Why do post spacing and board gaps matter?

Spacing determines how many posts and sections you need. Board gap affects how many decking boards cover each square foot of deck area.

How much extra decking should I buy?

Add 10% waste for straight runs to cover cuts, defects, and board length mismatches.

Does the drywall calculator include ceilings?

It estimates wall surface area from room perimeter and height. Add ceiling area separately if needed.

Are stair results code-compliant?

The Stair Calculator provides layout math only. Verify riser height and tread depth against local building codes before construction.

SmartMaterialCalc

All Calculators

Lumber Calculators

Estimate decking linear feet, drywall sheets, stair geometry, and structural layout inputs for carpentry and finish projects.

Updated Jun 2026 · 3 calculators · 2 guides

What lumber calculators help you estimate

Carpentry projects need planning estimates for decking, drywall sheets, or stair layout dimensions. These tools translate project measurements into material lists before you visit the lumber yard.

Which calculator should you use?

Each tool matches a specific carpentry or finish task.

Deck Calculator — linear feet of decking boards
Drywall Calculator — sheet count for walls
Stair Calculator — risers, treads, and total run

Common lumber project mistakes

Forgetting board gap when calculating deck coverage
Drywall estimates that ignore ceiling or openings
Stair riser heights that do not divide evenly into total rise
Ordering exact linear feet with no cut waste
Mixing nominal and actual board dimensions

How SmartMaterialCalc estimates lumber materials

Decking uses deck area divided by effective board width including gap. Drywall divides wall area by sheet size with waste. Stairs divide total rise into even riser heights and calculate tread count from your tread depth.