Engineering

Free Engineering & Construction Calculators — Concrete, Electrical, HVAC

210+ engineering calculators for structural, mechanical, electrical, HVAC, plumbing, and construction calculations.

Professional-Grade Calculators

Whether you're calculating concrete volumes, wire gauges, pipe flow rates, or solar panel arrays, ToolBox has over 210 engineering and construction calculators ready to use.

Structural Engineering

Moment of inertia, section modulus, shear stress, factor of safety, column load capacity, wind load, and snow load calculators.

Electrical

Ohm's law, LED resistor, 3-phase power, transformer turns, RC/RL time constants, resonant frequency, capacitor/inductor energy, wire resistance, power factor, and conduit fill calculators.

Construction

Concrete slab volume, drywall sheets, tile count, insulation R-value, lumber board feet, gravel, asphalt, rebar weight, wallpaper rolls, deck boards, and fence calculators.

HVAC & Plumbing

CFM calculator, heating load, water flow rate, water heater sizing, and pipe flow velocity.

Renewable Energy

Solar panel array sizing and battery bank calculators for off-grid and hybrid systems.