Stair Carpet Calculator — Treads, Risers & Methods
Calculate carpet and padding for stairs. Tread + riser per step. Waterfall, cap & wrap, Hollywood.
📋 Quick Examples — Click to Load
Planning estimates only. Verify with a licensed engineer or contractor before construction.
📐 Construction Industry Facts
Standard: 10" tread × 7.5" riser
— IRC
Rolls 12 ft wide
— Industry
Per step: tread area + riser area. Tread = depth × width. Riser = height × width. Add wrap allowance. Waterfall ~10% waste, cap & wrap ~15%, Hollywood ~20%.
Sources: NWFA, Carpet and Rug Institute.
Key Takeaways
- • Per step: Tread + Riser area
- • Waterfall: ~10% waste, fastest
- • Cap & Wrap: ~15% waste, more durable
- • Hollywood: ~20% waste, premium
Did You Know?
How Does Stair Carpet Work?
Area per Step
Tread area = tread depth × width. Riser area = riser height × width. Add 2" wrap per step if wrapping.
Installation Methods
Waterfall: carpet runs over nose. Cap & wrap: each step wrapped. Hollywood: premium finish, most waste.
Landings
Add landing area: size × size × count. Same waste factor applies.
Expert Tips
Installation Methods
| Method | Waste % | Time/step |
|---|---|---|
| Waterfall | 10% | 5 min |
| Cap & Wrap | 15% | 8 min |
| Hollywood | 20% | 12 min |
Frequently Asked Questions
How much carpet do I need for stairs?
Per step: tread area + riser area. Tread = tread depth × width. Riser = riser height × width. Add 10–20% waste depending on installation method.
What is the waterfall method?
Waterfall: carpet runs continuously over the tread nose. ~10% waste. Fastest install. Less durable than cap & wrap.
What is cap and wrap?
Cap & wrap: each step wrapped individually. ~15% waste. More durable, professional look. Better for high traffic.
How much waste for stair carpet?
Waterfall: 10%. Cap & wrap: 15%. Hollywood: 20%. Stairs need more waste than flat rooms due to cuts and wrap.
Do I need padding for stairs?
Yes. Padding extends carpet life and improves comfort. 6–8 lb density typical. Rebond or prime urethane common.
What are standard stair dimensions?
Residential: 10 in tread × 7.5 in riser. Width often 36 in. Commercial: 11 in tread × 7 in riser. Check local building codes.
Key Statistics
Official Data Sources
⚠️ Disclaimer: Waste varies by layout. Verify with installer. Round up when ordering.
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