Through-hole resistors are marked with coloured bands instead of printed numbers. The first two or three bands are digits, the next is a power-of-ten multiplier, then the tolerance – and on 6-band resistors a temperature coefficient.
How to use the Resistor Color Code Calculator
- Number of bands
- Band 1 (1st digit)
- Band 2 (2nd digit)
- Band 3 (3rd digit)
- Multiplier band
- Tolerance band
- Temperature coefficient band
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the number of bands and pick the colour of each band from left to right.
Inputs explained
| Field | What to enter |
|---|---|
| Number of bands | Choose one: 4 bands, 5 bands, 6 bands |
| Band 1 (1st digit) | Choose one: Brown (1), Red (2), Orange (3), Yellow (4) … |
| Band 2 (2nd digit) | Choose one: Black (0), Brown (1), Red (2), Orange (3) … |
| Band 3 (3rd digit) | Choose one: Black (0), Brown (1), Red (2), Orange (3) … |
| Multiplier band | Choose one: Black (×1), Brown (×10), Red (×100), Orange (×1k) … |
| Tolerance band | Choose one: Brown (±1%), Red (±2%), Green (±0.5%), Blue (±0.25%) … |
| Temperature coefficient band | Choose one: Black (250 ppm/K), Brown (100 ppm/K), Red (50 ppm/K), Orange (15 ppm/K) … |
What each result means
- Minimum = [Resistance]×(1 – [Tolerance band]÷100)
- Maximum = [Resistance]×(1 + [Tolerance band]÷100)
Formula
4 bands: R = (10·d₁ + d₂) × multiplier · 5–6 bands: R = (100·d₁ + 10·d₂ + d₃) × multiplier
Worked example
Inputs — Number of bands: 4 bands; Band 1 (1st digit): Brown (1); Band 2 (2nd digit): Black (0); Multiplier band: Red (×100); Tolerance band: Gold (±5%).
Results — Resistance = 1,000 Ω; Minimum = 950 Ω; Maximum = 1,050 Ω.
Key terms
- Tolerance
- Allowed deviation from the nominal value.
Frequently asked questions
How do I know which end to start from?
The tolerance band (often gold or silver) is usually set apart on the right.
What does brown-black-red-gold mean?
1, 0, ×100, ±5% = 1 kΩ ± 5%.
Why do 5-band resistors exist?
Precision resistors need three significant digits.
Is there a mnemonic?
"Bad Beer Rots Our Young Guts But Vodka Goes Well" – black to white.