Capacitor Code Calculator

How it works

Ceramic capacitors are commonly marked with a three-digit code in picofarads. The first two digits are the significant figures and the third is the number of zeros to add: 104 is 10 followed by four zeros, 100,000 pF, which is 100 nF or 0.1 µF.

Two third digits are exceptions for values under 10 pF: 9 means multiply by 0.1 and 8 means multiply by 0.01, so 229 is 2.2 pF and 508 is 0.5 pF. A letter after the digits gives the tolerance: B ±0.10 pF, C ±0.25 pF and D ±0.5 pF are fixed amounts, while F ±1%, G ±2%, J ±5%, K ±10% and M ±20% are percentages of the marked value. The lowest and highest values are the marked value minus and plus that amount.

To find a code, the capacitance is converted to picofarads and written as two significant digits times a power of ten. A value with three significant digits, such as 4.75 nF, has no exact three-digit code.

Formula

C (pF) = (10 × d1 + d2) × 10^n
n = third digit for 0–7;  9 → n = −1;  8 → n = −2
1 nF = 1,000 pF;  1 µF = 1,000,000 pF
deviation = C × t ÷ 100       (t: F 1, G 2, J 5, K 10, M 20)
deviation = 0.10, 0.25, 0.5 pF (B, C, D)
lowest  = C − deviation (not below 0);  highest = C + deviation

Example

104K: 10 × 10^4 = 100,000 pF = 100 nF = 0.1 µF. K is ±10%, so the capacitance may be anywhere from 90 nF to 110 nF.

229: 22 × 10^-1 = 2.2 pF, with no tolerance letter. As 229C it is 2.2 pF ±0.25 pF, from 1.95 pF to 2.45 pF.

In the other direction, 4.7 nF is 4,700 pF = 47 × 10^2, code 472; with a J tolerance it is 472J.

Assumptions and limitations

• The three-digit rule and the 8 and 9 exceptions follow KEMET's multilayer ceramic capacitor data sheets (C1002_X7R, 2026-09-01; C1003_C0G, 2025-02-20), whose part numbers use the same capacitance code.
• KEMET uses a third digit of 8 only for 0.5 to 0.99 pF. Codes 108 to 498 (0.10 to 0.49 pF) apply the same arithmetic below that range and are an extension, not a published use. A code whose first digit is 0 reads by the same rule, so 019 is 0.1 pF, the same value as 108.
• Tolerance letters are decoded as listed in KEMET's C1003_C0G ordering information (2025-02-20): B ±0.10 pF, C ±0.25 pF, D ±0.5 pF, F ±1%, G ±2%, J ±5%, K ±10%, M ±20%. Other letters are not decoded. Where an absolute tolerance exceeds the marked value, the lowest value shown is 0.
• Only three-digit codes are read. Markings in other forms, such as a value printed with its unit or a color code, are not.
• The range covers the marked tolerance only. Changes in capacitance with temperature, applied voltage and age are given in the data sheet for the specific part and are not included.
• The result is a decoding of the marking, not a substitute for the manufacturer's data sheet.

Frequently asked questions