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19 free calculators

Calculators for the field

Quick math for concrete, electrical, plumbing, HVAC, framing, solar, and crew hours. Every one shows the formula and runs in your browser.

Concrete & Civil

4 calcs

Concrete Calculator

Cubic yards and bag counts for slabs, footings, and round columns.

Rebar Grid Calculator

Bar count, linear feet, sticks, and weight for a slab grid.

Gravel, Base, and Asphalt Tonnage Calculator

Cubic yards and tons of gravel, base, sand, or asphalt.

Excavation and Truckload Calculator

Bank yards, loose yards after swell, and truckloads.

Electrical

4 calcs

Ohm's Law and Power Calculator

Enter any two of volts, amps, ohms. Get the rest plus watts.

Voltage Drop Calculator

Volts and percent drop for copper or aluminum, 1 or 3 phase.

Conduit Fill Calculator (EMT, THHN)

Percent fill and smallest EMT for THHN wire.

kW to Amps Calculator

Amps from kW for single or three phase loads.

Plumbing

2 calcs

Pipe Volume and Water Weight Calculator

Gallons in a pipe run and what the water weighs.

Pipe Slope and Fall Calculator

Total fall for a drain run at 1/8, 1/4, or 1/2 inch per foot.

HVAC

2 calcs

BTU and Tonnage Rough Sizing Calculator

Ballpark BTU, tons, and kW from square feet.

CFM and Air Changes Calculator

CFM needed for a target air changes per hour.

Framing & Drywall

2 calcs

Wall Stud and Plate Calculator

Studs and plate footage for a wall at 16 or 24 in O.C.

Drywall Sheets, Mud, and Tape Calculator

Sheet count plus rough mud and tape amounts.

Solar & BESS

3 calcs

Solar Array Size Calculator

Array kW and panel count from daily kWh and sun hours.

Battery Storage Size Calculator

Battery kWh from load, backup hours, and depth of discharge.

Solar String Voltage Calculator (Cold Temp)

Cold-corrected Voc and max modules per string.

General & PM

2 calcs

Crew Hours and Labor Cost Calculator

Man-hours, overtime, and labor cost for a crew.

Production Rate and Crew Days Calculator

Man-hours and crew days from quantity and production rate.

These are estimates. Check them against the plans, code, and your super before you order or build.

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