Capacitor Code Calculator

How to use

1. 1Pick a mode: Decode code to value to read a printed marking, or Build code from value to find the code for a target capacitance.
2. 2In Decode mode, type the code as printed (104, 103J, 4n7, 100 nF, X7R 105, 224K 50V). Letters and numbers can be mixed and the field is case-insensitive.
3. 3Read the capacitance in pF, nF, and uF, plus tolerance (when a letter is present), voltage rating (when a V tail is present), and the temperature characteristic (X7R, NP0, etc) when one is included.
4. 4In Build mode, type a target value with its unit (100 nF, 4.7 uF, 220 pF). The tool prints the 3-digit code, the EIA-198 letter-decimal code, and the nearest E6, E12, and E24 standard values.
5. 5Click Copy next to any row to grab the value, or use Copy summary to copy a one-block summary into your notes or a parts list.

About this tool

Capacitor Code Calculator reads the cryptic three or four character codes printed on ceramic disc, ceramic chip (SMD), tantalum, and EIA-198 capacitors and returns the value in picofarads, nanofarads, and microfarads, along with the tolerance, voltage rating, and the JEDEC ceramic class when the part includes a temperature characteristic. Decode mode handles every common marking format in a single field: 3-digit codes like 104 (10 with multiplier 10^4 picofarads, so 100,000 pF = 100 nF = 0.1 uF), the same code with a trailing tolerance letter like 104J (+/- 5%) or 224K (+/- 10%), short 1 or 2 digit codes like 47 or 22 that mark small ceramic discs in plain picofarads, EIA-198 letter-decimal codes like 4n7 and 1n0 where the unit letter (p, n, u, or the legacy R) sits in place of the decimal point, plain values with units like 100 nF or 0.1 uF, voltage tails like 50V or 1kV appended to any code, and ceramic temperature characteristic markings like X7R, NP0, C0G, X5R, Y5V, and Z5U that identify the dielectric class without changing the value. The tool shows a step-by-step decoding breakdown so you can see exactly how each character was interpreted, which is helpful when learning the code and for confirming that a marking on a board really is a capacitor rather than a resistor or inductor. Build mode runs the lookup in reverse: type a target capacitance like 100 nF, 4.7 uF, or 220 pF and the calculator synthesises the canonical 3-digit code (when the value fits the EIA form), the EIA-198 letter-decimal code, and the nearest preferred values from the IEC 60063 E6 (20%), E12 (10%), and E24 (5%) series so designers can confirm whether the value is a stocked component. The page includes a full tolerance letter reference table (F = 1%, G = 2%, J = 5%, K = 10%, M = 20%, B/C/D = absolute pF for sub-10-pF parts, P = -0/+100%, Z = -20/+80%), an explanation of every digit position in the 3-digit code (significant figures, exponent of 10 in picofarads, the special 8 = x0.01 and 9 = x0.1 EIA multipliers used for sub-picofarad markings), and a guide to the EIA-198 letter-decimal format used on premium ceramic and film capacitors. Useful for hobbyist electronics, robotics, audio and hi-fi repair, decoupling and bypass capacitor selection, filter design, EE coursework and labs, and any time you have a strip of unmarked capacitors or a board photograph and need to read or convert a value. Everything runs in your browser; no upload, no signup, no API calls.

Free to use. Works in your browser. No signup, no login.