How to calculate carpet
Start with the room area, add a waste allowance, then convert to square yards if your supplier prices that way:
Carpet = length × width × (1 + waste %), then square yards = square feet ÷ 9
For L-shaped rooms, split the floor into rectangles, work out each, and add them together. Include closets you're carpeting.
How much waste to add
| Situation | Recommended waste |
|---|---|
| Simple room under 12 ft wide | 10% |
| Room wider than 12 ft (needs seams) | 10–15% |
| Patterned carpet | 15%+ |
| Stairs | 15–20% |
Don't forget
- Padding. You'll need carpet pad for the same area — it's sold separately.
- Roll width matters. Standard rolls are 12 ft wide; wider rooms create seams and waste.
- Tack strips & transitions. Budget for tack strips around the perimeter and transitions at doorways.