Order more material than the bare measurement so cuts, breakage, and offcuts don’t leave you short. Multiply the needed quantity by a waste factor, then round up to whole units.
The example
500 sq ft + 10% waste.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | Needed | 500 |
| 3 | +10% waste | → 550 |
The formula
The formula:
How it works
How it works:
- Start with the measured quantity needed (area, length, count).
- Multiply by
(1 + waste_percent)to add the allowance — 10% waste is ×1.10. - Wrap in
ROUNDUP(…, 0)so you order whole units — you can’t buy 5.5 sheets. - Typical waste: 10% for flooring/tile, 15% on diagonal layouts, 5–10% for lumber.
Round at the package, not the piece. If material comes in boxes or bundles, convert to packages and round those up: =ROUNDUP(quantity*(1+waste) / units_per_box, 0). Rounding the raw quantity then dividing can still leave you a fraction of a box short.
Try it: interactive demo
Quantity needed and waste %.
Variations
In packages
Boxes/bundles:
Waste amount
Extra units:
Diagonal layout
Higher allowance:
Pitfalls & errors
Round up, never down. ROUNDUP (or CEILING) ensures you never come up short.
Waste as decimal. 10% is 0.10 — check the cell isn’t storing 10.
Package units. Round to the box/bundle size, not loose pieces.
Practice workbook
Frequently asked questions
How do I add a waste factor to a material estimate in Excel?
How much waste should I add?
How do I round to whole boxes?
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