Electrical & Plumbing Calculatrices

Calculate correct wire gauge from load and run length per NEC 2023 ampacity tables. Enter amps, length, and conduit type — see minimum AWG with voltage drop. Free.

Calculate circuit breaker size per NEC 210.20. Enter connected load in amps — see breaker size with 125% continuous load rule and next standard size. Free.

Calculate total electrical load for residential or commercial panel. Enter appliances and demand factors — see total load, service size, and NEC compliance. Free.

Calculate conduit fill percentage per NEC Chapter 9 Table 1. Enter wire sizes and conduit type — see fill % (40% max for 3+ wires) and minimum conduit size. Free.

Calculate voltage drop over a wire run. Enter current, wire length, AWG, and material — see % drop (NEC max 3% branch, 5% total) with corrective options. Free.

Calculate panel load schedule and available capacity. Enter breaker sizes and connected loads — see total demand, panel utilization, and spare capacity. Free.

Calculate generator kW requirements for standby or prime power. Enter critical loads and starting kVA — see required generator size with safety margin. Free.

Calculate solar array size to offset electricity consumption. Enter daily kWh usage, location, and panel wattage — see panels needed, roof area, and payback. Free.

Calculate battery bank capacity for solar or backup power. Enter load, autonomy days, and depth of discharge — see Ah required, battery count, and bank size. Free.

Calculate transformer kVA rating from load. Enter load in kW and power factor — see required kVA with standard size selection and NEC derating. Free.

Calculate motor starter and overload relay sizing. Enter motor HP, voltage, and FLA — see starter size, overload setting, and NEC 430 compliance. Free.

Calculate power factor and capacitor bank needed for correction. Enter kW and kVAR — see PF, kVAR correction required, and utility penalty threshold. Free.

Calculate total harmonic distortion (THD) impact on electrical systems. Enter fundamental and harmonic components — see THD % with IEEE 519 compliance. Free.

Calculate pipe flow rate using Hazen-Williams or Darcy-Weisbach equation. Enter pipe diameter, pressure, and length — see flow rate, velocity, and friction loss. Free.

Calculate minimum pipe diameter for a required flow rate. Enter flow rate, fluid, and maximum velocity — see pipe size with pressure drop per foot. Free.

Calculate pressure drop in pipe runs. Enter flow rate, pipe length, diameter, and fittings — see total pressure loss with equivalent length method. Free.

Calculate water hammer pressure surge in piping systems. Enter flow velocity and valve closing time — see surge pressure with mitigation recommendations. Free.

Calculate drain pipe slope for gravity drainage per IPC. Enter pipe length and diameter — see required slope in inches/foot with 1/4 inch per foot standard. Free.

Calculate septic tank and drain field size. Enter daily wastewater flow and soil percolation rate — see tank size and leach field area per state guidelines. Free.

Calculate water heater size from household demand. Enter occupants, peak hour demand, and recovery rate — see tank size or tankless flow rate. Free.

Calculate boiler output (BTU/hr) for space heating. Enter building heat loss and distribution type — see required boiler output with safety factor. Free.

Calculate pump horsepower and impeller size. Enter flow rate, total head, and fluid — see required pump HP with NPSH check and efficiency curve. Free.

Calculate grease interceptor size per PDI G-101. Enter fixtures and peak flow — see interceptor capacity in gallons with local code reference. Free.

Calculate drainage fixture units and required drain stack size per IPC. Enter fixture types and counts — see total DFU and minimum pipe diameter. Free.

Calculate HVAC BTU/hr requirement using Manual J methodology. Enter room dimensions, insulation, climate zone, and windows — see required capacity. Free.

Calculate HVAC duct size using equal friction method. Enter CFM and max friction rate — see duct dimensions for round, rectangular, and flex duct. Free.

Calculate air volume (CFM) for ventilation per ASHRAE 62.1. Enter room size and occupancy type — see required CFM with ACH and exhaust fan sizing. Free.

Calculate total external static pressure in HVAC duct system. Enter duct segments, fittings, and coil drops — see TESP vs blower performance curve. Free.

Calculate correct refrigerant charge for HVAC systems. Enter system size, line set length, and temperature — see charge weight with superheat/subcooling targets. Free.

Calculate building heat load (heating) from envelope losses. Enter U-values, areas, and design temperatures — see total BTU/hr with heat loss breakdown. Free.

Calculate building cooling load from sensible and latent heat gains. Enter occupants, equipment, solar, and envelope — see total tons of cooling needed. Free.

Calculate required ventilation rate per ASHRAE 62.1-2022. Enter occupancy type and floor area — see minimum CFM with CO2 level verification. Free.

Calculate relative humidity, specific humidity, and dew point from temperature and wet bulb readings. Enter psychrometric inputs — see all humidity metrics. Free.

Calculate dew point temperature from air temperature and relative humidity. Enter temp and RH — see dew point with condensation risk and HVAC implications. Free.

Calculate EER and SEER for HVAC equipment. Enter BTU output and watt input — see EER/SEER with DOE minimum and ENERGY STAR thresholds. Free.