Nobody measures perfectly and no job goes exactly to plan — a tile gets cut wrong, a bag splits open, the subgrade dips in one corner. The waste allowance is the small buffer that keeps those everyday mishaps from turning into a second delivery fee. Here is how to pick the right one for your project.
Step-by-step: choose the right allowance
- Start with the net quantity. Calculate the exact area or volume from your measurements — no waste yet.
- Look at the layout. Straight runs need less extra; diagonal tile, patterned flooring or irregular edges need more.
- Pick a percentage. Use 5% for simple rectangles, 10% as the all-round default, 15%+ for diagonal or complex cuts.
- Apply it in the calculator. Enter the percentage in the waste field — every FG calculator adds it automatically.
- Round up to whole units. Bags, boxes and sheets only sell whole — always round the final number up, never down.
Example calculation
Net: 120 ft² · Waste 15%: 120 × 1.15 = 138 ft².
If pavers cover 1.8 ft² each → 138 ÷ 1.8 = 76.7 → order 77 pavers (or full boxes).
Typical allowances
- Concrete: 5–10% for spillage and uneven subgrade.
- Tile & flooring: 10% straight lay, 15% diagonal.
- Paint: 10% for touch-ups and second-coat variation.
- Drywall: 10–15% depending on ceiling work and openings.
Frequently asked questions
What is a waste allowance, exactly?
The extra percentage you add to your exact material quantity to cover cuts, breakage, spillage and measuring mistakes. If your net need is 100 ft² of tile and you allow 10%, you order 110 ft².
Is 10% waste always enough?
For simple rectangles, usually yes. Use 15% or more for diagonal tile, herringbone patterns, rooms with many corners or irregular outdoor beds. When in doubt, round up — leftover material is cheaper than a second delivery.
What happens if I order with no waste allowance?
You risk coming up short by a box or a bag, which means a second trip or delivery — and new tile or paint may come from a different dye lot that does not match. A small allowance avoids the headache.