Enter any two of current, charge, and time to solve for the third.
How to Use the Current Calculator
Pick which of the three quantities to solve for — current, charge, or time — then fill in the other two. The hidden field is the one being calculated; everything updates as soon as both visible fields hold a number.
Current isn't defined by Ohm's Law — that relationship (V = IR) describes how current behaves in a resistive circuit, not what current actually is. The definition itself is simpler and older than any circuit theory: current is the rate electric charge moves past a point.
I = Q ÷ t
Q = I × t
t = Q ÷ I10 coulombs of charge passing a point over 5 seconds is a current of 2 amperes — which is also, not coincidentally, the literal definition of the ampere: one coulomb of charge per second. A car battery rated at 50 Ah is really just this same equation pre-multiplied out to a more convenient unit — 50 amp-hours means it can, in principle, deliver 50 amps for one hour, or 1 amp for 50 hours, before the charge runs out.
For the V/I/R relationship this calculator deliberately leaves out, see the Ohm's Law calculator — that's the right tool once resistance and voltage are the numbers in hand instead of charge and time.