Capacitor Code Calculator

Decode the markings on a ceramic, film or SMD capacitor into picofarads, nanofarads and microfarads - and convert a value back into the printed code. Handles the 3-digit IEC code, 4-digit precision and SMD codes, R-notation, letter notation and EIA-198 SMD codes, with tolerance letters.

Enter a capacitor code

Method based on IEC 60062 / EIA-198 · reviewed June 2026 · method rev 1.0

How the 3-digit code works

The first two digits are the significant figures; the third is how many zeros to add, giving the value in picofarads. So 104 is 10 followed by four zeros = 100,000 pF = 100 nF = 0.1 uF.

Most ceramic and film capacitors are too small to print a full value, so they use a 3-digit code defined in IEC 60062. The first two digits are the significant figures and the third is a multiplier - the number of zeros to add. The result is always in picofarads (pF).

So 104 is 10 followed by four zeros = 100,000 pF = 100 nF = 0.1 uF, the ubiquitous decoupling capacitor. 222 is 22 followed by two zeros = 2,200 pF = 2.2 nF. A third digit of 0 means no zeros, so 330 is just 33 pF. Two special multipliers exist: 8 means times 0.01 and 9 means times 0.1, so 159 is 1.5 pF.

Four-digit codes

Precision parts and many surface-mount capacitors use a 4-digit code: the first three digits are the significant figures and the fourth is the multiplier. So 1002 is 100 followed by two zeros = 10,000 pF = 10 nF, and 4753 is 475 followed by three zeros = 475 nF. The same special multipliers apply, so a final 8 means times 0.01 and 9 means times 0.1. This tool reads 3-digit and 4-digit codes automatically; you do not need to pick a format.

R-notation and letter notation

Small values and schematic labels often put a letter where the decimal point goes, which avoids a lost decimal point on a tiny part. In R-notation the value is in picofarads and R is the point: 4R7 is 4.7 pF. In letter notation the letter is both the unit and the point: 4n7 is 4.7 nF, 100n is 100 nF, 0.1u is 0.1 uF, and 47p is 47 pF. The units are p (pF), n (nF), u or the micro sign (uF) and m (mF).

SMD capacitors use EIA-198

Surface-mount capacitors are usually too small for the 3-digit code, so they use the EIA-198 system: two significant digits followed by a single letter multiplier. The letters are R = times 0.01, A = 1, B = 10, C = 100, D = 1,000, E = 10,000 and F = 100,000, with the result in picofarads. So 22C is 22 times 100 = 2,200 pF = 2.2 nF, and 47D is 47,000 pF = 47 nF. Note that a marking like 0805 or 0603 is the case size, not the value - the value still has to come from the printed code, a measurement or the reel.

Tolerance letters

A letter after the value code is the tolerance. The common ones are F = plus or minus 1%, G = 2%, J = 5%, K = 10% and M = 20%; very small capacitors use B, C and D for fixed picofarad tolerances. So 104K is 100 nF at plus or minus 10%. For timing circuits such as RC oscillators and filters, use J or tighter; for decoupling, K or M is fine and cheaper.

Common capacitor codes

Code	pF	nF	uF
100	10	0.01	0.00001
220	22	0.022	0.000022
470	47	0.047	0.000047
101	100	0.1	0.0001
102	1,000	1	0.001
222	2,200	2.2	0.0022
103	10,000	10	0.01
473	47,000	47	0.047
104	100,000	100	0.1
224	220,000	220	0.22
105	1,000,000	1,000	1
475	4,700,000	4,700	4.7
106	10,000,000	10,000	10
226	22,000,000	22,000	22

Values are computed from the IEC 60062 rule, not copied from a manufacturer table. The code gives the nominal value only - always confirm the voltage rating and dielectric separately.

The code is not the whole part

The value code never includes the voltage rating, the polarity or the dielectric. Dielectric matters in real circuits: C0G / NP0 is very stable, while Class II ceramics such as X7R, X5R and especially Y5V lose a large fraction of their capacitance under DC bias and temperature - regardless of the printed tolerance. A 104 marked X7R can sit well below 100 nF in service, which has caused real failures in timing and filtering. Decode the value, then read the datasheet before you commit.

Where engineers use this

Reading parts off a reel or board

Turning a tiny ceramic marking such as 104 or 4n7 into a real value when the part number has rubbed off or the reel is unlabelled.

Bench repair and substitution

Decoding the marking on a failed capacitor to find a like-for-like replacement, then checking tolerance and dielectric before fitting.

BOM and schematic checks

Confirming that the value on the schematic matches the printed code on the assembled board, especially for decoupling 104 (0.1 uF) and timing parts.

Frequently asked questions

What does 104 mean on a capacitor?

104 is the 3-digit IEC code for 10 times ten to the fourth picofarads: 100,000 pF, which is 100 nF or 0.1 uF. It is the most common decoupling capacitor in digital electronics.

What does the letter after the code mean?

It is the tolerance. F is plus or minus 1%, G is 2%, J is 5%, K is 10% and M is 20%. So 104K is 100 nF at plus or minus 10%.

What does 4R7 or 4n7 mean?

Both put the letter where the decimal point goes. 4R7 is 4.7 pF (R-notation, value in pF). 4n7 is 4.7 nF (letter notation, the n marks nanofarads). 100n is 100 nF and 0.1u is 0.1 uF.

What does a 4-digit code like 1002 mean?

Four-digit codes carry three significant figures and a final multiplier digit, used where tighter tolerance or a wider value range is needed. So 1002 is 100 followed by two zeros = 10,000 pF = 10 nF, and 4753 is 475 followed by three zeros = 475 nF. The 8 and 9 special multipliers still apply.

How do I read an SMD capacitor code like 22C?

Small SMD capacitors use EIA-198: two significant digits then a letter multiplier. 22C is 22 times 100 = 2,200 pF = 2.2 nF. The letters run R = times 0.01, A = 1, B = 10, C = 100, D = 1,000, E = 10,000, F = 100,000.

Does the code tell me the voltage rating?

No. The value code never includes the voltage rating or the dielectric. Class II ceramics such as X7R and Y5V also lose capacitance under DC bias and temperature, so the working value can sit below the marked one. Check the datasheet for timing and filter work.

How this relates to other tools

Standard / tool	Relationship	What it means
AWG to mm converter	commonly used with	Both turn a printed component marking into a usable number on the bench.
PCB trace width calculator	related calculator	Decoupling capacitors such as 104 sit on the power traces this tool sizes.

Related tools and standards

AWG to mm converter PCB trace width calculator mAh to Wh calculator

Sources: IEC 60062, Marking codes for resistors and capacitors · EIA-198 (RS-198), standard marking for capacitor value and tolerance, published by ECIA. Verify against the current edition.