Calculators and charts for home wiring and landscape materials
13 calculators and 13 printable charts for home wiring and landscape materials: wire size and voltage drop, breaker and ground wire sizes, appliance power use, and cubic yards, tons and bags of gravel, soil and mulch for 11 materials. Every result shows how it was calculated and the sources behind the numbers.
Electrical calculators
- Box fill calculatorCount the wires, devices, clamps and grounds in an electrical box and find the cubic inches it needs and the smallest standard box that fits.
- Conduit fill calculatorCheck how full a conduit is with any mix of THHN wires, or find the smallest EMT, PVC or rigid conduit that holds them.
- Electricity cost calculatorWork out how many kWh an appliance uses and what it costs to run per day, month and year from its watts, hours of use and your rate.
- kVA to amps calculatorConvert transformer or generator kVA to amps at 120/240 V single phase and 208, 240 or 480 V three phase, and amps back to kVA.
- Electrical load calculatorEstimate a house's electrical load from its floor area, appliances, heating and air conditioning, and the service size it needs in amps.
- Ohm's law calculatorEnter any two of volts, amps, ohms and watts to get the other two, with the formula and every step of the calculation.
- Watts to amps calculatorConvert watts to amps and amps to watts at 120, 240 or any voltage, single or three phase, with power factor for motors.
- Wire size calculatorFind the wire gauge for a circuit by amps, distance and voltage. Shows the voltage drop, the size required by ampacity and when a long run needs a larger wire.
Electrical charts
- Ampacity chartAllowable amps for copper and aluminum conductors from 14 AWG to 600 kcmil at 60, 75 and 90 °C, with the small-conductor breaker limits.
- Appliance wattage chartRunning watts and amps of common household appliances at 120 and 240 V, with the breaker and circuit each one needs.
- AWG chartAmerican Wire Gauge sizes from 18 AWG to 600 kcmil: diameter in inches and millimeters, area in circular mils and mm², resistance per 1,000 ft.
- Breaker size chartLargest breaker for each wire size from 14 AWG to 600 kcmil, copper and aluminum, for NM-B cable and for 75 °C terminations.
- Conduit fill chartMaximum number of THHN wires from 14 AWG to 4/0 in EMT, PVC Schedule 40 and 80 and rigid conduit from 1/2 to 4 inches.
- Ground wire size chartMinimum equipment grounding conductor for every breaker from 15 to 1,200 amps, copper and aluminum, and how to size it on long runs.
- Extension cord gauge chartWhich extension cord gauge to use for a load from 5 to 15 amps at 25, 50, 100 and 150 feet, keeping the voltage drop within 5%.
- Generator wattage chartRunning and starting watts of household appliances and the generator size each one needs, from a refrigerator to central air.
- Motor FLA chartFull-load amps of single-phase and three-phase AC motors by horsepower and voltage, with the 125% conductor ampacity for the branch circuit.
- Voltage drop chartHow far each copper wire size can run at full load before the voltage drop passes 3%, at 120 and 240 volts.
- Wire gauge chartAWG wire sizes from 18 to 4/0 with diameter, cross-section, amps for copper NM-B cable and THHN, the largest breaker and what each size is used for.
- Wire size chartWire size for every standard breaker from 15 to 400 amps in copper and aluminum, for NM-B cable and for 75 °C terminations.
Materials calculators
- Cubic yard calculatorA 10 by 10 ft area 3 inches deep is 0.93 cubic yards (25 cubic feet). Cubic yards for a rectangle, circle or triangle, with tons for a chosen material.
- Gravel driveway calculatorA 20 by 10 ft gravel driveway with 4 in over 12 in of compacted gravel takes about 15.8 tons (layers from Maine DEP's gravel road manual).
- Paver sand calculatorA 20 by 10 ft paver patio with 1 in of sand over 6 in of compacted crusher run takes about 7.84 tons. Layer thicknesses from a paver manufacturer guide.
- Square feet to cubic yards100 sq ft at 3 inches deep is 0.93 cubic yards; one cubic yard covers 108 sq ft at that depth. Coverage at 1 to 12 inches.
- Tons to cubic yardsOne ton of gravel at 2,565 lb per loose cubic yard is 0.78 cubic yards. Tons to cubic yards and back by the published weight of each landscape material.