RC Time Constant Calculator

Explore capacitor charging speed and RC low-pass cutoff from resistance and capacitance.

Time constant (τ)
10.00 ms
Time to 63.2% 10.000 ms
Time to 90% 23.026 ms
Corner frequency 15.92 Hz
Inputs
Ω
Series resistance in the ideal RC path.
F
Capacitance in farads.
V
Final ideal capacitor voltage.
Results & Graph
Time constant (τ)
10.00 ms
Time to 63.2%
10.000 ms
Time to 90%
23.026 ms
Corner frequency
15.92 Hz

RC charging curve and cutoff frequency

Graph 1 • Entered design case Domain-specific illustration generated from the active calculator inputs.
R=10.0k ΩC=0.0 F • τ=10 ms
Graph 2 • Engineering outputs Time to approach the final voltage.
τ (63.2%) 0.01 s 90% charge 0.023 s 99% charge 0.046 s
Graph 3 • Calculated response Ideal first-order charging toward 5 V.
0V 2.7V 5.4V 0τ: 0 V 0 0τ 0.5τ: 1.967 V 1τ: 3.161 V 3.2 1τ 1.5τ: 3.884 V 2τ: 4.323 V 4.3 2τ 2.5τ: 4.59 V 3τ: 4.751 V 4.8 3τ 3.5τ: 4.849 V 4τ: 4.908 V 4.9 4τ 4.5τ: 4.944 V 5τ: 4.966 V 5.0 5τ
Summary: The capacitor reaches 63.2% of its final voltage after one time constant (0.01 s).
Summary: For R=10000 Ω and C=0.000001 F, τ=RC=0.01 seconds and the ideal first-order corner frequency is 15.92 Hz.
⚠️ Ideal first-order RC circuit. Source resistance, component tolerances, leakage, and loading are excluded.

Formula & Mathematical Methodology: RC Time Constant Calculator

τ=RC
Vc(t)=Vs(1−e−t/RC)
fc=1/(2πRC)
τ=RC; Vc(t)=Vs(1−e^(−t/RC)); fc=1/(2πRC)
  • : Series resistance
  • : Capacitance
  • : Time constant
  • : First-order corner frequency

Rounding: Displayed values are rounded for readability; calculations retain full floating-point precision.

Worked Example: 10 kΩ resistor and 1 µF capacitor

Estimate charge timing with a 5 V ideal source.

  1. Multiply resistance by capacitance to find τ.
  2. Compute 63.2% and 90% charge timing.
  3. Calculate the corresponding first-order corner frequency.
Result: The time constant is 10 ms and corner frequency is about 15.9 Hz.

Frequently Asked Questions

What does one time constant mean?

For an ideal charge step, the capacitor reaches about 63.2% of its final voltage after one time constant.

Science & Engineering • Electronics Guide

How to Use the RC Time Constant Calculator: Practical Guide & Visual Analysis

Enter resistance, capacitance and source voltage to calculate an ideal RC charging curve. Whether you are researching rc time constant calculator, capacitor charging calculator, rc cutoff frequency, resistor capacitor time calculator, this interactive tool helps you calculate the time constant, 63.2% and 90% charge times, and corner frequency for an ideal first-order RC circuit.

Interpreting the 3 Custom Visual Graphs & Key Outputs

As you adjust Resistance, Capacitance, Supply Voltage, the calculator immediately computes Primary result, Supporting calculation metrics, Three calculator-specific visualizations and updates all three domain-specific SVG charts in real time. Instead of relying on a single static figure, you can inspect the primary domain diagram, component breakdown, and multi-point trajectory curve to see how changing your inputs shifts the final result. Use the Compare (up to 3 scenarios) button to evaluate side-by-side variations before making a decision.

Real-World Benchmark & Planning Tips (Global; user-entered values, assumptions and currency)

In our benchmark scenario (10 kΩ resistor and 1 µF capacitor), The time constant is 10 ms and corner frequency is about 15.9 Hz. Keep in mind that ideal voltage step, resistor and capacitor, with no source or load impedance. For related calculations in Science & Engineering, explore Ohm's Law, Wire Voltage Drop & Resistor Series/Parallel Calculator, Geometry Calculator (Right Triangle, Circle & Cylinder), Unit Conversion Calculator.