Ohms Law Calculator
Please provide any 2 values and click "Calculate" to get the other values in the ohm's law equations V = I × R and P = V × I.
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Ohm's Law
Ohm's Law describes that the electric current flowing through a conductor connecting two points varies in direct proportion to the applied voltage. This relationship holds for a broad spectrum of materials and across wide voltage and current ranges, keeping the resistance and conductance of components made from these substances essentially unchanged. The law applies to circuits composed solely of resistive parts—no capacitors or inductors—and remains valid whether the source voltage or current is steady (DC) or alternating (AC). It can be represented by several equations, typically presented together as shown below.
| V = I × R | ||||
| R = |
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| I = |
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Where:
R is resistance in Ohms
I is current in Amperes
Electrical Power
Power quantifies how quickly electrical energy is moved through a circuit, measured per unit of time, commonly expressed in watts, the SI unit. Electrical power is usually generated by power plants and delivered to industries and households via the electric grid, though batteries and other sources can also provide it.
In resistive circuits, Joule's Law can be combined with Ohm's Law to produce alternative expressions for the amount of power dissipated, as shown below.
| P = V × I | ||||
| P = |
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| P = I2 × R | ||||
Where:
Ohm's Law Formula Wheel
The diagram below illustrates a formula wheel that connects the Ohm's Law variables P, I, V, and R. It mirrors the calculator's functionality by visualising the algebraic rearrangements of the earlier equations. To employ the wheel, pick the desired unknown variable at the centre and then apply the relationship linking the two known quantities located in the surrounding segments.
