How to Use Carpet Size Calculator
The Carpet Size Calculator converts a room footprint into both measured area and order area. The distinction matters because carpet installation usually needs trimming, seam allowance, pattern matching and small offcuts around closets or doorways.
- Pick a unit — ft, m, cm or in.
- Enter room length and width.
- Enter waste / overlap % — 10% for straight rooms, more for stairs.
- Read base area in ft² and m².
- Read the waste-adjusted area — the size you should buy.
Formula & Theory — Carpet Size Calculator
The Carpet Size Calculator normalizes length and width to meters, calculates the rectangle area, then converts to square feet. The waste factor is applied after the base area so you can compare the measured room size with the material quantity to order.
areaM2 = lengthM × widthM
areaFt2 = areaM2 × 10.7639
buyArea = baseArea × (1 + waste%)| Situation | Typical waste |
|---|---|
| Simple rectangular bedroom | 5–10% |
| Hallways, closets, door cuts | 10–15% |
| Stairs or patterned carpet | 15–20% |
Assumptions and Limits
The calculator handles one rectangle at a time. For L-shaped rooms, closets or multiple rooms, calculate each rectangle separately and add the order areas. Roll width, seam placement and pattern repeat can change the final purchase quantity, so use installer guidance for high-value jobs.
Use Cases for Carpet Size Calculator
The Carpet Size Calculator is useful for:
- Broadloom orders — Estimate square footage before calling installers.
- Area rug planning — Check whether a rug clears furniture legs properly.
- Padding estimates — Size underlay and moisture barrier from the same base area.
- Budget checks — Multiply order area by price per square foot or square meter.
For stairs or complex floor plans, sketch the room into rectangles first, then add a slightly larger waste allowance.