Resistor Color Code Calculator · Practical guide
How to Read a 4 Band Resistor Color Code
Four bands, one simple system: two digits, a multiplier, and a tolerance give you the full resistance value.
At a glance
The Short Answer
Hold the resistor so the tolerance band (usually gold or silver) is on the right, then read the bands left to right: the first band is the first digit, the second band is the second digit, the third band is the multiplier, and the fourth band is the tolerance. For example, brown-black-red-gold decodes as 1, 0, ×100, ±5% — a 1,000 Ω (1 kΩ) resistor.
Interactive tool
Resistor Color Code Calculator
Enter your own values, then compare the result with the examples below.
Resistor Value
What Each Band Means
Every color stands for a number from 0 to 9. Gold and silver are special: as multipliers they mean ×0.1 and ×0.01, and as tolerance they mean ±5% and ±10%.
| Color | Digit | Multiplier |
|---|---|---|
| Black | 0 | ×1 |
| Brown | 1 | ×10 |
| Red | 2 | ×100 |
| Orange | 3 | ×1,000 |
| Yellow | 4 | ×10,000 |
| Green | 5 | ×100,000 |
| Blue | 6 | ×1,000,000 |
| Violet | 7 | ×10,000,000 |
| Gray | 8 | ×100,000,000 |
| White | 9 | ×1,000,000,000 |
| Gold | — | ×0.1 |
| Silver | — | ×0.01 |
A Worked Example
Take the classic brown-black-red-gold resistor. Brown is 1, black is 0, and red as a multiplier is ×100, so the value is (1 × 10 + 0) × 100 = 1,000 Ω or 1 kΩ. Gold as the tolerance band means ±5%, so the actual resistance can fall anywhere between 950 Ω and 1,050 Ω. A red-red-brown-gold resistor, by the same logic, is 22 × 10 = 220 Ω ±5%.
Which End Do You Start From?
The tolerance band is set slightly apart from the others and is usually gold or silver, so put it on the right. If the bands look evenly spaced, remember that a 4-band resistor almost never starts with gold or silver — flip it and read again. The calculator above shows the decoded value, tolerance, and acceptable range as soon as you match the bands.
Frequently Asked Questions
What if my resistor has no tolerance band?
Some older or low-precision resistors omit the fourth band. In that case the tolerance defaults to ±20%. The colored bands are still read the same way for the value itself.
What does the multiplier band actually do?
The multiplier tells you how many zeros to add (or, for gold and silver, how to scale down). Red as a multiplier means ×100, so digit bands of 4 and 7 with a red multiplier give 4,700 Ω.
Can gold or silver appear as digit bands?
No. Gold and silver only appear as multiplier or tolerance bands. If you see gold in the first or second position, you are reading the resistor from the wrong end.
Why does the decoded value differ from my multimeter reading?
That is exactly what tolerance means. A 1 kΩ ±5% resistor can legitimately measure anywhere from 950 Ω to 1,050 Ω and still be within specification.