# Capacitor Energy and Time Constant Calculator

This calculator computes the energy in a capacitor, given the voltage across it.

If you specify a load resistor it will also compute the time constant, or the time until the voltage drops to 37%, or charges to 63%.

See our standard resistor calculator for a real world resistor value.

**Equations:**

E= V^2*C/2

TC= R*C

1/e = 36.8%