How do I read the number on a capacitor?
- Find the value code. On small ceramic and film capacitors it is usually three digits, like 104. The first two digits are the figures, the third is how many zeros follow. The answer is in picofarads (pF).
- Turn picofarads into nF or µF. 1,000 pF = 1 nF and 1,000 nF = 1 µF. So 104 = 100,000 pF = 100 nF = 0.1 µF.
- Read the letter after it. One letter right after the code is the tolerance: J ±5 %, K ±10 %, M ±20 %. It is not kilo or mega.
- Look for the voltage. It is printed in volts (50V, 1KV, 2kV) or, on film parts, as a short code like 2A (100 V). Use a part rated well above the voltage in your circuit.
Ceramic disc, 104100 nF (0.1 µF). The classic decoupling capacitor next to every chip. Film box, 2A104J100 V (2A), 100 nF (104), ±5 % (J). Voltage code first, as many film boxes print it. Electrolytic, 10µF 25VValue and voltage in full. The light stripe with minus signs marks the minus lead.
Two other ways the value is written
A plain number with a decimal point is microfarads: 0.1 or .1 means 0.1 µF (100 nF), .047 means 47 nF. A plain whole number of one or two digits is picofarads: 22 means 22 pF.
Small values may use R as the decimal point: 1R0 is 1.0 pF and 4R7 is 4.7 pF. Codes ending in 9 or 8 do the same job: the 9 means ×0.1 and the 8 means ×0.01, so 339 is 3.3 pF and 478 is 0.47 pF.
Can I see a few worked out?
Each one is read by the same engine as the calculator above.
100 nF
104: First two digits 10, then 4 zeros: 10 × 10⁴ pF = 100,000 pF.
10 nF ±5 %
103: First two digits 10, then 3 zeros: 10 × 10³ pF = 10,000 pF.
J: Tolerance ±5 %: the real value may be anything from 9.5 nF to 10.5 nF.
2.2 nF ±10 %
222: First two digits 22, then 2 zeros: 22 × 10² pF = 2,200 pF.
K: Tolerance ±10 %: the real value may be anything from 1.98 nF to 2.42 nF.
2kV: Rated voltage 2,000 V: the most voltage it is made to take all the time. Use one rated well above your circuit.
4.7 nF
4n7: The n stands for nanofarads and sits where the decimal point goes: 4.7 nF.
What are the most common capacitor codes?
The 30 codes you meet most, from 10 pF to 10 µF, with the value in all three units and the IEC 60062 letter code that means the same.
| Code | Picofarads (pF) | Nanofarads (nF) | Microfarads (µF) | Letter code |
|---|---|---|---|---|
| 100 | 10 pF | 0.01 nF | 0.00001 µF | 10p |
| 150 | 15 pF | 0.015 nF | 0.000015 µF | 15p |
| 220 | 22 pF | 0.022 nF | 0.000022 µF | 22p |
| 330 | 33 pF | 0.033 nF | 0.000033 µF | 33p |
| 470 | 47 pF | 0.047 nF | 0.000047 µF | 47p |
| 680 | 68 pF | 0.068 nF | 0.000068 µF | 68p |
| 101 | 100 pF | 0.1 nF | 0.0001 µF | 100p |
| 151 | 150 pF | 0.15 nF | 0.00015 µF | 150p |
| 221 | 220 pF | 0.22 nF | 0.00022 µF | 220p |
| 331 | 330 pF | 0.33 nF | 0.00033 µF | 330p |
| 471 | 470 pF | 0.47 nF | 0.00047 µF | 470p |
| 681 | 680 pF | 0.68 nF | 0.00068 µF | 680p |
| 102 | 1,000 pF | 1 nF | 0.001 µF | 1n0 |
| 152 | 1,500 pF | 1.5 nF | 0.0015 µF | 1n5 |
| 222 | 2,200 pF | 2.2 nF | 0.0022 µF | 2n2 |
| 332 | 3,300 pF | 3.3 nF | 0.0033 µF | 3n3 |
| 472 | 4,700 pF | 4.7 nF | 0.0047 µF | 4n7 |
| 682 | 6,800 pF | 6.8 nF | 0.0068 µF | 6n8 |
| 103 | 10,000 pF | 10 nF | 0.01 µF | 10n |
| 153 | 15,000 pF | 15 nF | 0.015 µF | 15n |
| 223 | 22,000 pF | 22 nF | 0.022 µF | 22n |
| 333 | 33,000 pF | 33 nF | 0.033 µF | 33n |
| 473 | 47,000 pF | 47 nF | 0.047 µF | 47n |
| 683 | 68,000 pF | 68 nF | 0.068 µF | 68n |
| 104 | 100,000 pF | 100 nF | 0.1 µF | 100n |
| 224 | 220,000 pF | 220 nF | 0.22 µF | 220n |
| 474 | 470,000 pF | 470 nF | 0.47 µF | 470n |
| 105 | 1,000,000 pF | 1,000 nF | 1 µF | 1µ0 |
| 225 | 2,200,000 pF | 2,200 nF | 2.2 µF | 2µ2 |
| 106 | 10,000,000 pF | 10,000 nF | 10 µF | 10µ |
Watch the codes that end in 0: 100 is 10 pF, not 100 pF, because the last digit counts zeros and 0 adds none. Small discs often print just the number (10, 22, 47) for values under 100 pF.
What does the letter after the code mean?
It is the tolerance: how far the real value may be from the printed one. Under 10 pF, IEC 60062 gives B, C, D, F and G in picofarads, because a percent of a tiny value is too small to make.
| Letter | Under 10 pF | 10 pF and up | Where you see it |
|---|---|---|---|
| B | ±0.1 pF | ±0.1 % | Very small precision ceramics |
| C | ±0.25 pF | ±0.25 % | Small C0G / NP0 ceramics |
| D | ±0.5 pF | ±0.5 % | Small C0G / NP0 ceramics |
| F | ±1 pF | ±1 % | Precision film and C0G |
| G | ±2 pF | ±2 % | Precision film and C0G |
| J | ±5 % | ±5 % | Film boxes, C0G discs |
| K | ±10 % | ±10 % | Film boxes, X7R ceramics |
| M | ±20 % | ±20 % | General ceramics, film |
| Z | +80 % / −20 % | +80 % / −20 % | Cheap Y5V / Z5U discs |
Z means the real value may be up to 80 % higher or 20 % lower than printed. A 104Z disc can measure anything from 80 nF to 180 nF: fine for smoothing a supply, wrong for a timer.
What do the n, p, µ and R in a code mean?
IEC 60062 has a second way to write the value: the unit letter takes the place of the decimal point, so a worn or missed dot cannot change the value. p is picofarads, n nanofarads and µ (often printed u) microfarads.
4n7= 4.7 nF47n= 47 nFn47= 0.47 nF100n= 100 nF2µ2= 2.2 µF4p7= 4.7 pF1R0= 1.0 pF
Which one will I find on the part?
Ceramic discs and most small parts use the three-digit code (472). Film boxes from European makers often use the letter code (4n7) or print the value in full. Electrolytic cans print it in full (10µF). The calculator reads all of them and, in “Find the code”, lists each one for your value.
What do 1H, 2A and 2J mean?
On film and some electrolytic capacitors the rated voltage is a digit and a letter. The digit is the power of ten, the letter the figures: 2A = 1.0 × 100 = 100 V. This code is shared by the makers and printed in their catalogues; it is not part of IEC 60062.
| Code | Rated voltage | How it is worked out |
|---|---|---|
| 0G | 4 V | 4 × 1 |
| 0J | 6.3 V | 6.3 × 1 |
| 1A | 10 V | 1 × 10 |
| 1C | 16 V | 1.6 × 10 |
| 1E | 25 V | 2.5 × 10 |
| 1V | 35 V | 3.5 × 10 |
| 1H | 50 V | 5 × 10 |
| 1J | 63 V | 6.3 × 10 |
| 1K | 80 V | 8 × 10 |
| 2A | 100 V | 1 × 100 |
| 2C | 160 V | 1.6 × 100 |
| 2D | 200 V | 2 × 100 |
| 2E | 250 V | 2.5 × 100 |
| 2F | 315 V | 3.15 × 100 |
| 2V | 350 V | 3.5 × 100 |
| 2G | 400 V | 4 × 100 |
| 2W | 450 V | 4.5 × 100 |
| 2J | 630 V | 6.3 × 100 |
| 3A | 1,000 V | 1 × 1,000 |
Voltage printed in full
Ceramic discs usually print the voltage in full: 50V, 100V, 1KV, 2KV or 3KV. Discs with no voltage on them are often 50 V types; treat them as low-voltage parts unless the datasheet says more. A letter code read as volts only works next to a value: on its own, 2A is not a capacitance.
X7R, C0G, Y5V: the ceramic type
| Code | What it tells you |
|---|---|
| C0G | Class 1 ceramic (also written NP0): the value barely moves with temperature (0 ±30 ppm/°C). Best for timing and filters. |
| X5R | Class 2 ceramic: the value stays within ±15 % from −55 °C to +85 °C. It drops with DC voltage. |
| X6S | Class 2 ceramic: the value stays within ±22 % from −55 °C to +105 °C. |
| X7R | Class 2 ceramic: the value stays within ±15 % from −55 °C to +125 °C. It drops with DC voltage. |
| X7S | Class 2 ceramic: the value stays within ±22 % from −55 °C to +125 °C. |
| X8R | Class 2 ceramic: the value stays within ±15 % from −55 °C to +150 °C. |
| Y5V | Class 2 ceramic: the value may move +22 % / −82 % from −30 °C to +85 °C. Cheap decoupling only. |
| Z5U | Class 2 ceramic: the value may move +22 % / −56 % from +10 °C to +85 °C. Cheap decoupling only. |
How do I read an electrolytic capacitor?
- Value: printed in full in microfarads, like 10µF, 470µF or 4.7µF. Older cans write MFD for µF.
- Voltage: printed in full, like 25V, or as a code like 1E (25 V). This is the most it may ever see. Pick one rated at least about 20 % above your supply.
- The minus stripe: the light band with minus signs (−) runs down the side of the leg that goes to minus (ground). On a new part that leg is also the shorter one.
- Temperature: 85°C or 105°C is the hottest it is made for. 105°C parts last longer near warm parts.
Get the direction right
An electrolytic capacitor fitted the wrong way round, or run above its voltage, heats up and can bulge, leak or burst. Check the stripe against the minus mark on the board before you solder. On flat metal-can surface-mount parts the black mark on the top is minus.
Tantalum capacitors are the opposite: on a tantalum part the stripe or bar marks the plus side. Check which kind you have before you trust a stripe.
What do people often get wrong?
Reading 100 as 100 pF
The last digit counts zeros. 100 is 10, then no zeros: 10 pF. 101 is 100 pF.
Taking K for kilo
A K right after the code is ±10 % tolerance. 104K is 100 nF ±10 %, not 104 thousand of anything.
Reading the part upside down
Turned round, 106 looks like 901. If a code gives a strange value or ends in 7, turn the part and read again.
Mixing up nF and µF
1 µF is 1,000 nF. 0.1 µF and 100 nF are the same part; so are 0.01 µF and 10 nF.
Short answers to common questions
What does 104 mean on a capacitor?
104 is 100,000 pF, which is 100 nF or 0.1 µF. The first two digits are the figures (10) and the last digit is how many zeros follow (4), in picofarads.
What value is a 103 capacitor?
103 is 10,000 pF = 10 nF = 0.01 µF. In the same way 102 is 1 nF, 473 is 47 nF and 105 is 1 µF.
What do J, K and M after the number mean?
They are tolerance letters from IEC 60062: J is ±5 %, K is ±10 % and M is ±20 %. So 103J is 10 nF that may really be anywhere from 9.5 nF to 10.5 nF. The K is not kilo and the M is not mega.
What does 222K 2kV mean?
222 is 2,200 pF (2.2 nF), K is ±10 % and 2kV means it is rated for 2,000 volts. It is a typical high-voltage ceramic disc.
What does 4n7 mean on a capacitor?
4n7 is 4.7 nF. In this IEC 60062 letter code the letter is the unit and stands where the decimal point goes: 4n7 = 4.7 nF, 47n = 47 nF, n47 = 0.47 nF, 2u2 (or 2µ2) = 2.2 µF and 4p7 = 4.7 pF.
Is 0.1 µF the same as 100 nF and 104?
Yes. 0.1 µF, 100 nF, 100,000 pF and the code 104 are all the same capacitance. A plain number with a decimal point on a ceramic or film capacitor, like 0.1 or .047, is in microfarads.
What does 1R0 or 4R7 mean on a small capacitor?
The R marks the decimal point and the value is in picofarads: 1R0 is 1.0 pF and 4R7 is 4.7 pF. Some parts write these small values as 109 and 479 instead, where a last digit 9 means ×0.1.
What do 1H, 2A or 2J mean on a film capacitor?
They are voltage codes. The digit is the power of ten and the letter the figures: 1H = 50 V, 2A = 100 V, 2E = 250 V, 2G = 400 V, 2J = 630 V. This code is shared by the makers rather than set by IEC 60062, so check the datasheet when in doubt.
Which leg of an electrolytic capacitor is negative?
The leg on the side of the printed stripe (usually a light band with minus signs) is negative, and on a new part it is the shorter leg. On a circuit board the minus side of the outline is often shaded.
Can I replace a capacitor with one rated for a higher voltage?
Usually yes: keep the same capacitance and use the same or a higher voltage. The part may be bigger. Never go lower. For mains safety capacitors (marked X1, X2, Y1, Y2) use the same safety class or better.
Why does my meter read a different value than the code?
Tolerance first: a K part may be 10 % off and a Z part +80 % / −20 %. Ceramic capacitors marked X7R, X5R, Y5V or Z5U also lose capacitance with DC voltage, heat and age. C0G (NP0) and film parts stay close to their marking.
Can I use the capacitor pictures?
Yes. Download the PNG and use it in notes, lessons or posts. The wirecora.com mark along the bottom stays in the picture.
How do we check the calculator?
Value and tolerance codes follow IEC 60062:2016+A1:2019, the international standard for marking codes on resistors and capacitors. In plain words it says: the three-digit code is two figures and a count of zeros, in picofarads; a unit letter (p, n, µ) may stand in for the decimal point; and one letter gives the tolerance, in picofarads under 10 pF and in percent from 10 pF.
Three things you see on real parts are not in that standard, and we say so where they appear: a last digit 8 or 9 (×0.01 and ×0.1) and R as a decimal point for tiny values, the two-character voltage codes (2A, 1H) the makers share, and the ceramic type codes (X7R, C0G) from the EIA. The page shows no ads and sets no cookies.
Logic check: every three-digit code from 108 to 996 is decoded and turned back into the same code, and each answer on this page is worked out by the calculator's own engine with exact whole-number maths.