How to convert Ohms to Amps

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

It is possible to calculate amps from ohms and watts or volts, but you cannot 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 in ohms (Ω):

I(A) = V(V) / R(Ω)

So

Amps = Volts / Ohms

or

A = V / Ω

Example

Find the current of an electrical circuit that has a voltage supply of 12 volts and a resistance of 40 ohms.

The resistance R is equal to 12 volts divided by 0.3 amps:

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

Amps = √[Watts / Ohms]

or

A = √[W / Ω]

Example

Find the current of an electrical circuit that has a power consumption of 30W and a resistance of 120Ω.

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

I = √[30W / 120Ω] = 0.5A

Amps to Ohms ►

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