Capacitor Code Calculator decodes 3-digit capacitor codes (e.g., 104, 223), letter tolerance, voltage rating, and EIA marking with formulas, examples, FAQs, and references.

Capacitor Code Calculator - pF, nF, uF and Tolerance

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

Small capacitors rarely have room for a friendly label. A code like 104 means 10 followed by 4 zeros in pF, so 100,000 pF, or 100 nF, or 0.1 uF. Once you know the trick, the drawer full of tiny parts gets less annoying.

Formula at a glance

  • 3-digit code: first two digits are value, third digit is zeros in pF
  • 104 = 10 x 10^4 pF = 100 nF = 0.1 uF
  • uF = pF / 1,000,000

Field note: Old capacitors can drift, leak or fail short. Decode the marking, then measure if the circuit is fussy.

μF

Calculator Tool

Enter values to compute

V
Results
Click Calculate

Formulas

3-DigitpF = (Digit1_2) * 10^(Digit3)
Conversion1 µF = 1000 nF = 10^6 pF
ReactanceXc = 1 / (2πfC)

Quick Reference: Common Codes

CodepFnFµF
1011000.10.0001
102100010.001
10310,000100.01
104100,0001000.1
1051,000,00010001.0
10610,000,0001000010.0

Related Calculators

RC Filter Ohm's Law Voltage Divider

How to use the Capacitor Code Calculator

Use this as a bench check, then compare it with the part marking, tolerance and a meter reading when the circuit matters. Small components are cheap. Bad assumptions are not.

Worked example

Example: code 473 is 47 x 10^3 pF = 47,000 pF = 47 nF = 0.047 uF. Code 225 is 2,200,000 pF = 2.2 uF.

Practical checks before you trust the number

  • Check voltage rating separately. The value code is not the whole part number.
  • Tolerance letters matter in filters and timing circuits.
  • Electrolytic capacitors are polarized. Put one in backward and it may vent.

Common mistake

Old capacitors can drift, leak or fail short. Decode the marking, then measure if the circuit is fussy.

Sources and references

Related calculators

Frequently Asked Questions

The 104 code is a three-digit shorthand. The first two digits are the value in picofarads, and the third is the number of zeros to add. So 104 means 10 followed by 4 zeros = 100,000 pF = 100 nF = 0.1 µF. This is the most common decoupling capacitor you see across MCU boards and small LED driver PCBs. Memorize 104 = 0.1 µF and 105 = 1 µF and you'll save serious time at the bench.

103 follows the same three-digit rule: 10 followed by 3 zeros = 10,000 pF. Convert to microfarads by dividing by 1,000,000, which gives 0.01 µF. In nF that's 10 nF. We see this value in noise filters, RC snubbers across relay contacts, and audio coupling. If you ever feel unsure, pull out a capacitance meter and verify — small ceramics are notorious for fading markings and mixed-up bins.

Picofarad to nanofarad: divide by 1,000. Nanofarad to microfarad: divide by 1,000 again. So 1,000 pF = 1 nF = 0.001 µF and 1,000,000 pF = 1,000 nF = 1 µF. Walking up: 47 pF stays 47 pF. 4,700 pF becomes 4.7 nF. 4,700,000 pF becomes 4.7 µF. I keep the conversion ladder taped near my workbench because this trip-up breaks more student projects than any other single error.

Those letters are tolerance codes, just like the colored bands on resistors. J = ±5%, K = ±10%, M = ±20%. You'll also see F = ±1% and G = ±2% on precision parts. So a capacitor marked 104K is 100 nF ±10%. For timing circuits like 555 oscillators or filters, never use M-class — the frequency drift will throw your design off. Stick with J or better when accuracy matters.

Read the body markings: a number tells you the value (using the three-digit code), a letter beside it gives tolerance, and a separate code or color marks the temperature characteristic (X7R, Y5V, NPO, etc.). For example, 104K Z5U means 100 nF ±10% with a wide temperature drift. The dielectric type matters in real installations — Y5V capacitors lose much of their value when warm, which has caused failures in summer in panel-mounted electronics.

Yes, exactly the same. 100 nF = 0.1 µF = 100,000 pF. The naming just shifts based on which decade the value lands in. Engineers in datasheets often write 0.1 µF, while schematic designers prefer 100 nF because it avoids decimal points. Both are correct, both refer to the same component. I encourage juniors to use nanofarads in their schematics to keep the numbers clean, but to read either form fluently.

Voltage rating is normally printed separately, not encoded in the same way as capacitance. You will see something like 50V, 100V, or 1KV stamped on the body. Some calculators allow you to enter the voltage label so the tool can flag mismatches. Always pick a capacitor rated at least 1.5 to 2 times your circuit voltage. We had a 25V capacitor pop on a 24V rail because of a switching spike — a 50V part would have survived.