Electrical · passive components

Resistor Colour Code Calculator

4-band decode and encode — same IEC colours as the circuit tool.

Mode

Value

Colour table

SMD code

Three digits (473), four digits (4702), an R for the decimal point (4R7), or an EIA-96 code (01C).

Availability

Can you actually buy this value?

Plain ohms, or 4k7, 2.2M, 470R.

Power

Will it survive?

Field notes

Why there is a 4.7 kΩ resistor but no 5 kΩ

How it works

4-band resistors

Digit, digit, multiplier, tolerance — the standard 4-band code (IEC 60062). Two significant figures and a power of ten is all the code can express, which is why the values you can actually buy are the ones they are. The same band rendering lives inside Electrical Circuit when you solve for resistance.

Worked example

Yellow, violet, red, gold. Yellow is 4, violet is 7, red multiplies by 100: 47 × 100 = 4.7 kΩ. Gold is the tolerance band at ±5%.

So the part in your hand is guaranteed to be somewhere between 4,465 Ω and 4,935 Ω — a spread of nearly 500 Ω. If your design genuinely needs 4.7 kΩ rather than "about 4.7 kΩ", the colour code is not the thing to rely on; measure it.

How do I read left to right?

The tolerance band (gold/silver) is usually set slightly apart toward one end — start from the other end.

Why “nearest” when encoding?

Not every ohm value maps to exact 2-digit × 10ⁿ bands. Encode mode rounds to the nearest representable 4-band value.

What this page covers, and what it assumes

4-band IEC 60062 only. It assumes the bands are read from the end furthest from the tolerance band, and that the colours are true — both assumptions fail often enough in practice to be worth checking. Not covered: 5-band and 6-band parts (a third significant digit, and a temperature-coefficient band), the obsolete body-tip-dot scheme, and surface-mount numeric codes. The colour code says nothing at all about power rating — that comes from the physical size of the part.

Reference only. Confirm with a multimeter for critical circuits. 4-, 5- and 6-band codes are all covered; 4-band parts read two significant digits, 5- and 6-band read three.
Version history · 2 releases
  1. v0.962026-07-28Resistor code reads 5- and 6-band parts; concrete gains a wastage allowance. Two tools, not three — see notes
  2. v1.472026-08-03Resistor: E-series availability, SMD codes, two-resistor combinations, power; two new rules

Releases in which this page changed, newest last. Derived from the archived copy of every release, not from notes written afterwards — so it reflects what actually shipped. Site-wide passes are left out; they are in the full changelog.