UOM Converter
Ohm's law
Enter any two of volts, amps, ohms and watts to get the other two.
Try an example
Convert from
120 V and 1,500 W gives
How it's calculated
- Volts = amps × ohms.
- Watts = volts × amps = amps² × ohms = volts² ÷ ohms.
For DC and resistive loads (heaters, incandescent). Motors and other inductive loads also need power factor.
Worked examples
120 V and 1,500 W gives
- Amps: 12.5 A
- Resistance: 9.6 Ω
12 V and 2 A gives
- Resistance: 6 Ω
- Power: 24 W
240 V and 20 Ω gives
- Amps: 12 A
- Power: 2,880 W
More in Electrical
kVA · kW · ampsTransformer, generator and UPS sizing. Three-phase uses line-to-line volts.- Voltage dropVoltage drop on a run, and the smallest wire that keeps it within your target.
- Power factor correctionCapacitor kvar needed to raise a load's power factor, and what it does to kVA and current.
- Transformer fault currentFull-load current and the maximum fault current at a transformer's secondary terminals, from kVA and nameplate impedance.
- Motor speed & slipSynchronous speed from frequency and poles, slip from the nameplate speed, and the same motor on the other frequency.
- Line ↔ neutral voltageThree-phase wye systems: line-to-neutral = line-to-line ÷ √3.
- Energy costWhat a load costs to run, and what a retrofit saves.