Capacitor Code Calculator
This capacitor code calculator decodes the three-digit number printed on small ceramic and film capacitors and returns the capacitance in picofarads, nanofarads and microfarads. The code works just like the resistor color scheme but in printed digits: the first two figures are the significant digits and the third is the number of zeros to append, that is the power-of-ten multiplier, with the whole value expressed in picofarads. So a capacitor marked 104 reads as 10 followed by four zeros, which is 100,000 picofarads. The system follows the standard significant-digit and multiplier convention that the US National Institute of Standards and Technology and component references describe. Enter the three digits of the code and the calculator combines the first two as a two-digit number multiplied by ten raised to the third digit, then converts the picofarad result to nanofarads and microfarads. Use it to identify an unmarked part, confirm a substitution, or teach the marking system. The convention matches the resistor code: two significant digits followed by the count of trailing zeros, with the result always in picofarads. Every figure is computed deterministically from the three-digit code formula shown in full below, with a worked example that reconciles exactly to the calculator so you can follow each step yourself.
The first two digits are the value and the third is the number of zeros: code 104 means 10 followed by 4 zeros, which is 100,000 picofarads, equal to 100 nanofarads or 0.10 microfarad. The code reads directly in picofarads.
Capacitor code formula
C = ( d1 x 10 + d2 ) x 10 ^ d3 picofarads
d1 = first digit, d2 = second digit
d3 = third digit (number of zeros to append)
1,000 pF = 1 nF, 1,000,000 pF = 1 uF
The first two printed digits form a two-digit number in picofarads, and the third digit is how many zeros follow, that is the power of ten. The result is always in picofarads, which you then scale down to nanofarads or microfarads as convenient.
Worked example
Decode a ceramic capacitor printed with the code 104.
- two-digit value = 1 x 10 + 0 = 10
- multiplier = 10 ^ 4 = 10,000
- C = 10 x 10,000 = 100,000 picofarads
- 100,000 pF = 100 nF = 0.10 uF
Code 104 is 100,000 picofarads, which is 100 nanofarads or 0.10 microfarad. These are the calculator's default inputs, so the result above matches the widget exactly.
Common capacitor codes
A few frequently seen three-digit codes and their values.
| Code | Picofarads | Common form |
|---|---|---|
| 101 | 100 | 100 pF |
| 222 | 2,200 | 2.2 nF |
| 104 | 100,000 | 0.1 uF |
| 105 | 1,000,000 | 1 uF |
| 475 | 4,700,000 | 4.7 uF |
Units and measurement reference: US National Institute of Standards and Technology (NIST).
Capacitor Code Calculator: frequently asked questions
Why is the value in picofarads?
The three-digit capacitor code is defined in picofarads, the smallest common unit of capacitance. That keeps the printed numbers as whole digits even for very small parts. To read larger values, divide by 1,000 for nanofarads or by 1,000,000 for microfarads, which the calculator does for you.
What if the capacitor has only two digits?
A bare one or two digit marking is usually the value directly in picofarads, with no multiplier. For example a part marked 47 is simply 47 picofarads. The three-digit code with a trailing multiplier applies to most small ceramic and film capacitors but not to every component.
What does a letter after the code mean?
A trailing letter is the tolerance class. Common codes include J for 5 percent, K for 10 percent and M for 20 percent. The letter does not change the nominal capacitance this tool reports; it tells you how far the real value may deviate.
How do I read a code like 4R7?
When an R appears it acts as a decimal point, and the value is read directly in picofarads. So 4R7 means 4.7 picofarads. This format is used for small values below 10 picofarads where a three-zero multiplier scheme would not work. The calculator here handles the standard whole-multiplier codes.
Does this work for electrolytic capacitors?
Large electrolytic and tantalum capacitors are normally printed with the value and unit directly, such as 470 uF, rather than a three-digit picofarad code. This decoder is for the small ceramic and film capacitors that use the compact three-digit marking.
Official sources
- Electrical units and measurement reference: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.