Deck calculator
Deck Calculator
Estimate deck surface square footage for a rectangular deck area.
Results
- Deck square footage
- 192.00 sq ft
- Square footage including waste
- 211.20 sq ft
Save this calculation to a project estimate.
What this calculator does
This calculator estimates rectangular deck surface square footage from deck length and deck width.
It is useful for early surface-material planning. It does not estimate framing, footings, railings, fasteners, stairs, permits, labor, or structural requirements.
Formula used
Deck square footage equals deck length times deck width. The selected waste percentage is applied to the square footage for a waste-adjusted planning total.
Waste allowance
Waste increases the surface square footage to account for board layout, trimming, board selection, and normal installation loss. Actual ordering depends on board sizes and layout direction.
Scope note
This calculator does not include structural engineering, joist spans, footings, railing, labor, or pricing.
Frequently asked questions
- Does this calculate deck boards?
- No. It calculates surface square footage. Convert that area to boards based on the exact board width, length, spacing, and layout you plan to use.
- Should I include stairs or railing?
- No. Estimate stairs, railing, posts, and framing separately because they use different measurements and materials.
- Why add waste to deck surface area?
- Waste helps account for cuts, board layout, and usable offcuts. It is a planning allowance, not a structural recommendation.