim needed (m) 8.6. The table below lays out five steps.
QHow are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
QAnything to watch out for?
Trim is sold in fixed lengths (2.4 m, 3 m). Divide this total by that stock length and round up for the real order quantity.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.