Resistor Color Code Decoder
Resistance
1.0kΩ
How it works
Resistors are marked with coloured bands that encode their resistance value in ohms and their tolerance. Reading resistor colour codes is a fundamental electronics skill — and essential for working with through-hole components, understanding circuit diagrams, and troubleshooting circuits. The Resistor Colour Code Decoder translates colour bands to ohms (and vice versa) for 3-band, 4-band, 5-band, and 6-band resistors.
**The colour code (digit values)** Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9.
**4-band resistor (most common)** Band 1 (first digit) + Band 2 (second digit) + Band 3 (multiplier) + Band 4 (tolerance). Example: Red-Red-Orange-Gold: 2-2-×1000-±5% = 22,000 Ω = 22 kΩ ±5%.
Multiplier colours: Black=×1; Brown=×10; Red=×100; Orange=×1k; Yellow=×10k; Green=×100k; Blue=×1M; Gold=×0.1; Silver=×0.01.
Tolerance colours: Gold=±5%; Silver=±10%; Brown=±1%; Red=±2%.
**5-band precision resistors** Band 1+2+3 (three digits) + Band 4 (multiplier) + Band 5 (tolerance). Used for precision resistors (±0.5%, ±0.25%, ±0.1%). Example: Red-Red-Black-Red-Brown = 220 × 100 = 22,000 Ω ±1%.
**Mnemonic for the colour sequence** "Better Be Right Or Your Great Big Ventures Go Wrong" (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White). Or "Bad Boys Rape Our Young Girls But Violet Gives Willingly".
Privacy: all decoding runs in the browser. No data is transmitted.
Frequently Asked Questions
- 5-band resistors are precision types (tolerance ≤ 1%). Read: Band 1 (digit 1) + Band 2 (digit 2) + Band 3 (digit 3) + Band 4 (multiplier) + Band 5 (tolerance). Example: Brown-Black-Black-Red-Brown = 1-0-0-×100-±1% = 10,000Ω = 10 kΩ ±1%. 6-band resistors add a temperature coefficient band (Band 6): Brown = 100 ppm/°C, Red = 50 ppm/°C, Orange = 15 ppm/°C, Yellow = 25 ppm/°C, Blue = 10 ppm/°C, Violet = 5 ppm/°C.
- Read from the end with the band closest to the edge. If ambiguous: the tolerance band (gold or silver) is always last — so start from the opposite end. Gold and silver bands represent tolerances (±5% and ±10%) and multipliers (×0.1 and ×0.01). If a gold or silver band is at one end, that end is the LAST band, so start from the other end. If both ends have bands equally close to the edge: find the gold or silver band and work backwards. A gap between the last two bands is a common manufacturing aid — start from the end with the closer-spaced bands.
- For a red LED (forward voltage Vf ≈ 2.0V) from a 5V supply at 20mA: R = (5 − 2) / 0.02 = 150Ω. Nearest standard value: 150Ω (E12 series). For a white or blue LED (Vf ≈ 3.3V) from 5V at 20mA: R = (5 − 3.3) / 0.02 = 85Ω → use 82Ω (E12 nearest) or 100Ω for a slightly more conservative 17mA. From 3.3V supply with blue LED: R = (3.3 − 3.3) / 0.02 = 0Ω — the forward voltage equals supply voltage! Don't connect a blue LED directly to 3.3V; use 5V supply or limit current with a small resistor (33Ω for ~15mA).
- Resistors are manufactured in preferred value series: E12 (12 values per decade, ±10% tolerance): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 (and ×10 multiples). E24 (24 values, ±5%): adds 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91. E96 (96 values, ±1%): precision series. The series are designed so that any value within the tolerance range is covered by the nearest standard value. If you need 150Ω, it's in E12 (150 = 15 × 10). If you need 237Ω, the nearest E24 value is 240Ω.