How this carpet calculator works
Carpet is sold by area, so the job is to work out how much floor your room covers and then buy a little extra. The principle is simple: area = length × width. Measure the room at its longest and widest points, multiply the two together, and you have the bare floor area. From there you add a waste allowance for trimming, doorways and pattern matching, because no fitter lays a carpet to the exact millimetre.
Two conversions make the result useful when you go shopping. First, carpet is frequently priced by the square yard rather than the square foot, and since a yard is three feet, one square yard is 3 × 3 = 9 square feet. Divide your square-foot figure by 9 to get square yards. Second, multiply the area after waste by your price per unit to estimate the cost — just be sure the price and the area use the same unit. The calculator handles both for you and lets you switch between feet and metres.
Reference note: results are a planning estimate. Carpet rolls come in fixed widths — most often 12 ft, but also 13 ft 2 in and 15 ft — so a room that does not match the roll width forces cuts and the leftover strip is usually wasted, meaning your real purchase can exceed the area-plus-waste figure. Underlay, gripper, door bars and fitting are extra. Measure carefully and confirm the roll width and coverage with your supplier before buying.
Square feet to square yards
Because 1 square yard equals 9 square feet, the conversion is just a division by nine. A few common room sizes after a 10% waste allowance:
| Room (ft) | Area (sq ft) | +10% (sq ft) | ≈ Sq yards |
|---|---|---|---|
| 10 × 12 | 120 | 132 | 15 |
| 12 × 15 | 180 | 198 | 22 |
| 14 × 16 | 224 | 247 | 28 |
| 16 × 20 | 320 | 352 | 40 |
Frequently asked questions
- How much carpet do I need?
- Multiply the room length by its width to get the floor area, then add a waste allowance — about 10 percent is typical — for trimming, doorways and pattern matching. Enter your room dimensions above and the calculator returns the area you need in both square feet and square yards, before and after waste.
- How do I convert square feet to square yards?
- There are 9 square feet in 1 square yard, because a yard is 3 feet and 3 × 3 = 9. So divide the area in square feet by 9 to get square yards. For example, 198 square feet ÷ 9 = 22 square yards. Carpet is often sold and priced by the square yard, so this conversion matters when comparing prices.
- How much waste should I add?
- Around 10 percent is a sensible starting point for a simple rectangular room. Add more — roughly 15 percent — for rooms with alcoves, multiple doorways, stairs or a patterned carpet that must be matched across seams, because each of those increases offcuts. The calculator adds whatever percentage you enter on top of the bare floor area.
- Why does roll width matter?
- Carpet is made in fixed roll widths — most commonly 12 feet, with 13 ft 2 in and 15 ft also common — so you cannot buy an exact rectangle. A room narrower or wider than the roll forces a cut from a full width, and the leftover strip is often wasted. That means your real purchase can be higher than the plain area-plus-waste figure, so treat this as an estimate.
- How do I measure a room for carpet?
- Measure the longest length and the widest width of the room, including doorways and any bay or alcove, and round up to the nearest few inches. For an irregular room, split it into rectangles, measure each, and add the areas together. Always measure at the widest points so the carpet is large enough to trim to fit.
- How is carpet priced?
- Carpet is usually sold by the square yard or square foot, with underlay, gripper, fitting and door bars charged separately. To estimate the carpet cost, multiply the area you need — after waste — by the price per unit. Enter a price per square foot or per square yard above and the calculator multiplies it by the area to show an approximate total.