Electrical, Heating & Insulation calculators
Amps, wire size, conduit fill, generator, heat loss, R-value, AC, water heater, ceiling fan, recessed lighting and solar angle calculators for the home.
- Amp CalculatorConvert watts, kilowatts, horsepower or kVA to amps for DC, single-phase and three-phase circuits, with power factor and motor efficiency taken into account.
- BTU Calculator for Room Air ConditionersEstimate the BTU per hour a window or portable air conditioner needs for a room, using its floor area, sun, occupants and kitchen use.
- Ceiling Fan Size CalculatorFind the right ceiling fan size for your room from ENERGY STAR's sizing table, and how high to hang it for your ceiling, from flush mounts to tall ceilings.
- CFM CalculatorSize a bathroom fan, a range hood or the airflow for any room in cubic feet per minute, using the Home Ventilating Institute's rules and the code minimums.
- Conduit Fill CalculatorCheck conduit fill for THHN wire in EMT, PVC, rigid or flexible conduit: the percent fill, the most wires that fit and the smallest trade size that works.
- Electricity Cost CalculatorWork out the kWh a device uses and what it costs per day, month and year from its watts, hours of use, days per week and your price per kWh.
- Generator Size CalculatorFind the generator size you need from the appliances you want to run: running watts, the starting surge of the biggest motor, and a margin on top.
- Heat Loss CalculatorEstimate your home's heat loss in BTU per hour through the walls, windows, ceiling, floor and air leaks, at your design temperature, to size heating.
- Insulation CalculatorFind the R-value ENERGY STAR recommends for your attic or floor and climate zone, the depth that gives it, and the bags of blown-in insulation to buy.
- R-Value CalculatorAdd up the R-value of a framed wall layer by layer, and see the whole-wall R-value once the studs are counted, with batts, blown-in, spray foam and rigid foam.
- Recessed Lighting CalculatorPlan recessed lights for a room: how many, how far apart and how far from the walls, with a check that they give enough light for the room.
- Solar Panel Angle CalculatorFind the best tilt for your solar panels from your latitude: year-round, summer and winter, month by month, and as a roof pitch, plus which way to face them.
- Voltage Drop CalculatorWork out the voltage drop on copper or aluminum wire for DC, single-phase and three-phase circuits, and find the smallest AWG size for your run.
- Water Heater Size CalculatorSize a water heater the Department of Energy way: a tank by its first-hour rating from your busiest hour, a tankless heater by flow and temperature rise.
- Wire Size CalculatorFind the wire gauge for a circuit from its current, voltage and run length, with ampacity and voltage drop checked together, for copper and aluminum.