A quick and easy calculator for all your nF / uF / pF conversions
uF / nF / pF Calculator
Guide to cap numbers…
Seen those numbers on the caps and wondered what the hell they are? me too! However.. there’s an easy way to work it out.
Caps have numbers on them, like 102,103,224…the last of the numbers tells you how many zero’s to add to the number – which will give you the picofarad value (pF).
- 102 = 10 + 2 zeros = 1000pF … ( pF / 1000 = nF) … ( 1000 / 1000 = 1nF)
- 103 = 10 + 3 zeros = 10000pF … ( pF / 10000 = nF) … ( 10000 / 1000 = 10nF)
- 224 = 22 + 4 zeros = 220000pF … ( pF / 1000 = nF) … ( 220000 / 1000 = 220nF)
Caps with a decimal place
A cap that has a decimal place / period / full stop (call it what you will) is usually measured in uF.
- .47 = .47uF … (uF * 1000 = nF) … ( .47 * 1000 = 470nF)
- .63 = .63uF … (uF * 1000 = nF) … ( .63 * 1000 = 630nF)
Letters are tolerance
The letter that appears on a cap indicates the tolerance of the value:
J = +/- 5%
K = +/- 10%
M = +/- 20%
- .33J indicates .33 uF +/- 5% of .33 uF.
- .47K indicates .47 uF +/- 10% of .47 uF.
The maximum voltage is the last value to be displayed on a cap – take not that all pedal related caps should be at least 16v or higher – whilst most builds are only 9v, some bigger builds may run at 18v or have a charge pump inside that increases the voltage. So make sure the caps you use are above the maximum voltage of your circuit..or they will pop!
Note that the larger the operating voltage of the cap, “usually” this indicates the cap will be a bigger size (not always!) so make sure you check the size and pitch (the pitch is the distance between the legs) when you place your order.
- A cap marked 25V will operate up to 25V, but if the voltage surpasses this, it’s prone to failure.
You may see other random markings on your cap – like “WIMA – AAA” – these are manufacturer specific and don’t usually have any bearing on the cap itself.