What this calculator does
RC circuit charge & discharge works out how a capacitor charges or discharges through a resistor over time. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulaτ = RC; Vcharge(t) = V₀(1−e^(−t/τ)); Vdischarge(t) = V₀e^(−t/τ)
The inputs explained
| Field | What to enter |
|---|---|
| Resistance (Ω) | A number, measured in Ω. Starts at 1000. |
| Capacitance (µF) | A number, measured in µF. Starts at 1000. |
| Supply voltage (V) | A number, measured in V. Starts at 9. |
| Elapsed time (s) | A number, measured in s. Starts at 1. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with resistance
Every other input is held at the calculator’s starting values while resistance varies. Select any row to load that scenario into the calculator.