Enter current in amps and voltage to get power in watts — the reverse of watts to amps.
Multiply by hours used to estimate daily kWh consumption for any device or circuit.
Once you know a circuit's current draw — from a breaker rating, a nameplate, or a clamp meter reading — this converts it to power so you can compare it against a panel's output or an inverter's rated capacity.
This conversion comes up constantly when sizing solar or battery equipment against appliance nameplates — a generator's continuous output is usually stamped in watts, but the circuit breaker protecting it is rated in amps, so you're translating between the two labels every time you check whether a load fits within a circuit's limit.
Breakers, fuses, and wire ratings are almost always specified in amps, while solar panels and generators are rated in watts — this bridges the two when you're reading electrical labels.
Both — use the total amperage of a subpanel or the amperage of a single appliance nameplate; the math is the same either way.
Use the Ohm's Law calculator first to solve for amps from volts and resistance, then bring that amp figure back here — the two tools are meant to be used together for a full picture.