Free tool
Material waste calculator - how much should you buy?
Enter the quantity and the waste percentage, and the calculator works out how much to buy and how many whole packs that is. Choose a material to get a guideline waste percentage.
Guideline 5-10%. More cuts with many corners and penetrations.
The area, length or number of items to cover.
Cost price excl. VAT.
What to buy
- Net quantity
- 24 m²
- Waste (7.5%)
- 1.8 m²
- To buy
- 25.8 m²
- Whole packs of 1.44 m²
- 18 packs (25.92 m²)
- Material cost excl. VAT
- DKK 7,774.70
All amounts are excl. VAT unless stated otherwise. The calculation runs in your browser - nothing is sent or stored.
The formula
Waste = quantity × waste % / 100
To buy = quantity × (1 + waste % / 100)
Packs = to buy / content per pack, rounded up
Waste is added on top of the net quantity - 10% waste on 20 m² means 22 m². The price is calculated on what you actually buy, i.e. the whole packs.
Worked example
A 24 m² floor is to be tiled in a straight lay. You allow 7.5% waste, and the tiles are sold in packs of 1.44 m² at DKK 299.95 per m².
Waste = 24 × 7.5 / 100 = 1.8 m²
To buy = 24 + 1.8 = 25.8 m²
25.8 / 1.44 = 17.92 → 18 packs = 25.92 m²
25.92 × 299.95 = DKK 7,774.70 excl. VAT
Typical waste percentages per material
The ranges are guideline rules of thumb, not fixed standards. Use the low end for large, rectangular rooms and the high end for small rooms, many corners, angled cuts and patterns that must match.
The manufacturer's instructions and data sheet always take precedence - especially for consumables such as paint, adhesive and grout, where the consumption per m² is on the pack.
| Material | Waste | Note |
|---|---|---|
| Tiles, straight lay | 5-10% | More cuts with many corners and penetrations. |
| Tiles, diagonal or herringbone | 10-15% | Angled cuts along every edge mean more waste. |
| Laminate and parquet | 5-10% | Herringbone and small rooms sit at the high end. |
| Plasterboard | 5-10% | Sloping ceilings and many openings mean more waste. |
| Timber, boards and cladding | 10-15% | Depends on lengths, knots and joints. |
| Insulation (boards and rolls) | 5-10% | Fitting between studs and rafters. |
| Wallpaper | 10-20% | Pattern matching can mean more than 20%. |
| Bricks | 5-10% | Incl. broken bricks and cutting. |
| Paint | 5-10% | Work out consumption from the manufacturer's m² per litre. |
Build the whole quote with your own prices
The calculator works out one number. Calco works out the whole quote: materials from your wholesaler's price file, your hourly rates and your markup, VAT and total - ready to send with a link the customer can accept online.