Resistor Color Code Calculator4 · 5 · 6 band decoder
A resistor’s colour bands encode its value: the first two or three bands are digits, the next is a power-of-ten multiplier, and the last gives the tolerance. Brown–black–red–gold is 10 × 100 = 1 kΩ ±5%. Pick the colours of a 4, 5 or 6 band resistor to read its resistance and range, or type a resistance to get the bands. The resistor drawing updates as you choose.
Formula verified against IEC 60062 — Marking codes for resistors and capacitors · Wikipedia — Electronic color code
By Manzoor Ahmad · Pharmacist & calculator developerReviewed & updated
Pick the bands
Read from the end opposite the gold or silver tolerance band. The wider gap sits before the tolerance band.
Step-by-step working
What is resistor color code?
The resistor colour code is a system of coloured bands printed around a resistor’s body to show its resistance, tolerance and sometimes its temperature coefficient. Each colour stands for a digit from 0 to 9, a multiplier or a tolerance.
It dates from the 1920s and is standardised internationally as IEC 60062. Once you know ten colours, you can read any through-hole resistor without a meter.
Quick answers
What are the colour bands for a 10k resistor?
Brown–black–orange–gold on a 4-band resistor (10 × 1,000 = 10 kΩ ±5%). On a 5-band: brown–black–black–red–brown (100 × 100, ±1%).
What colour is a 220 ohm resistor?
Red–red–brown–gold: 22 × 10 = 220 Ω ±5%. As a 5-band: red–red–black–black–brown.
How do I know which end to start reading?
Start at the end with the band closest to the edge. The tolerance band (often gold or silver) usually has a wider gap before it and sits on the right.
What is the difference between 4, 5 and 6 band resistors?
4-band has two digits; 5-band has three digits for precision (usually ±1% or better); 6-band adds a temperature coefficient band. Decoded values feed straight into the Ohm’s law calculator.
How the resistor colour code works
Colour code standard: IEC 60062. Mnemonic for digits 0–9: “Big Brown Rabbits Often Yield Great Big Vocal Groans When Gingerly Slapped” (adds gold and silver).
| Symbol | Meaning | SI unit |
|---|---|---|
| d₁ d₂ d₃ | Significant digit bands | 0–9 |
| 10ⁿ | Multiplier band (gold = 0.1, silver = 0.01) | — |
| Tol. | Tolerance band | % |
| TC | Temperature coefficient (6-band only) | ppm/K |
How to read a resistor colour code
- Orient the resistor so the gold or silver tolerance band is on the right.
- Read the digit bands from left to right (two on 4-band, three on 5- and 6-band).
- Multiply by the multiplier band’s power of ten.
- Apply the tolerance to get the allowed range.
Worked example: yellow–violet–black–brown–brown
A 5-band resistor reads yellow (4), violet (7), black (0), brown (×10), brown (±1%).
R = 470 × 10 = 4,700 Ω = 4.7 kΩ
Range at ±1%: 4.653 kΩ to 4.747 kΩ
The 4-band version of the same value is yellow–violet–red–gold: 47 × 100 = 4.7 kΩ ±5%.
Resistor colour code chart
All bands at a glance.
| Colour | Digit | Multiplier | Tolerance | Temp. coeff. |
|---|---|---|---|---|
| Black | 0 | ×1 | — | 250 ppm/K |
| Brown | 1 | ×10 | ±1% | 100 ppm/K |
| Red | 2 | ×100 | ±2% | 50 ppm/K |
| Orange | 3 | ×1k | — | 15 ppm/K |
| Yellow | 4 | ×10k | — | 25 ppm/K |
| Green | 5 | ×100k | ±0.5% | 20 ppm/K |
| Blue | 6 | ×1M | ±0.25% | 10 ppm/K |
| Violet | 7 | ×10M | ±0.1% | 5 ppm/K |
| Grey | 8 | ×100M | ±0.05% | 1 ppm/K |
| White | 9 | ×1G | — | — |
| Gold | — | ×0.1 | ±5% | — |
| Silver | — | ×0.01 | ±10% | — |
Common mistakes to avoid
- Reading from the wrong end. If you read gold first, flip it: gold is never a first digit.
- Mixing red and orange, or brown and red, under poor light. Confirm with a multimeter when it matters.
- Treating 5-band resistors like 4-band. The third band is a digit, not the multiplier.
Manzoor Ahmad
Pharmacist turned Web Developer & Calculator Engineer · 13+ years in web developmentI’m a pharmacist by training who turned into a full-time tech geek, and for 13+ years I’ve designed and coded web tools. My pharmacy degree included physical pharmacy and pharmaceutics — states of matter, heat, flow and reaction kinetics — so the physics behind these tools is familiar ground, not a new hobby.
I’m not a physicist, so I don’t ask you to take my word for it: every formula on this page is traced to an open university textbook or NIST reference data, and the calculator is tested against published worked examples before it goes live. Spot an error? Tell me and it will be fixed and dated on the next update.
Resistor Color Code Calculator: frequently asked questions
Bands 1 and 2 are digits, band 3 is the power-of-ten multiplier and band 4 is the tolerance. Brown–black–red–gold = 10 × 100 = 1 kΩ ±5%.
As a tolerance band, gold means ±5%. As a multiplier, it means × 0.1, used for values under 10 Ω.
Brown–black–red (4-band), usually with a gold tolerance band: 1 kΩ ±5%.
Small cylindrical resistors have no room for printed text, and colour bands can be read from any angle. The scheme is standardised in IEC 60062.
A series of 12 preferred values per decade (1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2), designed so that ±10% tolerance bands overlap.
References & sources
- IEC 60062 — Marking codes for resistors and capacitors — the colour code standard
- Wikipedia — Electronic color code — band chart and history
- OpenStax — University Physics, Volume 2 — Ch. 9.3, resistance
Disclaimer: This calculator is an educational tool built on idealised textbook models. It is not a substitute for professional engineering or safety calculations.