Resistor Color Codes Explained — Read Any Resistor in Seconds

You pull a resistor out of a bin and see four colored bands: brown, black, orange, gold. Is that 10 kΩ or 100 kΩ? If you've ever stalled on this, you're not alone. The color code system is simple once you learn the pattern — but having a resistor color code decoder open while you're building saves a lot of squinting.

How the color code works

Every through-hole resistor uses colored bands to encode its value. The system is the same worldwide, defined by IEC 60062.

The 10 colors

Color	Digit	Multiplier	Tolerance
Black	0	×1	—
Brown	1	×10	±1%
Red	2	×100	±2%
Orange	3	×1k	±0.05%
Yellow	4	×10k	±0.02%
Green	5	×100k	±0.5%
Blue	6	×1M	±0.25%
Violet	7	×10M	±0.1%
Grey	8	×100M	±0.01%
White	9	×1G	—
Gold	—	×0.1	±5%
Silver	—	×0.01	±10%

4-band resistors

The most common type. The bands encode:

1. First digit — tens place
2. Second digit — ones place
3. Multiplier — power of ten
4. Tolerance — accuracy (gold = 5%, silver = 10%)

Example: Brown–Black–Orange–Gold = 1, 0, ×1000 = 10,000 Ω (10 kΩ) ±5%

5-band resistors

Higher precision resistors add a third significant digit:

1. First digit
2. Second digit
3. Third digit
4. Multiplier
5. Tolerance

Example: Brown–Red–Black–Brown–Brown = 1, 2, 0, ×10 = 1,200 Ω (1.2 kΩ) ±1%

Which end do you read from?

This trips up beginners constantly. Two rules:

1. The tolerance band (gold/silver) is always last. Orient the resistor so the gold or silver band is on the right.
2. The first band is closer to one end. If both ends look equidistant, the tolerance band is usually slightly separated from the others.

When in doubt, use a multimeter to verify — or just type the colors into the decoder tool.

Common values you'll see constantly

These are the resistors you'll grab most often:

Bands	Value	Typical use
Brown–Black–Brown–Gold	100 Ω	Current limiting
Brown–Black–Red–Gold	1 kΩ	Pull-up/pull-down
Yellow–Violet–Red–Gold	4.7 kΩ	I2C pull-ups
Brown–Black–Yellow–Gold	100 kΩ	Input bias
Red–Red–Brown–Gold	220 Ω	LED current limiting
Orange–Orange–Brown–Gold	330 Ω	LED current limiting (3.3V)

What about SMD resistors?

Surface-mount resistors don't use color bands. They use a numeric code printed on the component: 3-digit, 4-digit, or EIA-96. A "103" marking means 10 × 10³ = 10 kΩ.

If you're working with SMD parts, the SMD resistor code decoder handles all three formats.

Mnemonics (if you want to memorize)

The classic mnemonic for the digit order (0–9) is:

Black Bears Robbed Our Yellow Gummy Bears Very Greedily Wednesday

Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9.

Or skip the mnemonic entirely and keep the decoder bookmarked. It's faster and doesn't require memory tricks.

When colors are ambiguous

Old or heat-damaged resistors can have faded bands. Brown and red look similar under bad lighting. Orange and yellow can blur together. In these cases:

1. Measure with a multimeter — always the most reliable method
2. Check the schematic — if you know the expected value, you can confirm the bands match
3. Compare with known resistors — line up the unknown next to resistors from the same batch

The color code system has been around since the 1920s. It works, but it was designed for an era when printing on tiny cylindrical components was impractical. Now we have tools that make it instant.