Capacitor Code Calculator

Most small ceramic capacitors are physically too small to print their full value in plain text. A typical 0805 surface-mount part is barely 2 mm long, and even the larger through-hole ceramic discs and MLCCs (multi-layer ceramic capacitors) only have a few millimetres of room for any marking at all. To fit the value into that space, the electronics industry standardised a compact three-digit body code: the first two digits are the significant figures, the third digit is the power-of-ten multiplier, and the result is expressed in picofarads. So the marking 104 means "10 followed by four zeros", 100 000 pF, which is 100 nF, which is 0.1 µF. The marking 223 means "22 followed by three zeros", 22 000 pF = 22 nF. The marking 471 means "47 followed by one zero", 470 pF. This calculator decodes and encodes that system in both directions, shows the same value simultaneously in picofarads, nanofarads and microfarads, and includes the tolerance letter table and the alternate markings (R-notation, n-notation, plain integers, electrolytic direct markings) that appear on different capacitor families.

How to Use the Capacitor Code Calculator

1. Type the marking printed on the body of the capacitor into the Marking field. The most common form is a 3-digit code like 104, 223, 471. Other supported forms: a 3-digit code with a trailing tolerance letter like 104K or 223J, an n-notation like 4n7 (= 4.7 nF), an R-notation like 4R7 (= 4.7 pF), or a plain integer like 22 (= 22 pF).
2. (Optional) Pick the tolerance letter from the Tolerance dropdown. If you typed a trailing letter that the calculator recognises as a tolerance (B, C, D, F, G, J, K, M, Z), the dropdown auto-fills with that letter; if you did not type one, leave it blank.
3. Read the value in three units simultaneously, pF, nF, and µF, formatted without awkward trailing zeros or scientific notation in the typical range. With a tolerance letter, the calculator also shows the minimum and maximum capacitance implied by that tolerance (e.g. a 104K reading shows 90 000 pF to 110 000 pF).
4. Use the Quick codes row to load any common code (101, 102, 103, 104, 105, 223, 471, 472, 473, 22, 4n7, 4R7) for instant lookup. The active controls update as soon as you click.
5. switch to the Encode a value panel, enter a capacitance in pF, nF or µF using the unit dropdown, and read off the matching 3-digit code (with a default K ±10% tolerance letter).
6. The reference table at the bottom of the page shows the eleven most common 3-digit codes with their pF/nF/µF equivalents. Click any row to load that code into the decoder.

The Formula: Decoding a Three-Digit Body Code

The general decoding rule, taken from IEC 60062, is:

pF = (d₁ × 10 + d₂) × m

where d₁ is the first digit, d₂ is the second digit, and m is the multiplier set by the third digit A:

The two non-obvious multiplier rows, A = 8 and A = 9, are the classic gotcha. Reading them as ×10⁸ or ×10⁹ gives values that are ten billion or a hundred billion times too large, so the calculator handles them as explicit exceptions (× 0.01 and × 0.1) and the worked examples below call them out.

The formula assumes the third digit is a multiplier indicator, not a regular digit. There is no leading-zero 3-digit code: a 001 marking is unusual and would conventionally be written 1R0 (= 1.0 pF) instead.

Worked Examples

Example 1, Decoding 104. The first two digits are 1 and 0, the third digit is 4, so m = 10⁴. (1 × 10 + 0) × 10 000 = 10 × 10 000 = 100 000 pF. In nanofarads that is 100 000 / 1 000 = 100 nF. In microfarads that is 100 000 / 1 000 000 = 0.1 µF. With a K (±10%) tolerance, the part measures between 90 000 pF and 110 000 pF.

Example 2, Decoding 223. (2 × 10 + 2) × 10³ = 22 × 1 000 = 22 000 pF. That is 22 nF or 0.022 µF. This is one of the most common decoupling-capacitor values placed across the supply pins of logic chips.

Example 3, Decoding 229 (the A = 9 case). (2 × 10 + 2) × 0.1 = 22 × 0.1 = 2.2 pF. The third digit is 9, which is not ×10⁹, it is the special ×0.1 multiplier. 2.2 pF is a very small capacitance, typical of trimmer or high-frequency ceramic parts.

Example 4, Decoding 4n7 (n-notation). The letter n marks the decimal point and the unit. 4n7 = 4.7 nF = 4 700 pF. This format is used by some European and Japanese manufacturers and is also common on SMD ceramic parts with too little room for the standard three-digit code.

Example 5, Encoding 100 nF into a 3-digit code. 100 nF = 100 000 pF. The first two significant figures are 1 and 0; the third digit must be 4 (× 10⁴). The resulting code is 104. With the default K tolerance, the marking is 104K, indicating 100 nF ± 10% (90 nF to 110 nF actual).

Where Capacitor Codes Show Up

Decoupling and bypass capacitors on digital logic. A 100 nF (104) ceramic is the single most common capacitor in modern electronics: one sits within a few millimetres of every integrated circuit's supply pin to shunt high-frequency switching noise to ground. A 10 nF (103) and a 1 nF (102) often appear alongside it to cover different frequency bands. Reading the marking and verifying the value before placing the part is a routine check on prototype boards.

Filter and timing capacitors. RC filter cut-off frequencies and 555-timer / RC-oscillator periods are set by a resistor-capacitor pair, and the value of the capacitor is read directly off the 3-digit code. A filter with a 10 kΩ resistor and a 104 (100 nF) capacitor, for instance, has a cut-off around f = 1 / (2πRC) ≈ 160 Hz. If the capacitor is actually 473 (47 nF), the cut-off moves to roughly 340 Hz, a 2× change that is often the entire point of the part swap.

Sample-and-hold, ADC reference, and precision analog stages. Class-1 ceramic dielectrics such as C0G (also written NP0) hold their capacitance across temperature and voltage with single-digit-percentage drift. They are typically marked with the same 3-digit code as cheaper ceramics, but the part number on the reel identifies the dielectric class. The calculator does not decode the dielectric from the body marking, that information is on the packaging or in the supplier's part-number lookup.

Electrolytic capacitors. Aluminium and tantalum electrolytics are usually large enough to print the full value directly in µF, with a separate voltage rating (e.g. "10 µF 25 V") and a temperature code. The 3-digit body code is uncommon on electrolytics because the package is big enough to print the full value; the calculator's encode and decode paths handle the 3-digit code only, which matches the parts that actually use it (small ceramics).

Ceramic Dielectric Classes, Why the Same Marking Can Mean Different Things

The 3-digit code tells you the capacitance. It does not, on its own, tell you the dielectric, and the dielectric matters, because a 104 X7R capacitor and a 104 Y5V capacitor behave very differently with temperature and applied voltage.

• Class 1 dielectrics (C0G / NP0). Best stability. Capacitance changes very little across temperature (typically a few ppm/°C across −55 °C to +125 °C), and very little with applied DC voltage. Used in precision filters, oscillators, and timing. C0G and NP0 are two names for the same EIA-198 / IEC 60384 class.
• Class 2 dielectrics (X7R, X5R). Moderate stability. Capacitance can drop 10 to 20% from the marked value at full rated DC voltage, and across temperature the change is roughly ±15% over the operating range (the "7" in X7R is the lower-temperature limit code; "R" is the upper-temperature code). The workhorse dielectric for decoupling and general-purpose bypass caps.
• Class 3 dielectrics (Y5V, Z5U). High volumetric efficiency (a lot of capacitance in a small package) but poor stability, capacitance can change a factor of two or more across temperature and voltage. Common on cheap consumer-electronics bypass caps where the absolute value matters less than "is there enough capacitance to do the job".

The calculator handles all three classes identically for the value decoding, because the body marking only encodes the capacitance. Identifying the dielectric requires reading the part number or the manufacturer datasheet, which the calculator does not attempt.

Voltage Rating and Derating

Every capacitor has a maximum continuous DC voltage rating. Exceeding it can damage the part (especially in class-2 and class-3 ceramics, where dielectric breakdown is irreversible). The 3-digit body marking does not encode the voltage rating, it is on the part packaging, the reel label, or a separate line of the marking. Common ratings for small ceramics are 16 V, 25 V, 50 V, and 100 V. Derating is the practice of operating the capacitor well below its rated voltage, typically at half or less, to extend lifetime and reduce the risk of failure. A 50 V-rated capacitor on a 12 V rail is operating with substantial derating; the same capacitor directly across a 48 V rail has none.

Alternate Markings, n, R, and Direct

The calculator accepts several non-3-digit formats because capacitors are marked inconsistently across manufacturers and package families.

• Plain integer (1 or 2 digits): interpreted as pF directly. 22 means 22 pF. Common on small through-hole ceramics where the 3-digit code would be more confusing than a plain number.
• R notation: the letter R marks the decimal point, with the rest of the digits in pF. 4R7 = 4.7 pF. 2R2 = 2.2 pF. Common on small-value ceramics (1 pF to a few hundred pF).
• n notation: the letter n marks the decimal point, with the rest of the digits in nF. 4n7 = 4.7 nF = 4 700 pF. 2n2 = 2.2 nF = 2 200 pF. Common on European SMD ceramics.
• µ notation (rare on ceramics, more common on some tantalum markings): the letter µ (or "u" in plain ASCII) marks the decimal point in µF. 1u0 = 1.0 µF.
• Direct marking on electrolytics: the full value is printed ("10 µF", "100 µF", "470 µF") together with a voltage rating ("25 V") and sometimes a temperature code or polarity stripe. The 3-digit body code is not used here because the part is large enough for the full text.

Tolerance Letters (IEC 60062 Single-Letter Table)

A trailing letter on the marking indicates tolerance. The single-letter table from IEC 60062 is:

The absolute tolerances (B, C, D) are used on small pF values where a percent tolerance would be tighter than the part itself; on a 5 pF capacitor, ±1% would be ±0.05 pF, which is finer than B (±0.10 pF) and makes no engineering sense. The asymmetric Z is included because many cheap ceramics really do drift that much across temperature and voltage, a 104Z marking is honest about the part's behaviour.

Common Mistakes

Reading the third digit as a power of ten in every case. Treating A = 8 as ×10⁸ instead of ×0.01 gives an answer that is ten billion times too large. A 229 part is 2.2 pF, not 22 × 10⁹ pF.

Confusing pF with nF. A 104 is 100 nF, not 100 pF, the third-digit rule lands you four orders of magnitude higher than a casual reading. Always check both the numeric value and the unit before placing a part.

Assuming K tolerance is the only option. K (±10%) is the most common, but M (±20%), J (±5%), F (±1%), and Z (+80%/−20%) all appear on real parts. For timing and filter applications where the absolute capacitance matters, J or F is preferred; for decoupling where the exact value matters less, K or M is fine.

Ignoring the dielectric class. A 104 X7R and a 104 Y5V are both 100 nF at zero DC bias, but at full rated voltage the Y5V part may only deliver 20 to 30% of its marked value. If the circuit depends on the marked capacitance, choose the dielectric class with care, the calculator decodes the value, but it cannot decode the dielectric from the body marking.

Using the wrong marking convention across manufacturers. Some manufacturers use 3-digit codes exclusively, others use R-notation or n-notation, and a few mix them. When in doubt, read the part-number on the reel or the supplier datasheet and verify with an LCR meter before relying on the marked value in a production circuit.

Frequently Asked Questions

What does the 3-digit code 104 mean on a capacitor?

104 is the most common capacitor marking you will see. Following the IEC 60062 rule, the first two digits are the significant figures (1 and 0), and the third digit (4) is the number of zeros to append. So 104 means 10 followed by four zeros, 100 000 pF, which is 100 nF, which is 0.1 µF. A 104K is the same value with a ±10% tolerance, so the actual capacitance falls between 90 nF and 110 nF.

Why are some capacitors marked with three digits and others with a plain number?

The 3-digit code exists because small ceramic and film capacitors are too small to print their full value in plain text, a 2 mm × 1.25 mm surface-mount part has only a few square millimetres of marking area, and "100 000 pF" would not fit. The 3-digit code is a compact way to encode the same information. Larger capacitors (electrolytics, tantalum, and physically big ceramics) have enough room to print the value directly, often together with a voltage rating, so they use direct markings instead.

What is the difference between C0G, X7R, and Y5V ceramic capacitors?

C0G (also called NP0) is a class-1 dielectric, very stable across temperature (single-digit ppm/°C) and with negligible change under DC bias. X7R is a class-2 dielectric, moderate stability, with capacitance dropping roughly 10 to 20% at full rated DC voltage and ±15% across the operating temperature range. Y5V is a class-3 dielectric, high volumetric efficiency but poor stability, with capacitance potentially changing by a factor of two or more across temperature and voltage. For precision timing and filters use C0G; for general decoupling use X7R; for cheap bypass applications where the absolute value matters less than "enough capacitance" use Y5V.

Can I use a higher-voltage capacitor in place of a lower-voltage one?

Yes, using a capacitor with a higher voltage rating than required is always safe and is in fact recommended practice (derating). The only trade-off is physical size: higher voltage ratings usually mean a larger package. Going the other way (using a lower-rated capacitor above its rated voltage) can damage the part and is not safe.

What is the most common tolerance letter on ceramic capacitors?

K (±10%) is by far the most common tolerance letter on general-purpose ceramics. J (±5%) and F (±1%) appear on tighter-spec parts (typically C0G / NP0). M (±20%) and Z (+80%/−20%) appear on cheap bypass caps where the precise value is not critical. The letter is printed after the value code, so 104K means 100 nF ±10%, 104J means 100 nF ±5%, and so on.

can the Capacitor Code Calculator be used for professional or commercial purposes?

yes, the Capacitor Code Calculator provides mathematically correct results that are suitable for professional, commercial, and educational use. For the Capacitor Code Calculator, For the Capacitor Code Calculator, For high-stakes applications (medical, legal, financial), verify results with a domain expert. For the Capacitor Code Calculator, the Capacitor Code Calculator formulas used are well-established and validated against reference standards.

For the Capacitor Code Calculator, How often are the underlying formulas updated?

For the Capacitor Code Calculator, the Capacitor Code Calculator formulas are based on established scientific, mathematical, or industry-standard references and rarely require updates. when standards change, the Capacitor Code Calculator is updated to reflect the current authoritative source. For the Capacitor Code Calculator, For the Capacitor Code Calculator, Each calculator's references section lists the specific sources used.

References

• IEC 60062, Marking codes for resistors and capacitors. International standard defining the 3-digit body code system and the single-letter tolerance table (B, C, D, F, G, J, K, M, Z) used on small capacitors and resistors.
• IEC 60384, Fixed capacitors for use in electronic equipment. The series of international standards covering capacitor test methods, marking, and classification. Section IEC 60384-8 / IEC 60384-9 / IEC 60384-10 / IEC 60384-21 cover ceramic capacitors (class 1, class 2, class 3) and define the dielectric codes used by EIA-198.
• EIA-198, Ceramic Dielectric Capacitor Classes. The Electronic Industries Alliance standard that defines the class codes (C0G/NP0, X7R, X5R, Y5V, Z5U) and their associated temperature characteristics and voltage coefficients. EIA-198 is the North American counterpart to the relevant sections of IEC 60384.
• ISO 80000-1, Quantities and units, Part 1: General. The international standard that defines the SI, including the farad (F) as the derived unit of capacitance (1 F = 1 C/V).
• IEC 60617, Graphical symbols for diagrams. The international standard for component symbols used on schematics; the capacitor symbol is defined here.