Online calculator for calculating voltage, current, resistance and power
To calculate the voltage U , the current I , the resistance R or the power P two of the values must be known.

Ohm's law is a basis of electrical engineering and electronics. It indicates the relationship between voltage, current and electrical resistance. The law says that the voltage is equal to the current multiplied by the resistance.
Voltage 
\(\displaystyle U=R · I\) 
\(\displaystyle U=\sqrt{P · R}\) 
\(\displaystyle U=\frac{P}{I}\) 
Current 
\(\displaystyle I=\sqrt{\frac{P}{R}}\) 
\(\displaystyle I=\frac{U}{R}\) 
\(\displaystyle I=\frac{P}{U}\) 
Resistance 
\(\displaystyle R=\frac{P}{I^2}\) 
\(\displaystyle R=\frac{U^2}{P}\) 
\(\displaystyle R=\frac{U}{I}\) 
Power 
\(\displaystyle P=U · I\) 
\(\displaystyle P=I^2·R\) 
\(\displaystyle P=\frac{U^2}{R}\) 
