Ordering too little flooring means a second trip, and possibly a box from a different production batch that doesn’t quite match. Ordering far too much wastes money. This flooring calculator gives you the exact floor area, adds a waste allowance for cuts, rounds up to whole boxes and estimates the cost, for one room or a whole floor.
How to use the flooring calculator
- Measure each room wall to wall and enter the dimensions. Use Feet + inches for accuracy.
- Add every area the new floor will cover (closets, hallways, alcoves) with Add to total.
- Set the waste allowance. 10% is a sensible default; see the table below.
- Enter the coverage per box from the product label, for example 22.5 sq ft per carton.
- Enter the price per square foot to see the total. When you give a box size, the cost is based on the full boxes you will actually buy.
How much waste to allow
| Flooring and layout | Typical waste allowance |
|---|---|
| Laminate or luxury vinyl plank, straight | 5–10% |
| Solid or engineered hardwood, straight | 7–10% |
| Tile, straight grid | 10% |
| Tile or plank, diagonal layout | 15% |
| Herringbone or chevron | 15–20% |
| Carpet or sheet vinyl | Depends on roll width and seams – ask the supplier |
Add a little more for small rooms, rooms with many corners or doorways, and very large tiles, which leave bigger offcuts. Many installers also keep one spare box for future repairs.
Working out the number of boxes
Flooring is sold in whole boxes, so the calculator divides the area including waste by the coverage per box and rounds up:
Boxes = (area × (1 + waste %)) ÷ coverage per box, rounded up
With 208.9 sq ft to cover and boxes of 22.5 sq ft, you need 208.9 ÷ 22.5 = 9.28, so you buy 10 boxes.
Worked example: kitchen and hallway
- Kitchen: 13 × 11 ft = 143 sq ft.
- Hallway: 15 × 3.5 ft = 52.5 sq ft.
- Subtract a fitted island the flooring won’t go under: 6 × 3 ft = −18 sq ft.
- Floor area: 143 + 52.5 − 18 = 177.5 sq ft.
- With 10% waste: 177.5 × 1.10 = 195.25 sq ft.
- Boxes of 20 sq ft: 195.25 ÷ 20 = 9.76, so 10 boxes (200 sq ft).
- At $3.29 per sq ft: 200 × 3.29 = $658.00.
Flooring needed for common room sizes
| Room size | Area | +10% waste | +15% waste |
|---|---|---|---|
| 10 × 10 ft | 100 sq ft | 110 sq ft | 115 sq ft |
| 10 × 12 ft | 120 sq ft | 132 sq ft | 138 sq ft |
| 11 × 12 ft | 132 sq ft | 145.2 sq ft | 151.8 sq ft |
| 12 × 12 ft | 144 sq ft | 158.4 sq ft | 165.6 sq ft |
| 12 × 14 ft | 168 sq ft | 184.8 sq ft | 193.2 sq ft |
| 12 × 15 ft | 180 sq ft | 198 sq ft | 207 sq ft |
| 12 × 16 ft | 192 sq ft | 211.2 sq ft | 220.8 sq ft |
| 13 × 15 ft | 195 sq ft | 214.5 sq ft | 224.2 sq ft |
| 14 × 16 ft | 224 sq ft | 246.4 sq ft | 257.6 sq ft |
| 15 × 20 ft | 300 sq ft | 330 sq ft | 345 sq ft |
| 16 × 20 ft | 320 sq ft | 352 sq ft | 368 sq ft |
| 20 × 20 ft | 400 sq ft | 440 sq ft | 460 sq ft |
Tips before you order
- Buy everything at once and check that the batch or lot numbers match, so the colour is consistent.
- Let wood and laminate acclimatise in the room for as long as the manufacturer recommends.
- Check the subfloor is flat and dry; uneven floors can need leveling compound.
- Plan transitions at doorways and where the new floor meets another surface.
- Measure stairs separately: each tread and riser is its own small rectangle.
- Keep a few spare planks or tiles to repair damage later.
Frequently asked questions
How much flooring do I need for a 12×12 room?
A 12 × 12 ft room is 144 sq ft. Adding 10% for waste gives 158.4 sq ft, so with boxes of 20 sq ft you would buy 8 boxes (160 sq ft).
Should I add waste before rounding up to boxes?
Yes. Add the waste allowance to the floor area first, then divide by the coverage per box and round up. The calculator does this for you.
How do I calculate flooring for stairs?
Measure each tread (depth × width) and each riser (height × width), add them up and multiply by the number of steps. Stair nosings are usually bought by the piece, not by area.
Do I need flooring under kitchen cabinets?
Usually not. Most floors are installed up to the cabinets. Floating floors must not be trapped under heavy cabinets or islands, so check the manufacturer’s instructions.
How much does flooring cost per square foot?
It varies widely by material, quality and region, and installation is often priced separately. Enter the price from your quote or the store label to get an accurate total.
Can I measure in metres?
Yes. Choose Metres and the calculator shows the area in square metres as well as square feet. Box coverage is entered in square feet, as printed on most US flooring labels.
Why is my flooring estimate different from the store’s?
Stores may use a different waste percentage or round each room to whole boxes separately. Check that both estimates include the same rooms and the same waste allowance.