# How to convert ohms to amps

How to convert resistance in ohms (Ω) to electric current in amps (A).

You can calculate amps from ohms and volts or watts, but you can't convert ohms to amps since amp and ohm units represent different quantities.

### Ohms to amps calculation with volts

The current *I* in amps (A) is equal to the voltage *V*
in volts (V), divided by the resistance *R* in ohms (Ω):

* I*_{(A)} = *V*_{(V)}* */*
R*_{(Ω)}

So

amp = volt / ohm

or

A = V / Ω

#### Example

What is the current of an electrical circuit that has voltage supply of 12 volts and resistance of 40 ohms?

The current I is equal to 12 volts divided by 40 ohms:

*I* = 12V / 40Ω = 0.3A

### Ohms to amps calculation with watts

The current *I* in amps (A) is equal to the square root of
the power *P* in watts (W), divided by the resistance *R*
in ohms (Ω):

_______________

* I*_{(A)} = *√P*_{(W)}* */*
R*_{(Ω)}

So

_______________

amp = *√ *watt / ohm

or

__________

A = *√ *W / Ω

#### Example

What is the current of an electrical circuit that has power consumption of 30W and resistance of 120Ω?

The current I is equal to the square root of 30 watts divided by 120 ohms:

________________

*I* = *√ *30W / 120Ω = 0.5A