Wattage to Amperage Calculator
Omni's wattage to amperage calculator allows you to calculate the current through an AC or DC circuit from power and voltage values.
If you have ever wondered how to convert watts to amps, i.e., power to current for a given circuit, you have come to the right place.
Continue reading to learn how to calculate amperage from wattage and voltage for various circuit types. You will also find an example of using this wattage voltage amperage calculator.
Before going any further, let us understand what exactly we mean by the terms wattage, voltage, and amperage.
Wattage, voltage, and amperage
There is production or dissipation of power by the circuit elements (e.g., resistors) in every electrical circuit. We can express the power dissipation by the equation:
where:
 $P$  Power or wattage dissipated by the circuit element expressed in watts (W);
 $I$  Current or amperage through the circuit element measured in units called amperes (A); and
 $V$  Voltage across the element expressed in the unit volts (V).
Thus, when we talk about calculating amperage from wattage or converting wattage to amperage, we simply mean using the above equation to calculate the current from power and voltage values.
How to calculate amperage from wattage
To calculate the current or voltage from power, we first need to know the circuit type, i.e., AC or DC. Then we can use one of the formulae given below to convert watts to amps:
For DC circuit, the relation between power ($P$), voltage ($V$) and current ($I$) is given as:
For the singlephase AC circuit, we can use the following formula to convert watts to amps:
Where:
 $I_{RMS}$  Root mean square current;
 $P_{avg}$  Average power;
 $V_{RMS}$  Root mean square voltage; and
 $PF$  Power factor, which is the ratio between the real and apparent power in a circuit.
Not sure how to calculate power factor? Worry not! We have a tool for that too.
If the circuit is a threephase AC circuit, we can use the formulae:
How to use the wattage to amperage calculator?
Let us calculate the amperage of an electrical appliance using 1500 watts of power and running on a 120 V DC circuit:

Using the dropdown menu, choose the current type as DC.

Enter the power as 1500 W and voltage as 120 V.

The calculator will convert 1500 watts to amps for the given condition and show the resulting current as 12.5 A.
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FAQ
How does wattage relates to amperage for AC singlephase circuit?
For an AC singlephase circuit, the relation between power in wattage (P
) and current in amperage (I
) is given by the formula:
I = P / (V × PF )
. Here PF
is the power factor, and V
is the RMS (root mean square) voltage in volts.
How do I calculate amperage from wattage and voltage for DC circuit?
To calculate amperage from wattage and voltage for the DC circuit, follow the given instructions:

Divide the power in wattage (W) by the voltage in volts (V).

Congrats! You have calculated the amperage from wattage and voltage.