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.

What is the Capacitor Code Reference?

Decode the 3-digit codes printed on ceramic and film capacitors into picofarad, nanofarad, and microfarad values, including the optional tolerance letter. Enter a code like 104 and read 100 nF. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Capacitor Code Reference

Name: Capacitor Code Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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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%.

Common codes you will encounter

A handful of codes appear on the bench over and over. Here is a quick reference:

Code	Value in pF	Value in nF	Value in µF	Common use
101	100 pF	0.1 nF	—	RF bypass, small filter
103	10,000 pF	10 nF	0.01 µF	Audio coupling
104	100,000 pF	100 nF	0.1 µF	Decoupling (very common)
105	1,000,000 pF	1,000 nF	1 µF	Larger decoupling
223	22,000 pF	22 nF	0.022 µF	Decoupling, timing
472	4,700 pF	4.7 nF	—	Filter, snubber

The 104 (100 nF / 0.1 µF) is by far the most commonly placed capacitor in digital electronics — virtually every IC power pin gets one.

Tolerance letters explained

The letter after the code tells you how far the actual value can deviate from the marked value:

Letter	Tolerance	Typical use
F	±1%	Precision timing, oscillators
G	±2%	Precision filters
J	±5%	General signal work
K	±10%	Decoupling, power supply filtering
M	±20%	Bulk bypass, non-critical
Z	+80% / −20%	Economy electrolytic-style ceramics

For most decoupling applications a K (±10%) or M (±20%) part is perfectly adequate. Precision timing circuits, crystal oscillator load capacitors, and active filter designs benefit from F or G-grade parts.

Identifying unknown parts

When you pull a capacitor from a scrap board and need to identify it:

Check for a 3-digit code stamped on the body — that is the EIA capacitor code this tool decodes.
A two-digit number means the value is directly in picofarads (for example, 47 = 47 pF).
Some larger ceramic discs print the full value with a unit suffix (e.g., .1µ or 100n) — those do not need decoding.
If there is only a colour stripe, it may be an older disc ceramic using the old IEC colour code, which is a different system.

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.
When a schematic calls for 0.1 µF and you have a 104K in your parts bin, that is a match.