Capacitor Code Calculator

A capacitor code is a short marking printed on small capacitors, such as ceramic disc, film and SMD types, that are too small to carry the full value. The most common system is the 3-digit code. The first two digits are the value and the third digit is a multiplier, which gives the capacitance in picofarads (pF).

A letter after the digits usually shows the tolerance, and a letter and number pair such as 1H or 2A can show the voltage rating.

Take the first two digits as a number, then multiply it by 10 raised to the power of the third digit. The answer is in picofarads.

For example, 104 means 10 × 10⁴ = 100,000 pF = 100 nF = 0.1 µF. In the same way, 473 is 47 × 10³ = 47,000 pF = 47 nF, and 221 is 22 × 10¹ = 220 pF.

Normally the third digit tells you how many zeros to add. The digits 8 and 9 are special cases: 8 means multiply by 0.01 and 9 means multiply by 0.1. They are used for very small values.

So 229 is 22 × 0.1 = 2.2 pF and 689 is 68 × 0.1 = 6.8 pF. The calculator decodes both automatically.

The letter is the tolerance, which tells you how far the real capacitance may be from the marked value. J is ±5%, K is ±10%, M is ±20%, F is ±1%, G is ±2% and Z is +80% / −20%.

The letters B, C and D are used on very small capacitors and are given in picofarads (±0.1, ±0.25 and ±0.5 pF). So 104K is a 100 nF capacitor with ±10% tolerance, which means its real value can be anywhere from 90 nF to 110 nF.

1 µF = 1,000 nF = 1,000,000 pF. To go from pF to nF, divide by 1,000. To go from nF to µF, divide by 1,000 again.

For example, 100,000 pF ÷ 1,000 = 100 nF, and 100 nF ÷ 1,000 = 0.1 µF. The calculator shows all three units at once, so you do not need to do this by hand.

A 104 capacitor is 100 nF (0.1 µF). It is probably the most common value in hobby electronics. It is used as a decoupling or bypass capacitor, placed close to the power pins of ICs and microcontrollers to filter noise on the supply line.

Two other values you will see all the time are 103 (10 nF) and 105 (1 µF).

A 4-digit code works like a 3-digit code, but the first three digits are the value and the fourth digit is the multiplier. For example, 1052 is 105 × 10² = 10,500 pF.

Letter notations put the unit letter where the decimal point would be. 4n7 is 4.7 nF, 2u2 is 2.2 µF and 4p7 is 4.7 pF. In 4R7, the R stands for the decimal point, so it is 4.7 pF, and R47 means 0.47 pF. All of these formats work in the calculator.

Some capacitors, especially SMD and film types, carry a two-character voltage code. Common ones are 1E = 25 V, 1H = 50 V, 2A = 100 V, 2D = 200 V, 2E = 250 V and 2J = 630 V.

These codes are not fully standard between manufacturers, so treat them as a guide and confirm with the datasheet when it matters. Many through-hole ceramic discs simply print the voltage, for example 50V or 100V.

Some manufacturers print the value directly instead of using a code. A plain number such as 0.1 or .1 usually means microfarads (0.1 µF), 100n means 100 nF and 10p means 10 pF.

If you want the matching 3-digit code for any of these, use the Value to Code tab.

Usually not. Aluminium electrolytic capacitors have their capacitance printed directly, such as 470µF 25V, with a stripe or minus sign marking the negative lead. SMD tantalum capacitors often use the same pF-based 3-digit code (106 means 10 µF and 107 means 100 µF) with a voltage letter and a polarity bar.

Always check polarity on these types. Fitting an electrolytic or tantalum capacitor the wrong way round can damage it or the circuit.

Match the capacitance as closely as you can, use the same or a higher voltage rating, and use the same or a tighter tolerance. A higher voltage rating is always safe, a lower one is not.

In timing, filter and oscillator circuits, also keep the same dielectric type (see the next question), because the real value can drift with temperature and applied voltage in ways that change how the circuit behaves.

They describe how stable a ceramic capacitor is over temperature. C0G (also called NP0) is very stable and is the best choice for timing, RF and precision filters. X7R holds its value within about ±15% from −55°C to +125°C and is the usual choice for decoupling. Y5V and Z5U can lose a large part of their capacitance with temperature and DC voltage, so they suit only non-critical uses.

This dielectric code is separate from the value code.

There are three common reasons. The first is tolerance: a K capacitor can be 10% off. The second is measurement conditions, because test frequency, test voltage and lead length all change the reading. The third is the dielectric: X5R, X7R and especially Y5V ceramics lose capacitance under DC bias and as they age.

If a capacitor reads far outside its tolerance range, it may be damaged or marked incorrectly.

Use a multimeter with a capacitance range or an LCR meter. Take the capacitor out of the circuit, or at least lift one lead, and discharge it first, especially larger or high-voltage types.

Very small values, below about 10 pF, are hard to read accurately on basic meters because the probe leads add stray capacitance of their own.

Yes, for marked parts. SMD ceramic capacitors (MLCC) are usually not marked at all, so the value is only on the reel or bag label and cannot be read from the part. Marked SMD parts such as tantalum, film and some ceramic types use the same codes, and the calculator decodes them.

For an unmarked SMD capacitor, measure it with an LCR meter.