Resistor Color Code Calculator
Through-hole resistors carry their value in coloured bands. Once the code is in your head you can read any part at a glance. Until then — use this.
It works in both directions: click a band to change it and watch the value update, or type the value you want and watch the bands rearrange to match.
Reading a resistor
Section titled “Reading a resistor”Most parts you meet are 4-band. Precision parts use 5.
4-band
Section titled “4-band”| Band | Meaning |
|---|---|
| 1 | First significant digit |
| 2 | Second significant digit |
| 3 | Multiplier (×10ⁿ) |
| 4 | Tolerance |
Value = (Band1 × 10 + Band2) × Multiplier
Yellow, violet, red, gold → (4, 7) × 100 → 4.7 kΩ ±5%
5-band
Section titled “5-band”| Band | Meaning |
|---|---|
| 1 | First significant digit |
| 2 | Second significant digit |
| 3 | Third significant digit |
| 4 | Multiplier |
| 5 | Tolerance |
Value = (Band1 × 100 + Band2 × 10 + Band3) × Multiplier
Which end is band 1?
Section titled “Which end is band 1?”- The tolerance band sits alone at one end, with a noticeably wider gap before it. Start from the opposite end and read toward the gap.
- Gold and silver are never digits. If you can see one, that end is the finish.
- Band 1 is usually closer to its lead than the tolerance band is to its own.
The full colour code
Section titled “The full colour code”| Colour | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | ×1 | — |
| Brown | 1 | ×10 | ±1% |
| Red | 2 | ×100 | ±2% |
| Orange | 3 | ×1 k | — |
| Yellow | 4 | ×10 k | — |
| Green | 5 | ×100 k | ±0.5% |
| Blue | 6 | ×1 M | ±0.25% |
| Violet | 7 | ×10 M | ±0.1% |
| Grey | 8 | ×100 M | ±0.05% |
| White | 9 | ×1 G | — |
| Gold | — | ×0.1 | ±5% |
| Silver | — | ×0.01 | ±10% |
Values worth knowing by sight
Section titled “Values worth knowing by sight”| Value | 4-band code | What it is usually doing |
|---|---|---|
| 10 Ω | Brown, black, black, gold | Current limiting at high current |
| 100 Ω | Brown, black, brown, gold | LED limiting |
| 330 Ω | Orange, orange, brown, gold | LED on a 3.3 V rail |
| 470 Ω | Yellow, violet, brown, gold | General LED limiting |
| 1 kΩ | Brown, black, red, gold | Pull-up or pull-down |
| 4.7 kΩ | Yellow, violet, red, gold | I²C pull-up |
| 10 kΩ | Brown, black, orange, gold | GPIO pull-up or pull-down |
| 100 kΩ | Brown, black, yellow, gold | High-impedance pull-up |
Tolerance in practice
Section titled “Tolerance in practice”- ±1% (brown) — metal film, for precision work
- ±2% (red) — metal film
- ±5% (gold) — carbon film, and what you almost always have in the drawer
- ±10% (silver) — carbon composition, older stock
For pull-ups, LED limiting and voltage dividers on a microcontroller, ±5% is fine. The tool shows the real spread a tolerance implies — a 4.7 kΩ ±5% part is anywhere from 4.46 kΩ to 4.93 kΩ, and that is normal.