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Square Footage

Length × Width = Area

For irregular rooms, break into rectangles and add the results.



Concrete Volume

Slab volume & bag count

Order 5–10% extra for waste. 60 lb bag ≈ 0.45 cu ft — 80 lb bag ≈ 0.60 cu ft.



Board Feet

(Thickness × Width × Length) ÷ 12

Use nominal dimensions (e.g., a 2×4 is entered as 2 in × 4 in).



Paint Coverage

Gallons needed for a surface

Most interior paints cover 350–400 sq ft/gal. Check your paint's label. Calculate each surface separately and add them together.



Roofing

Squares & bundles of shingles

1 square = 100 sq ft. 3 bundles per square (standard 3-tab). Use 10% waste for simple roofs, 15% for complex or steep roofs.



Stud Spacing

Number of studs for a wall

Includes the end stud. Add extra for corners, headers, and openings. Common spacings: 16" OC (standard) or 24" OC (advanced framing).



3-4-5 / Right Triangle

Solve any side — or generate 3-4-5 multiples

Enter a multiplier and click APPLY 3-4-5 to get the side lengths (e.g. multiplier 2 → 6, 8, 10). Or enter any two sides to solve for the third using the Pythagorean theorem.