﻿ RC Filter Calculator – Electric Druid

# RC Filter Calculator

### Resistor of 200.0 KΩ with capacitor of 470.0 pF

Capacitor (E, 10%)Resistor (E, 1%)Frequency ƒcToleranceTC 63%4TC 99%5TC 100%
470.0 pF200.0 KΩ1.7 kHz1.5 kHz – 1.9 kHz590.6 usec2.4 msec3.0 msec
470.0 pF220.0 KΩ1.5 kHz1.4 kHz – 1.7 kHz649.7 usec2.6 msec3.2 msec
680.0 pF200.0 KΩ1.2 kHz1.1 kHz – 1.3 kHz854.5 usec3.4 msec4.3 msec
680.0 pF220.0 KΩ1.1 kHz957.6 Hz – 1.2 kHz940.0 usec3.8 msec4.7 msec

Enter any two values to find the third one:

Note that you can enter values in typical formats. Case is ignored.

• For frequencies, '10k', '5KHZ','8MHz' and '1M' are all valid.
• For resistors, '100R', '470r', '1k2','47k', '2M2', and '10M' are all valid.
• For capacitors, '22p', '330p', '2n2', '10nF', '4.7u', '4u7', and '22uF' are all valid.

Since case is ignored, 'milli' prefixes will be interpreted as 'Mega'. This only really affects frequency.

A '1% resistor' usually means +/-1% tolerance. This calculator works this way. 10% is +/-10%.

Capacitors and Resistors are both limited to a 'typical' range; 10pF to <10000uF for caps, 1Ω to <100MΩ for resistors. Outside this range things will probably turn to nonsense.

## 4 thoughts on “RC Filter Calculator”

1. Rudy M says:

Very good tool,
Thanks!

2. Ernest Dines says:

The time constants don’t seem to be right. For 1M, 1nF, I’m getting 6.3ms. Should it not be 1ms?

1. Well spotted, Ernest. Thanks very much for that. It used to be ok, so it looks like it lost a “2 Pi” term in the transfer to the new website.
Now corrected.