How to Read Capacitor Markings: A Complete Guide

Decoding Capacitor Markings#

Reading capacitor markings can be confusing for beginners and even experienced technicians. Different manufacturers and capacitor types use different coding systems. This guide will help you decipher common capacitor markings.

1. The 3-Digit Code (Picofarads)#

Small capacitors (Ceramic, Film) often use a 3-digit code related to picofarads (pF).

First digit: 1st significant figure
Second digit: 2nd significant figure
Third digit: Number of zeros (multiplier)

Example: 104

1st digit: 1
2nd digit: 0
Multiplier: 4 zeros (0000)
Result: 100,000 pF = 100 nF = 0.1 µF (Common ceramic decoupling cap)

2. Tolerance Codes#

A single letter often follows the capacitance code to indicate tolerance.

J: ±5%
K: ±10%
M: ±20%

So "104K" means 0.1 µF ±10%.

3. Voltage Ratings#

Voltage is usually marked directly (e.g., "50V", "1kV"). Sometimes codes are used:

1H: 50V
2A: 100V
2E: 250V
2G: 400V
2J: 630V

4. Electrolytic Capacitors#

These large capacitors usually have values written directly (e.g., "470µF 25V"). Important: Look for the negative stripe! The stripe usually points to the negative lead (cathode). Connecting these backwards can cause failure.

Frequently Asked Questions#

What does "uF", "nF", and "pF" mean?#

These are units of capacitance:

µF (microfarad) = 0.000001 Farad
nF (nanofarad) = 0.000000001 Farad
pF (picofarad) = 0.000000000001 Farad Conversion: 1 µF = 1,000 nF = 1,000,000 pF.

Why do some capacitors have no polarity markings?#

Ceramic, film, and mica capacitors are non-polarized (bipolar). You can connect them in either direction. Only electrolytic and tantalum capacitors are typically polarized.

Decoding Capacitor Markings#

1. The 3-Digit Code (Picofarads)#

Small capacitors (Ceramic, Film) often use a 3-digit code related to picofarads (pF).

First digit: 1st significant figure
Second digit: 2nd significant figure
Third digit: Number of zeros (multiplier)

Example: 104

1st digit: 1
2nd digit: 0
Multiplier: 4 zeros (0000)
Result: 100,000 pF = 100 nF = 0.1 µF (Common ceramic decoupling cap)

2. Tolerance Codes#

A single letter often follows the capacitance code to indicate tolerance.

J: ±5%
K: ±10%
M: ±20%

So "104K" means 0.1 µF ±10%.

3. Voltage Ratings#

Voltage is usually marked directly (e.g., "50V", "1kV"). Sometimes codes are used:

1H: 50V
2A: 100V
2E: 250V
2G: 400V
2J: 630V

4. Electrolytic Capacitors#

Frequently Asked Questions#

What does "uF", "nF", and "pF" mean?#

These are units of capacitance:

µF (microfarad) = 0.000001 Farad
nF (nanofarad) = 0.000000001 Farad
pF (picofarad) = 0.000000000001 Farad Conversion: 1 µF = 1,000 nF = 1,000,000 pF.

Why do some capacitors have no polarity markings?#

Ceramic, film, and mica capacitors are non-polarized (bipolar). You can connect them in either direction. Only electrolytic and tantalum capacitors are typically polarized.

How to Read Capacitor Markings: A Complete Guide

Decoding Capacitor Markings#

1. The 3-Digit Code (Picofarads)#

2. Tolerance Codes#

3. Voltage Ratings#

4. Electrolytic Capacitors#

Frequently Asked Questions#

What does "uF", "nF", and "pF" mean?#

Why do some capacitors have no polarity markings?#

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Decoding Capacitor Markings#

1. The 3-Digit Code (Picofarads)#

2. Tolerance Codes#

3. Voltage Ratings#

4. Electrolytic Capacitors#

Frequently Asked Questions#

What does "uF", "nF", and "pF" mean?#

Why do some capacitors have no polarity markings?#