Use this Resistor Colour Code Calculator to determine the resistance value and tolerance of standard 4-band and 5-band resistors. You can work in either direction: select the resistor colour bands to calculate the resistance value, or enter a known resistance value to find the corresponding colour code.The calculator supports common resistor colour codes, including resistance, multiplier, and tolerance bands, making it useful for identifying unknown resistors, checking component values, and selecting the correct colour bands when designing circuits.
Results
- Resistance
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- Tolerance
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- Minimum resistance
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- Maximum resistance
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Results
- Colour bands
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- Resistance
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- Minimum resistance
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- Maximum resistance
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How to read resistor colour codes
Hold the resistor so the tolerance band (often gold or silver, and usually slightly separated from the others) is on the right. Read the bands from left to right.
- 4-band: two digit bands, one multiplier band and one tolerance band.
- 5-band: three digit bands, one multiplier band and one tolerance band. Used for precision resistors (typically ±1 % or better).
Formula
R = (digits) × multiplier
Rmin = R × (1 − tolerance), Rmax = R × (1 + tolerance)
Example: Brown, Black, Red, Gold = 1, 0 × 100 = 1,000 Ω = 1 kΩ ±5 %.
Notes
- Colours can be hard to tell apart (e.g. red/orange, brown/red, violet/grey). If in doubt, confirm the value with a multimeter.
- Some resistors have a sixth band showing the temperature coefficient; it does not change the resistance value.
