How to use this flooring calculator
- Pick the material and layout. The layout sets a typical waste allowance, which you can change.
- Enter each room. Use Add another room for extra rooms, closets or the two halves of an L-shaped room.
- Enter the coverage per box printed on the packaging. Not needed for carpet.
- Optionally add underlayment roll coverage, the room perimeter for baseboard or skirting, and a price.
Flooring formulas
Area to buy = Area × (1 + Waste % ÷ 100)
Boxes = Area to buy ÷ Coverage per box, rounded up
Carpet (sq yd) = Area to buy (sq ft) ÷ 9
Baseboard = (Perimeter − Doorways) × 1.10
When you enter a price per square foot or square metre, the cost is based on the whole boxes you actually buy, not just the floor area.
Worked example: laminate in a 15 × 20 ft living room
- Floor area: 15 × 20 = 300 sq ft
- With 10% extra: 300 × 1.10 = 330 sq ft
- Boxes covering 20 sq ft each: 330 ÷ 20 = 16.5, so buy 17 boxes (340 sq ft)
- At $2.50 per sq ft: 340 × 2.50 = $850
- Underlayment in 100 sq ft rolls: 300 ÷ 100 = 3 rolls
- Baseboard: a 70 ft perimeter minus 6 ft of doorways is 64 ft, plus 10% = 70.4 ft, so 9 pieces of 8 ft
Metric example: vinyl plank in a 4 × 5 m bedroom
- Floor area: 4 × 5 = 20 m², or 22 m² with 10% extra
- Boxes covering 2.2 m² each: 22 ÷ 2.2 = exactly 10 boxes
- Skirting: 18 m perimeter minus a 0.9 m door is 17.1 m, plus 10% = 18.81 m, so 8 lengths of 2.4 m
Boxes needed for common room sizes
With 10% extra. Box coverage varies by product, so these are examples only.
| Room | Area | With 10% | 20 sq ft boxes | 24 sq ft boxes |
|---|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 110 sq ft | 6 | 5 |
| 12 × 12 ft | 144 sq ft | 158.4 sq ft | 8 | 7 |
| 12 × 15 ft | 180 sq ft | 198 sq ft | 10 | 9 |
| 15 × 20 ft | 300 sq ft | 330 sq ft | 17 | 14 |
| 20 × 20 ft | 400 sq ft | 440 sq ft | 22 | 19 |
| 20 × 25 ft | 500 sq ft | 550 sq ft | 28 | 23 |
| Room | Area | With 10% | 2 m² boxes |
|---|---|---|---|
| 3 × 3 m | 9 m² | 9.9 m² | 5 |
| 3 × 4 m | 12 m² | 13.2 m² | 7 |
| 4 × 5 m | 20 m² | 22 m² | 11 |
| 5 × 6 m | 30 m² | 33 m² | 17 |
Waste allowance by layout
| Layout | Typical extra |
|---|---|
| Straight, parallel to the longest wall | 5–10% |
| Straight in a room with many corners or closets | 10–15% |
| Diagonal | 15% |
| Herringbone or chevron | 15–20% |
| Carpet (seams and pattern matching) | 10% or more |
Common starting points only. Your installer or the product instructions may recommend more.
Tips before you buy flooring
- Measure every room separately, including closets, and add them up. Rough “whole floor” guesses often fall short.
- Leave an expansion gap. Floating floors such as laminate and many vinyl planks need a small gap around the edges, which the baseboard or skirting covers. Follow the manufacturer’s gap size.
- Check the subfloor. Most products need a flat, dry, clean subfloor. Moisture is a common cause of failed floors, so check whether you need a vapour barrier.
- Buy one batch. Order everything at once so colour and finish match, and keep a spare box for repairs.
- Mix planks from several boxes as you lay them, so colour variation spreads evenly across the room.
Tiling instead? Use our tile calculator. For a quick room area, try the square footage calculator.
Frequently asked questions
How many boxes of laminate do I need for a 12x12 room?
A 12 × 12 ft room is 144 sq ft. With 10% extra for cuts that is 158.4 sq ft, so with boxes that cover 20 sq ft you need 8 boxes, or 7 boxes if each covers 24 sq ft. Box coverage varies a lot by product, so always use the figure on your box.
How much extra flooring should I buy?
About 10% for a straight layout is a common rule. Go up to around 15% for diagonal installs or rooms with many corners, and 15–20% for herringbone or chevron. Very small rooms often need more, because each cut wastes a bigger share of a plank.
How do I convert square feet to square yards for carpet?
Divide square feet by 9. A 15 × 20 ft room is 300 sq ft, which is 33.3 sq yd, or about 36.7 sq yd with 10% extra. Carpet comes in fixed roll widths, so the real amount can be higher once seams and pattern matching are planned. A carpet fitter will measure precisely.
Do I need underlayment for laminate or vinyl plank?
Laminate is usually laid over a foam or felt underlayment. Many vinyl planks and some laminates have underlayment already attached, and adding a second layer can void the warranty. Check the product instructions before buying any.
How do I work out how much baseboard or skirting I need?
Measure the length of every wall (the room’s perimeter), subtract doorways, then add about 10% for mitre cuts and offcuts. Divide by the length of one piece and round up to get the number of lengths to buy.
Should flooring acclimatise before installing?
Many wood and laminate products ask you to leave the unopened boxes in the room for a period, often around 48 hours, so they adjust to the temperature and humidity. Follow the time given by the manufacturer for your product.
Last reviewed November 5, 2026.