Electronic Components
Capacitor Charging Calculator
Capacitor Charging helps you find capacitor voltage from supply voltage, resistance, capacitance, and elapsed time. The page keeps the arithmetic visible so you can check the result against the original measurements.
Set up the Capacitor Charging case
Use measurements from one operating condition.
Capacitor voltage: calculation method
Start with the equation Vc = Vs(1 − e^(−t/RC)). The formula draws on Supply voltage, Resistance, Capacitance, and Elapsed time.
The defaults produce 7.585 V. Replace them with measurements from one operating state.
Calculate capacitor voltage during RC charging. For the companion remaining voltage calculation, open Capacitor Discharging Calculator.
Preparing the calculation
Record tolerance, bias point, duty cycle, and junction temperature. If operating conditions changed between readings, calculate separate cases.
A denominator entry cannot be zero. Confirm decimal placement whenever a source uses a different unit scale.
- Supply voltage
- Default example: 12 V. Enter supply voltage in V.
- Resistance
- Default example: 10000 Ω. Enter resistance in Ω.
- Capacitance
- Default example: 100 µF. Enter capacitance in µF.
- Elapsed time
- Default example: 1 s. Enter elapsed time in s.
Checks that catch bad inputs
Mixing nominal and measured data is a common source of error.
Check the input source before adding a safety or correction factor.
Checks before using the answer
The model assumes an initially discharged capacitor and a constant DC source.
The arithmetic intentionally leaves out parasitics, layout inductance, tolerance stack-up, switching edges, and thermal resistance. Test an additional scenario when an omitted effect has a plausible range.
Keep nominal component markings separate from measured operating values.
Sensitivity check
Change Supply voltage from 12 V to 14.399999999999999 V while preserving the other measurements. The output changes from 7.585 V to 9.103 V.
Keep both cases when the changed input represents genuine uncertainty.
Common questions before using the result
Does Capacitor Charging Calculator choose a final rating?
The calculator does not approve equipment or supply an unexplained margin. Compare against the selected component data-sheet limits.
What precision should move to the next worksheet?
Do not round between dependent calculations. Match the final display to the precision of the source data.
Which input can create an undefined result?
A zero denominator is undefined, so the affected field has a positive minimum.
What data should go into Capacitor Charging?
Use supply voltage, resistance, capacitance, and elapsed time from one operating condition. Use data-sheet values at the intended voltage, current, frequency, and temperature.
What should I verify beyond the displayed inputs?
The model assumes an initially discharged capacitor and a constant DC source. Also consider bias dependence, ESR, leakage, saturation, and self-heating.
Why might a second instrument give another answer?
Recheck units and operating state before investigating parasitics, layout inductance, tolerance stack-up, switching edges, and thermal resistance.