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Construction Calculators

Concrete, framing, electrical, HVAC, structural, and landscaping calculations for builders and DIYers.

28 free calculators · No signup required

What Are Construction Calculators?

Material estimates, cost calculations, and structural measurements for real building projects. I built these because nothing's worse than being at the supply store doing math on the back of a receipt — or ordering 20% too little concrete and finding out when the truck's already poured half the slab.

From concrete volumes to beam deflection, every tool uses industry-standard formulas and building code references (IRC, ASCE 7, NEC). Whether you're a contractor running a job or a homeowner tackling a weekend project, these calculators give you the numbers you need before you cut the first board.

Concrete & Materials

Cubic yards, bag counts, and cost estimates for concrete slabs, footings, and columns. Built-in waste factors and rebar spacing so your material order is right the first time.

Structural

Wind loads, snow loads, and beam deflection using ASCE 7 and standard engineering formulas. The kind of math you need when pulling permits or verifying structural specs.

Mechanical & Electrical

HVAC sizing, wire gauge selection, and pipe flow calculations for plumbing and fire protection. NEC-based where applicable.

Landscaping & Site Work

Soil amendment volumes, fill dirt quantities, and grading calculations for outdoor and site work projects.

More Construction Calculators

Frequently Asked Questions

How many bags of concrete do I need?
Figure out cubic feet first (length × width × depth in feet), then divide by the bag yield. An 80-lb bag covers about 0.6 cubic feet. So a 4×4 ft slab at 4 inches deep = 5.33 cu ft = 9 bags. Always add 10% for waste — you'll use it.
What size wire do I need?
It depends on amperage, run distance, voltage, and how much voltage drop is acceptable. For a typical 20A circuit under 50 feet, 12 AWG works. Longer runs or higher amperage mean stepping up to a larger gauge. The Wire Gauge Calculator factors in NEC requirements automatically.
How do I calculate wind load?
Wind load follows the ASCE 7 formula: qz = 0.00256 × Kz × Kzt × Kd × V² × I. You need your local design wind speed (from building code), exposure category (terrain type), building height, and importance factor. The calculator handles all the coefficients — you just plug in your project specifics.
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Pool Volume Calculator
Gallons for any pool shape.
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Rebar Calculator
Rebar spacing, quantity, and weight for concrete.
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Stair Calculator
Rise, run, and code compliance.