Capacitor Colour Code Calculator & How to Read It

This calculator converts the colour bands on a cylindrical ceramic or film capacitor into its capacitance value in picofarads (pF), nanofarads (nF), or microfarads (µF), along with its tolerance and voltage rating where applicable. You enter the colours of the first three bands (and optionally the tolerance and voltage bands), and the calculator returns the capacitance in standard units, the tolerance as a percentage, and the maximum working voltage. The same colour code system is used on many small capacitors, so this tool works for most common components you will encounter in hobby electronics.

Formula

The colour code on a capacitor works exactly like the resistor colour code, but the unit is picofarads (pF). The first two bands give the first two digits of the capacitance value, and the third band is a multiplier (a power of ten). The formula is:

C (pF) = (digit1 × 10 + digit2) × 10^multiplier

Where:

• digit1 = value of the first colour band (e.g., brown = 1)
• digit2 = value of the second colour band (e.g., black = 0)
• multiplier = value of the third colour band (e.g., red = 2, so 10² = 100)
• C = capacitance in picofarads (pF). To convert: 1 nF = 1000 pF, 1 µF = 1,000,000 pF.

The tolerance band (if present) follows the same colour-to-percentage mapping as resistors: brown = ±1%, red = ±2%, gold = ±5%, silver = ±10%. Some capacitors also have a voltage rating band, but that is less standardized and often printed as text.

Worked Example

Using the default values from the calculator: first band = brown (1), second band = black (0), third band = red (2), tolerance = gold (±5%).

1. First two digits: 1 and 0, so the base number is 10.
2. Multiplier: red = 2, meaning 10² = 100.
3. Multiply: 10 × 100 = 1000 pF.
4. Convert to nF: 1000 pF ÷ 1000 = 1 nF.
5. Convert to µF: 1000 pF ÷ 1,000,000 = 0.001 µF.
6. Tolerance: gold = ±5%, so the actual capacitance is between 950 pF and 1050 pF.

The calculator shows 1000 pF, 0.001000 µF, and 5% tolerance, matching the manual calculation.

When to Use the Colour Code

Colour coding appears on small ceramic disc capacitors, some film capacitors, and older electrolytic capacitors (though those usually have the value printed). You will need this calculator when the capacitor is too small to print numbers on, or when the printing has worn off. The same code is used on resistors, so if you already know resistor colour codes, you can read capacitor codes with one extra step: the result is always in picofarads, not ohms.

Note that not all capacitors use this system. Many modern capacitors have the value printed directly as a number (e.g., “104� means 10 × 10� pF = 100 nF). The colour code is most common on components made before the 1990s and on some cheap ceramic capacitors still made today.

How to Read the Bands

Capacitors have either 3, 4, or 5 colour bands. The orientation matters: the bands are read from the top or from the side with the lead closest to the first band. If there is a gap, the bands are read from the end with the smaller gap.

• 3 bands: first two digits + multiplier, no tolerance (default ±20%).
• 4 bands: first two digits + multiplier + tolerance.
• 5 bands: first three digits + multiplier + tolerance (used for high-precision capacitors). The third band is a digit, not a multiplier.

For a 5-band capacitor, the formula becomes: C = (d1×100 + d2×10 + d3) × 10^multiplier pF. This calculator handles 3- and 4-band types; for 5-band, you can combine the first three digits manually and then use the multiplier.

Common Mistakes and Tips

• Unit mix-ups: The result is always in pF first. Beginners often read “1000� and think it is 1000 µF, but it is 1000 pF = 1 nF. Always convert to a convenient unit.
• Reading direction: If you read the bands backwards, you will get a wildly wrong value. Look for the tolerance band (gold or silver) – it is usually at the end and wider.
• Colour confusion: Brown vs. red, and blue vs. grey, are easy to mix up under poor lighting. Use a bright light or magnifying glass.
• Voltage rating: The colour code does not give the voltage rating. That is usually printed on the body as a number (e.g., “50V�). If it is missing, assume a low voltage (under 50V) for small ceramics.
• Not all capacitors follow this: Some use a different system (e.g., EIA-198 for ceramic, or a direct numeric code). When in doubt, measure with an LCR meter.

Limits of the Colour Code

The colour code only works for capacitors that actually use it. Many modern capacitors, especially surface-mount (SMD) types, use a numeric code or no marking at all. Also, the code does not tell you the dielectric type (e.g., ceramic, polyester, mica), which affects temperature stability and loss. For critical circuits, always check the datasheet or measure the capacitance with a meter.

Another limit: the colour code gives the nominal value, but the actual capacitance can vary by the tolerance (e.g., ±10%). For timing circuits, that variation can be significant. Use a capacitor with a tighter tolerance (e.g., ±2% or ±5%) when precision matters.

Frequently Asked Questions

What do the colours mean on a capacitor?

Each colour represents a number from 0 to 9, following the same chart as resistors: black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, violet=7, grey=8, white=9. The first two or three bands are digits, the next band is a multiplier (power of ten), and the last band (if present) is tolerance.

How do I convert pF to nF or µF?

Divide by 1000 to go from pF to nF (1000 pF = 1 nF). Divide by 1,000,000 to go from pF to µF (1,000,000 pF = 1 µF). For example, 4700 pF = 4.7 nF = 0.0047 µF.

What does a capacitor marked “104� mean?

That is a numeric code, not a colour code. The first two digits are 10, and the third digit is the multiplier: 10 × 10� = 100,000 pF = 100 nF = 0.1 µF. This is common on ceramic capacitors.

Can I use this calculator for electrolytic capacitors?

No. Electrolytic capacitors almost always have the value printed directly (e.g., “10 µF�, “47 µF�) along with the voltage rating. They rarely use colour bands.

Why does my capacitor have 5 bands?

A 5-band capacitor uses the first three bands as digits, the fourth as a multiplier, and the fifth as tolerance. It gives higher precision. For example, brown-black-orange-red-gold would be 10,000 pF (10 nF) with ±5% tolerance.

What is the voltage rating on a colour-coded capacitor?

The colour code does not include voltage. The voltage rating is usually printed as text (e.g., “50V�, “100V�). If you cannot find it, assume a low voltage (under 50V) for small ceramic capacitors, and never exceed it in a circuit.

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in b1 | 1st band colour | - | brown | 0
in b2 | 2nd band colour | - | black | 0
in b3 | 3rd band colour | - | red | 0
sel tol | Tolerance band | Brown=1, Red=2, Gold=3, Silver=4 | 3
out cap_pf | Capacitance | pF | (b1*10 + b2) * 10^b3 | 0
out cap_uf | Capacitance | µF | ((b1*10 + b2) * 10^b3) / 1000000 | 6
out tol_pct | Tolerance | % | (tol==1?5:(tol==2?2:(tol==3?10:20))) | 0