How to Read a Resistor Colour Code: A Practical Guide for South African Electronics Enthusiasts

Resistor Colour Codes Are Simpler Than They Look

Pick up any through-hole resistor and you will see coloured bands printed around its body. Those bands are not decoration—they are the resistor’s datasheet printed directly on the part. Once you learn to read them, you can identify any standard resistor in under five seconds without reaching for a multimeter.

This guide covers the resistor colour code system used by every manufacturer since the 1920s. It applies to carbon-film, metal-film, and wirewound resistors and works for every value from 0.1 Ω to hundreds of megaohms.

The Three Coding Systems

Resistors come in three band configurations:

4-band: two significant digits, one multiplier, one tolerance. Example: brown-black-red-gold.

5-band: three significant digits, one multiplier, one tolerance. Used for 1% precision resistors. Example: brown-black-black-red-brown.

6-band: same as 5-band plus a temperature coefficient band.

The Colour Code Table

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

Multiplier: Black=×1, Brown=×10, Red=×100, Orange=×1,000, Yellow=×10,000, Green=×100,000, Blue=×1,000,000, Gold=×0.1, Silver=×0.01.

Tolerance: Brown=±1%, Red=±2%, Green=±0.5%, Blue=±0.25%, Violet=±0.1%, Gold=±5%, Silver=±10%, No band=±20%.

4-Band Resistor Example

Take brown-black-red-gold: Band 1 (brown)=1, Band 2 (black)=0, Band 3 (red)=×100. Resistance = 10 × 100 = 1,000 Ω = 1 kΩ. Gold = ±5% tolerance. Range: 950Ω to 1,050Ω.

5-Band Resistor Example

Take brown-black-black-red-brown: Bands 1-3 = 100, Band 4 (red)=×100. Resistance = 100 × 100 = 10,000 Ω = 10 kΩ. Brown = ±1%. Range: 9.9 kΩ to 10.1 kΩ.

Common Values

10Ω: brown-black-black-gold, 100Ω: brown-black-brown-gold, 220Ω: red-red-brown-gold, 330Ω: orange-orange-brown-gold, 470Ω: yellow-violet-brown-gold, 1kΩ: brown-black-red-gold, 4.7kΩ: yellow-violet-red-gold, 10kΩ: brown-black-orange-gold, 100kΩ: brown-black-yellow-gold, 1MΩ: brown-black-green-gold.

TRX Electronics, based in Pretoria, stocks resistor kits in through-hole and SMD formats across the E12, E24, and E96 series. Contact us at +27 (0)12 997-0504 or visit trxe.com.

Frequently Asked Questions

Which end do I read from?

Read from the end where bands are clustered. The tolerance band has a visible gap. If gold or silver is last, that’s the tolerance band.

What if colours are hard to read?

Use a multimeter in resistance mode (Ω). It’s unambiguous and faster than decoding faded bands.

How do SMD resistor codes work?

Three- or four-digit code: 472 = 47 × 10² = 4,700 Ω (4.7 kΩ). 1001 = 100 × 10¹ = 1,000 Ω (1 kΩ).

4-band vs 5-band?

5-band provides an extra significant digit for tighter tolerance. Use 5-band (1%) for measurement circuits, 4-band (5%) for pull-ups and general work.