Build Calc Pro — Free Construction Calculators
Free professional construction calculators for contractors, builders, and homeowners. No login required, no paywall. Built by a union carpenter with real field experience.
Available Calculators
- Concrete Slab Calculator — Calculate cubic yards, cubic feet, and 80 lb bags for any slab. Includes 10% waste factor.
- Concrete Footing Calculator — Volume for strip and continuous footings.
- Roof Pitch Calculator — Calculate pitch from rise/run, span, or angle. Get compatible roofing materials and pitch factor.
- Roofing Squares Calculator — Calculate squares, bundles, and total roof area with pitch factor and 15% waste.
- Wall Stud Calculator — 16" and 24" on-center stud counts with plates.
- Rafter Length Calculator — Rafter length from span and pitch.
- Room Area Calculator — Floor area, wall area, volume, and paint coverage.
- Drywall Calculator — Sheet count and square footage with 12% waste.
- Brick Calculator — Brick count for walls with mortar joint factor.
- Wire Gauge & Ampacity Calculator — NEC-based wire sizing and voltage drop check.
- Spray Foam Insulation Calculator — Board feet, R-value, kit count for open-cell and closed-cell foam.
- Cellulose Insulation Calculator — Bag count for blown-in attic or wall insulation.
- Triangle Area Calculator — Gable ends and hip roof sections.
Why Build Calc Pro?
Built by someone who spent 3 years as a union carpenter, moved into project management and estimation, then HVAC and insulation residential sales, and now works in digital presence for trades businesses. These calculators use the same formulas contractors use in the field — with real waste factors and trade-accurate results.
Frequently Asked Questions
How do I calculate concrete for a slab?
Multiply length × width × thickness (in feet), divide by 27 for cubic yards. Add 10% for waste. Our concrete slab calculator does this automatically.
What is roof pitch?
Roof pitch is the ratio of vertical rise to horizontal run, expressed as X:12. A 6:12 pitch rises 6 inches for every 12 inches of horizontal distance.
How many board feet of spray foam do I need?
Board feet = square footage × desired thickness in inches. Our spray foam calculator handles open-cell and closed-cell with kit count and cost estimate.