This rc time constant reference table shows the time constant (τ) for a range of resistance values, assuming a capacitance of 1,000 µF. Every figure is computed with the same engine that powers our RC Time Constant Calculator, so the numbers are exact.
| Resistance | Time constant (τ) | Time to ~full charge (5τ) |
|---|---|---|
| 250 Ω | 0.2500 | 1.2500 |
| 500 Ω | 0.5000 | 2.5000 |
| 750 Ω | 0.7500 | 3.7500 |
| 1,000 Ω | 1.0000 | 5.0000 |
| 1,500 Ω | 1.5000 | 7.5000 |
| 2,000 Ω | 2.0000 | 10.0000 |
| 3,000 Ω | 3.0000 | 15.0000 |
| 5,000 Ω | 5.0000 | 25.0000 |
| 7,000 Ω | 7.0000 | 35.0000 |
| 10,000 Ω | 10.0000 | 50.0000 |
How to use this table
Find the row closest to your resistance and read across to the time constant (τ). For a value between two rows, the real figure sits between them — or enter your exact numbers in the RC Time Constant Calculator for a precise answer.
Need a value that is not in the table? — the RC Time Constant Calculator does it instantly, for free, with the formula and a worked example built in.
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