Capacitor Code Calculator
Decode ceramic and film capacitor codes like 104, 4R7 or 2A104J into pF, nF and µF with tolerance and voltage, encode values back, and read X7R or C0G.
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About this toolWhat is the Capacitor Code Calculator?
Small ceramic and film capacitors are too small to print "100 nF 100 V ±5%" on, so manufacturers use a short code instead. This capacitor code calculator reads that code: type 104 and it shows 100,000 pF, 100 nF and 0.1 µF at once; type 2A104J and it adds the 100 V rating and the ±5% tolerance with the minimum and maximum value that tolerance allows.
It also works in reverse. Enter a value in pF, nF, µF or mF and get the three-digit code, plus the full marking with a tolerance letter and an EIA voltage code if you pick them. Values that cannot be shown exactly in two significant figures are rounded, and the calculator says so.
A third panel decodes the dielectric code printed on the reel or in the part number, such as X7R, X5R, Y5V or C0G, into its temperature range and the capacitance change it allows, and reference tables list every common voltage and tolerance letter.
- Three-digit, R-notation and two-digit codes, including 8 and 9 multipliers
- Tolerance letters with minimum and maximum values
- EIA voltage codes such as 1H, 2A and 2J, at the front or end
- Value to code with optional tolerance and voltage letters
- X7R, X5R, Y5V, C0G and other dielectric codes decoded
- pF, nF and µF shown side by side
How to use the Capacitor Code Calculator
- Type the code printed on the capacitor into Code to value, for example 104, 473K, 2A104J or 104K 2A. Case and spaces do not matter.
- Read the value in picofarads, nanofarads and microfarads, the tolerance with its minimum and maximum, and the rated voltage if a voltage code was included.
- To go the other way, enter a capacitance and unit in Value to code, then optionally choose a tolerance letter and voltage code to build a full marking.
- Type a dielectric code such as X7R or C0G to see its class, temperature range and allowed change.
- Use the reference tables when reading a datasheet or ordering code.
Worked examples
The most common code
Input
104
Output
100,000 pF = 100 nF = 0.1 µF
10 followed by four zeros, in picofarads. This is the classic decoupling capacitor next to almost every IC.
A film capacitor with voltage and tolerance
Input
2A104J
Output
100 nF, ±5% (95 to 105 nF), 100 V DC
2A is the EIA code for 100 V (1.0 × 10²), 104 is 100 nF and J is ±5%. Polyester box capacitors are often marked this way.
A ceramic disc with a 50 V code
Input
1H223K
Output
22 nF, ±10% (19.8 to 24.2 nF), 50 V DC
1H is 5.0 × 10 = 50 V. Reading the 1H as part of the value is a common mistake; the value always has two significant digits then a multiplier.
Encoding a calculated value
Input
15.9155 nF
Output
Code 163, rounded to 16 nF
Two significant figures cannot hold 15.9155, so the code rounds to 16 nF. In practice you would buy the nearest E12 part, 15 nF (code 153).
Background and insight
The three-digit code is the same scheme as resistor colour bands, written in digits: the first two digits are significant figures and the third is the number of zeros to add, with the answer in picofarads. 104 is 10 followed by four zeros, 100,000 pF, which is 100 nF or 0.1 µF. 472 is 4,700 pF (4.7 nF), and 101 is 100 pF. A third digit of 9 means multiply by 0.1 and 8 means multiply by 0.01, so 229 is 2.2 pF. Below 10 pF the letter R often marks the decimal point instead: 4R7 is 4.7 pF. One or two digits with no multiplier, such as 47, are read directly as picofarads.
A letter after the digits is the tolerance, from IEC 60062 and the EIA tables: J is ±5%, K ±10%, M ±20%, F ±1%, G ±2%, and Z is +80% / −20%, a wide asymmetric tolerance common on old Y5V decoupling parts. B, C and D are absolute tolerances (±0.1, ±0.25 and ±0.5 pF) used on small values where a percentage would be meaningless. A digit-and-letter pair in front of the value, such as 2A or 1H, is the EIA voltage code: the digit is a power of ten and the letter a mantissa (A 1.0, C 1.6, E 2.5, V 3.5, G 4.0, H 5.0, J 6.3, K 8.0), so 1H is 50 V and 2J is 630 V. The same letters appear in aluminium electrolytic part numbers, for example the "1V" in a 35 V part.
Dielectric codes come from EIA-198. Class 1 codes such as C0G (also written NP0) describe a temperature coefficient: C0G is 0 ±30 ppm/°C, essentially no drift, used for filters and oscillators. Class 2 codes describe a temperature range and a permitted change: X7R works from −55 °C to +125 °C and stays within ±15%, X5R covers −55 °C to +85 °C at ±15%, and Y5V covers −30 °C to +85 °C but may change by +22% to −82%. Class 2 parts also lose capacitance with applied DC voltage and with age, which no code shows; the manufacturer's DC bias curve does. Decoding tables here follow Vishay and Knowles application notes on EIA-198.
Common use cases
Identifying parts on a board
Read the codes on ceramic discs and film capacitors when repairing or reverse-engineering a circuit.
Sorting a parts drawer
Convert unlabelled codes into nF and µF so parts can be filed by value.
Ordering replacement parts
Turn a schematic value into the code and voltage rating a supplier listing will show.
Choosing a dielectric
Check whether X7R, X5R or C0G suits a filter, timing or decoupling job before buying.
Tips and limitations
- Electrolytic capacitors are usually printed in full (for example 470 µF 25 V), so codes are mostly found on ceramic, film and tantalum parts.
- On surface-mount ceramics there is normally no marking at all; the value is only on the reel label and part number.
- A three-digit number on a tantalum capacitor uses the same scheme in picofarads: 106 is 10 µF.
- Pick a voltage rating at least 1.5 to 2 times the working voltage for ceramics, and more for X5R and Y5V parts, which lose capacitance under DC bias.
- If a "code" gives an odd answer, check whether the marking is a date code or a manufacturer logo instead.
Frequently asked questions
What does 104 mean on a capacitor?
10 followed by four zeros, in picofarads: 100,000 pF, which is 100 nF or 0.1 µF.
How do I read a capacitor code like 473?
Take the first two digits (47) and add the number of zeros given by the third digit (3): 47,000 pF, which is 47 nF or 0.047 µF.
What does the letter J, K or M after a capacitor code mean?
It is the tolerance. J is ±5%, K is ±10% and M is ±20%. A 104K capacitor can measure anywhere from 90 nF to 110 nF and still be in specification.
What voltage is 2A on a capacitor?
100 V. In the EIA voltage code the digit is a power of ten and the letter a value: A is 1.0, so 2A is 1.0 × 100 = 100 V. 1H is 50 V and 2J is 630 V.
What is the difference between X7R and C0G capacitors?
C0G (NP0) is a class 1 dielectric whose capacitance barely changes with temperature, voltage or age; it suits filters and timing but is only available in small values. X7R is class 2: much higher capacitance per size, but it can change by ±15% over −55 to +125 °C and loses more under DC bias.
How many nF is 0.1 µF?
100 nF. 1 µF = 1,000 nF = 1,000,000 pF, so 0.1 µF is 100 nF or 100,000 pF, marked 104.
What does 4R7 mean on a capacitor?
4.7 pF. The R marks the decimal point, which is how values below 10 pF are usually coded.
Is a 105 capacitor 1 µF?
Yes. 10 followed by five zeros is 1,000,000 pF, which is 1 µF.
Is there an in-depth guide to the Capacitor Code Calculator?
Yes. “Reading Capacitor Codes: 104, 2A104J, X7R and C0G Explained” covers the background, how it works, common pitfalls and worked examples. Read the full guide.
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