# µ in the Middle of a Capacitor Rating

I'm looking at an electrolytic capacitor (and old blue, Philips one used in electronics classes) and am wondering why it is printed with 4µ7-M.

I tried Googling, figuring that it was a common enough occurrence, but found nothing.

Is that supposed to be a 47µF cap? Why is the µ in the middle of the number? What is the -M for?

Thanks.

• Thanks guys. I'm not sure I have seen this before (although the answers do seem vaguely familiar). The explanations for it also make sense. Thanks again. Commented Dec 8, 2010 at 6:08

The "µ" symbol is put in place of the decimal point, 4µ7 translates to 4.7 µ farads.

Not too sure about the "-M" part tho - sorry

• This is correct. You will also see this on some resistors were it will say 4k2 and mean 4.2k ohm. Commented Dec 6, 2010 at 16:14
• I suspect the M is probably some kind of indication of the dielectric temperature characteristic or voltage rating. It's probably a manufacturer specific code. Commented Dec 6, 2010 at 16:25
• The "M" stands for tolerance code. J = +/-5% K = +/-10% M = +/-20% Commented Dec 23, 2020 at 11:06

Like Jim said, the µ indicates the place of the decimal point. This isn't restricted to capacitors, but also used for resistors and inductors:

resistor 31k6 = 31.6 kiloOhm
resistor 5M6 = 5.6 megaOhm