Why AmpToKW exists
AmpToKW started with a question heard on job sites, in classrooms and in garages: how much power is this current? A clamp meter shows amps, and breakers, cables and fuses are rated in amps. But electricity bills, generators, heaters, EV chargers and solar systems are sized in kilowatts. AmpToKW turns one into the other and shows the working, so every number on the screen can be checked by hand.
One calculator for each job
The site has 21 calculators. The main amps to kW calculator covers DC, single-phase and three-phase circuits with a live waveform, gauge and power triangle. Twenty more answer narrower questions: kWh used per hour, kW back to amps with a breaker size, battery power and runtime, generator loading and size, motor shaft power and horsepower, EV charging time, nameplate kW and kVA ratings, watts, and fixed-voltage pages for 220 V, 230 V, 240 V, 415 V, 440 V, 480 V, the UK, Australia and Bangladesh. Each one has its own chart, spreadsheet formula and worked examples.
Who uses it
Six groups use AmpToKW most. Electricians check whether a 32 A circuit can carry a 7 kW EV charger. Solar and off-grid installers convert 48 V battery current into kW and runtime. Facility managers size standby generators from measured amps. Maintenance technicians read a motor’s current and get shaft kW and horsepower. Students check three-phase homework one step at a time. Homeowners work out what a 13 A heater costs to run each hour.
How the numbers are checked
Every calculator uses the standard equations: P = V × I for DC, P = V × I × PF for single phase and P = √3 × V × I × PF for three phase, plus efficiency, runtime and charge-time formulas where a tool needs them. Each result shows its full formula, and the charts, spreadsheet examples and FAQ answers come from the same code as the calculators, so they always agree. AmpToKW is run by an independent developer with no ties to equipment makers or utilities, and the site carries no ads or paid placements. Results are estimates for planning and learning; a qualified electrician should check any installation.