Stair Carpet Calculator

Estimate carpet or runner length to cover stairs (with a little extra for wrapping).

How the Math Works

The Stair Carpet Calculator uses the formula: length = steps × (rise + tread) ÷ 12. This calculation determines the total linear feet of carpet or runner needed for your stairs. Here's how it works: each stair requires carpet to cover both the vertical rise (the height of the step) and the horizontal tread (the depth of the step). By adding these two measurements together, you get the total distance carpet must travel along one step. Multiplying by the number of steps gives the total inches needed, and dividing by 12 converts inches to linear feet, which is the standard measurement for purchasing carpet.

Practical Applications

To use this calculator practically, first measure the rise and tread of your stairs. The rise is the vertical height from the floor to the next step's edge, while the tread is the horizontal depth from the front to the back of the step. Count the total number of steps, or treads, in your staircase. Input these three measurements into the calculator to determine how much carpet you need to purchase. Always add 1-2 extra feet to your final calculation to account for overlap and waste at the landing or beginning of the staircase.

Day-to-Day Use

This calculator saves you time and money when planning a stair carpet project. Instead of guessing or measuring each stair individually, you can quickly determine exactly how much carpet to buy, preventing costly shortages or excess fabric that might not match. Whether you're doing a DIY home improvement project or working with a contractor, knowing the precise carpet length helps you budget accurately and order the right amount on the first try. This is especially valuable when matching patterns or ordering custom runners, where precise measurements prevent expensive mistakes and ensure a professional-looking finish.

Worked example

13 steps, 7" rise, 11" tread × 3 ft → 19.5 ft (~58.5 ft²).

FAQ