Resistor Color Code Calculator

The resistor colour code chart

The full IEC 60062 code. It is generated from the same tables the calculator above decodes with, so the two cannot drift apart.

Gold and silver mean 0.1 and 0.01 in the multiplier position, and ±5% and ±10% in the last band. The same colour means different things depending on where it sits.

Four-band colours for the values you look up most

The swatches are a guide. Real parts look different under different light and against different body colours, which is why the calculator also tells you whether the value you read is one that is actually manufactured.

Reading a resistor colour code from the bands you can see

Start from the end where the bands are bunched together, read the colours in order, and find that sequence below. A gold fourth band means ±5%. These are the sixteen values a parts drawer actually holds; for anything else, type the colours into the calculator above.

• Brown Black Black Gold10Ω ±5% 10R
• Red Red Black Gold22Ω ±5% 22R
• Yellow Violet Black Gold47Ω ±5% 47R
• Brown Black Brown Gold100Ω ±5% 100R
• Red Red Brown Gold220Ω ±5% 220R
• Orange Orange Brown Gold330Ω ±5% 330R
• Yellow Violet Brown Gold470Ω ±5% 470R
• Brown Black Red Gold1kΩ ±5% 1K
• Red Red Red Gold2.2kΩ ±5% 2K2
• Yellow Violet Red Gold4.7kΩ ±5% 4K7
• Brown Black Orange Gold10kΩ ±5% 10K
• Red Red Orange Gold22kΩ ±5% 22K
• Yellow Violet Orange Gold47kΩ ±5% 47K
• Brown Black Yellow Gold100kΩ ±5% 100K
• Red Red Yellow Gold220kΩ ±5% 220K
• Brown Black Green Gold1MΩ ±5% 1M

With five bands the first three are digits and the fourth is the multiplier, so the sequences above do not apply — the calculator handles 4, 5 and 6 bands, reports what the same bands mean read from the other end, and says whether either value is one that is actually manufactured.

The standard resistor values

Resistors are not made in arbitrary values. Each series fixes the values in one decade, and real parts are those numbers times a power of ten — so E24 holding 4.3 and 4.7 means 430 Ω, 4.3 kΩ and 43 kΩ are all stock items and 4.5 kΩ is not one at any tolerance you can buy at ±5%. If a value you read off the bands is missing from this list, the odds are you misread a band.

E48, E96 and E192 are the ±2%, ±1% and ±0.5% series. They are much finer and need three significant digits, which is why precision parts carry five bands rather than four. The calculator above can work in any of them.

Which end do you read from

The bands are read left to right, but a resistor has no printed arrow. The convention that tells you which way round to hold it is spacing: the tolerance band sits slightly apart from the group, at the end you read last. Gold and silver help too — neither is a digit, so a part with gold at one end is read from the other.

Some codes are valid either way. Brown-black-orange-red is 10 kΩ ±2%; the same bands reversed, red-orange-black-brown, are 23 Ω ±1%. Both are real resistors. The tool reports the reverse reading whenever it is a valid code, and says whether that value is one that is actually manufactured, which usually settles it.

Four bands or five

Four-band resistors carry two significant digits; five-band ones carry three, and are how ±1% and tighter parts are marked, because E96 values such as 4.75 kΩ need the third digit. Reading a five-band part as a four-band one shifts the multiplier by a band and produces a value ten times wrong. Count the bands before decoding, and expect a brown, red or green tolerance band on a five-band part where a four-band one would have gold or silver.

The value should exist

This is the check that catches misreads. Resistors are made only in the preferred values of IEC 60063: ±5% parts in E24 (24 values per decade — 4.3, 4.7, 5.1, and so on), ±1% parts in E96. A ±5% resistor that decodes to 4.5 kΩ does not exist; one of its digit bands has been misread and it is really 4.3k or 4.7k. The tool looks the decoded value up in the series its tolerance implies and, when it is missing, names the neighbours that are made.

The reverse holds when writing a code for a value: the bands for 4.5 kΩ ±5% are perfectly well defined, but no such part exists to buy. The voltage divider and LED resistor calculators work from the same tables, so a value they suggest will always have a valid, purchasable code here.

Colours that lie

Brown, red and orange are hard to tell apart on a small part under warm light, and old resistors fade — a red band can look orange, a violet one blue. When the decoded value is not a standard one, that is the first thing to suspect; when it is standard but the circuit misbehaves, a meter settles it in seconds. Bands are a label, not a measurement, and a resistor that has been hot can drift outside its tolerance without the colours changing at all.

Gold and silver as multipliers

Below 10 Ω the multiplier goes fractional: gold is ×0.1 and silver is ×0.01. Red-red-gold-gold is 2.2 Ω ±5%, and yellow-violet-silver-gold is 0.47 Ω. These low values turn up as current-sense shunts and in power supplies, and they are the case where reading from the wrong end is easiest, since both ends can look like a gold band.

The code on a schematic

Drawings and parts lists rarely write 4.7 kΩ. They write 4K7: the multiplier letter stands in for the decimal point, so 1M5 is 1.5 MΩ, 10R is 10 Ω, and R22 is 0.22 Ω. The reason is mundane — a decimal point vanishes on a photocopy or a low-resolution screen, and 47K read as 4.7K is a bug that ships. The tool shows this form next to every value.

Surface-mount parts are marked differently

Chip resistors have no room for bands. Small ones carry a three- or four-digit code where the last digit is the number of zeros — 472 is 4.7 kΩ, 1002 is 10 kΩ — and precision parts use the EIA-96 scheme of two digits and a letter. The smallest packages carry nothing at all, and the value lives only on the reel label and the BOM.