Stair Carpet Calculator
Quickly calculate how much carpet you need for your stairs. Enter stair measurements (riser, tread, width, landings) and the tool will return required carpet length, total area and cost estimates.
Stair Details
Stair Nosing
Allowances & Cost
Results — Carpet length, area & cost
How to measure stairs for carpet
Accurate measurements are essential for calculating the right amount of carpet for your stairs. Follow these steps:
- Count the number of steps: Include all steps from top to bottom. Don’t forget any winders or curved steps.
- Measure riser height: Measure the vertical height of one step from top to bottom.
- Measure tread run: Measure the horizontal depth of one step from front to back.
- Measure stair width: Measure the width of the area you want to carpet.
- Note any landings: If you have landings, measure their depth as well.
For best results, measure multiple steps and take averages, as stairs can vary slightly in dimensions.
How It Works
Our stair carpet calculator uses simple, industry-standard formulas to estimate your carpet needs. Here’s the step-by-step process:
Step 1: Convert All Measurements to Common Units
First, we convert all your measurements (riser height, tread depth, width, etc.) to the same unit (inches) so we can work with consistent numbers.
Step 2: Calculate Carpet Needed Per Step
For each step, we calculate how much carpet is needed to cover both the vertical riser and horizontal tread:
Accounting for Stair Nosing
If your stairs have nosing (the overhanging edge):
- Flat nosing: We subtract the nosing thickness since carpet tucks underneath
- Rounded/Bullnose nosing: We add a small amount for the curved shape
- Custom nosing: Use standard calculation unless you provide specific details
Step 3: Calculate Total Carpet Length
We multiply the carpet needed per step by the number of steps, then add any landing areas:
Step 4: Add Allowances for Waste & Fitting
We add extra material to account for:
- Length allowance (8-12% recommended): For pattern matching, seams, and cutting waste
- Width allowance (1-2 inches): For trimming and fitting along edges
Step 5: Calculate Total Area
We multiply the total length (with allowances) by the total width (with allowances) to get the area:
The result is shown in both square feet and square meters for your convenience.
Step 6: Estimate Cost (Optional)
If you provide a carpet price, we calculate the total cost:
Important Note
These calculations provide a reliable estimate for standard straight stairs. For curved, winder, or unusually shaped stairs, we recommend consulting with a professional installer who can account for the additional complexity and waste.