Enter any two of voltage, energy, and charge to solve for the third.
How to Use the Voltage Calculator
Choose voltage, energy, or charge as the value to solve for, enter the other two, and the answer appears in the highlighted card the moment both remaining fields are filled in.
Ohm's Law (V = IR) is how most people first meet voltage, but it describes voltage's relationship to a resistive circuit, not what voltage fundamentally measures. The more basic definition: voltage is energy delivered per unit of charge moved.
V = W ÷ Q
W = V × Q
Q = W ÷ V10 joules of energy moving 2 coulombs of charge is a potential difference of 5 volts — and that's the actual definition of the volt, not an approximation of one: one volt equals one joule per coulomb. A 12 V car battery, read this way, delivers 12 joules of energy for every coulomb of charge it pushes through a circuit, regardless of what resistance sits on the other end.
Looking for voltage as it relates to current and resistance instead? That's the Ohm's Law calculator's job, not this one's — this page only ever touches energy and charge.