Ordering the wrong amount of stair runner is an expensive mistake—too little and you're short at the top or bottom landing, too much and you've wasted money. Here's how to measure correctly the first time.
What You're Measuring
A stair runner covers both the tread (the horizontal part you step on) and the riser (the vertical face between steps). To calculate runner length, you need both dimensions for every step.
Step 1: Measure a Single Step
Measure one step from back to front across the tread, then down the face of the riser to the back of the next tread. Add these two numbers together. This is your per-step runner length.
Standard dimensions to expect:
- Tread depth: 9"–12" (most commonly 10"–11")
- Riser height: 6.5"–8" (most commonly 7"–7.5")
- Combined per step: typically 17"–20"
Don't assume your stairs match standard dimensions—measure at least three steps and compare. Old homes and custom staircases often have inconsistent step sizes.
Step 2: Count Your Steps
Count every step that will be covered. If your runner will extend onto a landing at the top or bottom, measure those separately—landings often need a flat section of runner that doesn't wrap a riser.
Step 3: Calculate the Base Length
Formula:
(Tread depth + Riser height) × Number of steps = Base runner length
Example: 14 steps, each with an 11" tread and 7.5" riser
(11" + 7.5") × 14 = 18.5" × 14 = 259" = approximately 21.6 linear feet
Step 4: Add Overage
Always add overage for three reasons:
- Measurement error: Add 6–12 inches just in case
- Installation tuck: Where the runner wraps around nosings and is tucked under tackless strips, you lose 1–2 inches per step. For 14 steps, this adds another 14–28 inches.
- Pattern matching: If your runner has a repeat pattern, the installer may need to cut from a specific point in the pattern to keep it aligned on each step. Add one full pattern repeat (often 12"–24") to your order.
A safe overage rule: add 15–20% to your base calculation, or at minimum 2 extra feet for a short staircase and 4–5 extra feet for a longer one.
Step 5: Account for Landings
If your staircase has a landing mid-flight (common in L-shaped or U-shaped stairs), measure the landing separately. The runner typically:
- Runs the full length of the landing if it's narrow
- Ends at the landing and restarts at the next flight (installer seams the two pieces)
- Or turns with the staircase, which requires mitered cuts and more material
Ask your installer before ordering how they prefer to handle the landing—seaming vs. mitering affects how much extra material you need.
Runner Width: 27" or 32"?
Most stair runners are sold in 27" or 32" widths. Which you choose depends on your staircase width:
- 27" runner: Standard for staircases 36"–42" wide. Leaves a nice margin of exposed wood on each side.
- 32" runner: Better for staircases 42"–48" wide. Still shows wood on the sides but proportionally wider.
If your staircase is narrower than 36", consider individual treads cut to width rather than a standard runner. If it's wider than 48", you may need a custom-width runner or a wall-to-wall carpet installation.
Quick Calculation Template
Tread depth: _____ inches Riser height: _____ inches Per-step length: _____ inches Number of steps: _____ Base length: _____ inches ÷ 12 = _____ feet Overage (20%): + _____ feet Pattern repeat overage: + _____ feet Total to order: _____ feet
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About RugKnots
RugKnots is a family-owned rug company based in Hagerstown, Maryland. Founded in 2010, we've spent over 14 years helping homeowners and designers find the right rug — from hand-knotted Persian heirlooms to durable machine-made everyday pieces. We hand-inspect every order before it ships, offer free U.S. shipping, and back every purchase with our 30-day return guarantee.
This article was written by our editorial team and reviewed for accuracy. Our writers work directly with our buyers and customer-experience team, who handle thousands of rug questions every year. If you have a question this article didn't answer, reach out — a real human will get back to you within one business day.