Amps to Ohms Calculator
Convert amps to ohms from the circuit voltage: R = V / I. Formula, worked example and a table of typical values. Amps alone cannot give ohms.
Try your own numbers
Estimate only. Not engineering or safety advice. Check the result against the applicable standard and the equipment data, and have a competent engineer review it before it is relied on. Terms of use.
Open in the calculator with these values
Formula
Worked example
| Input | Value |
|---|---|
| Voltage | 12 V |
| Current | 2 A |
- R = V / I = 12 / 2 = 6 Ω
- P = V × I = 24 W
Typical values
| Current (A) | Resistance (Ω) |
|---|---|
| 0.5 | 24 |
| 1 | 12 |
| 2 | 6 |
| 5 | 2.4 |
| 10 | 1.2 |
| 20 | 0.6 |
Other inputs are the same as in the worked example above.
Assumptions
- Steady DC or purely resistive AC load
- AC values are RMS
- Power factor is 1; for a reactive load use the power, voltage and current calculator
Exactly two values are needed. If three or four are entered the result could contradict itself, so the calculator asks for two only.
Frequently asked questions
How do I convert Amps to Ohms?
V = I × R; P = V × I; P = I² × R; P = V² / R. Worked example: Voltage 12 V, current 2 A gives 6 Ω.
What do I need to enter?
Enter voltage, current, resistance and power. Leave blank the value you want to find, and the form solves for it. Change the unit of a value with its selector and the result stays the same.
Why does this need a second value?
Amps, volts and ohms are three different quantities linked by Ohm's law, V = I × R. Any one of them can be found only from the other two, so a single number cannot be converted on its own.
Does this work for AC circuits?
Only for resistive loads using RMS values. For a coil, motor or capacitor the opposition to current is impedance, which depends on frequency and phase; use the AC Ohm's law (phasors) calculator in Elecmetric.
How accurate are the results?
Every figure comes from the same tested engine as the Elecmetric calculators and is meant for estimating. Check design values against the standard and the equipment data you work to.
Related
Next steps in a design: Ohm's LawVolts to WattsAmps to VoltsAC Ohm's Law
Opposite direction: Ohms to Amps
Also see: Volts to Ohms Ohms to Volts Amps to kW kW to Amps
Formula guides: Ohm’s Law Formulas and Power WheelResistor Formulas: Series, Parallel, Divider
All 78 conversionsWatts, Volts, Amps, Ohms (any two) in Elecmetric