How does a 3-digit capacitor code work?

The first two digits are significant figures and the third is the number of zeros to append, giving a value in picofarads. So 104 means 10 followed by 4 zeros, equals 100000 pF, which is 100 nF or 0.1 µF.

What does the letter after the code mean?

The trailing letter is the tolerance. Common letters are J for plus or minus 5 percent, K for plus or minus 10 percent, and M for plus or minus 20 percent. Tighter grades like F (1 percent) appear on precision film capacitors.

What if the third digit is 8 or 9?

Digits 8 and 9 are special multipliers: 8 means multiply by 0.01 and 9 means multiply by 0.1. So a code ending in 9 gives a fraction of the two leading digits, used for very small capacitors.

How do I read a code without three digits?

A two-digit or plain number is the value directly in picofarads. For example, 47 means 47 pF and 22 means 22 pF. Only the 3-digit form uses the third digit as a zero-count multiplier.

Why convert between pF, nF, and µF?

Schematics and parts lists use different units by convention: small ceramics in pF, decoupling caps in nF, and bulk caps in µF. Showing all three lets you match the value to whatever the circuit diagram or BOM uses.

Capacitor Code Reference

Email me this result

Get this tool's output sent to your inbox, plus one useful tool a week. No spam, unsubscribe any time.

Small ceramic and film capacitors are too tiny to print a full value, so they use a compact 3-digit code. This reference decodes that code into picofarads, nanofarads, and microfarads, and handles the optional tolerance letter.

How it works

The 3-digit code works just like the resistor color code, but in picofarads:

value (pF) = (first two digits) × 10^(third digit)

So the code 104 is 10 × 10^4 = 100000 pF = 100 nF = 0.1 µF. Two special multiplier digits exist:

8 → × 0.01     9 → × 0.1

These give fractional results for sub-picofarad and small-value parts. A trailing letter encodes tolerance, e.g. J = ±5%, K = ±10%, M = ±20%.

Tips and example

223 decodes to 22 × 10^3 = 22000 pF = 22 nF — a common decoupling value.
A bare two-digit number is already in picofarads (47 = 47 pF).
Unit conversions: 1 nF = 1000 pF and 1 µF = 1000 nF.