BuilderCalc
Free construction calculators, engineered for accuracy.
Browse by category View all calculators
Concrete & Masonry
Slabs, footings, rebar, brick & block.
Roofing
Pitch, area, shingles & roof geometry.
Framing & Carpentry
Lumber, studs, stairs & rough framing.
Interior Finishes
Paint, drywall, tile & flooring.
Earthwork & Site
Fill dirt, gravel, excavation & topsoil.
Structural
Beams, loads, columns & foundations.
MEP
Electrical, plumbing & HVAC.
Cost Estimators
Project cost, flooring, concrete & build-out.
Most popular calculators View all
Rebar Calculator
Estimate total length, weight and number of bars for a rebar grid.
Concrete Footing Calculator
Calculate concrete volume, bags and cost for strip, pad or pier footings.
Beam Deflection Calculator
Maximum deflection for simply-supported, cantilever or fixed-fixed beams.
Wire Size Calculator
NEC-based wire sizing with ampacity and voltage-drop check.
Fill Dirt Calculator
Volume, weight and truckloads of fill dirt, topsoil, sand or gravel.
Concrete Slab Calculator
Volume, bags and cost for slabs, driveways, patios and floors.
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Why BuilderCalc
Engineered for accuracy
Every formula is sourced from authoritative codes: ACI for concrete, AISC for structural, NEC for electrical. We document the equation behind each result.
Instant, in-browser
All calculations run on your device — no waiting on a server, no inputs ever stored. Works offline once a page is loaded.
Imperial & metric, both
A single toggle switches every input on the page. We auto-detect your region on first visit and remember your choice afterwards.