How to Read Resistor Color Codes (4-Band and 5-Band)

Resistors are usually too small to print a number on legibly, so manufacturers mark them with colored stripes instead — a system standardized decades ago and still used on nearly every leaded resistor sold today. Once you know the color-to-digit mapping, reading a resistor is entirely mechanical, no chart required after a bit of practice.

The digit colors

Ten colors stand for the ten digits, in an order worth memorizing because it also sets the multiplier bands:

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

A common mnemonic runs: Black Beetles Running Over Your Garden Bring Very Great Woe — matching black, brown, red, orange, yellow, green, blue, violet, grey, white in order. Any memory trick that sticks will do.

Reading a 4-band resistor

A standard 4-band resistor has two significant-digit bands, a multiplier band, and a tolerance band. The first two bands give you a two-digit number; the third band tells you how many zeros to add (or, for gold and silver, a fractional multiplier); the fourth band gives the tolerance.

Take brown-black-red-gold. Brown and black give the digits 1 and 0, so the base number is 10. Red as a multiplier means ×100 (10 to the power of 2), so 10 × 100 = 1,000Ω, or 1kΩ. Gold as the tolerance band means ±5%, so the resistor’s true value falls somewhere between 950Ω and 1,050Ω.

Gold and silver appear only in the multiplier and tolerance positions, never as digits. As multipliers, gold means ×0.1 and silver means ×0.01 — used for resistors under 10Ω. As tolerances, gold means ±5% and silver ±10%. If there’s no fourth band at all, the implied tolerance is a loose ±20%.

Reading a 5-band resistor

5-band resistors add a third significant-digit band, giving finer resolution. The pattern becomes three digits, then a multiplier, then tolerance. Brown-black-black-red-brown decodes as digits 1, 0, 0 (giving 100), a red multiplier (×100), for 100 × 100 = 10,000Ω, or 10kΩ, with a brown tolerance band meaning ±1%. The extra digit is why 5-band resistors are the usual choice when a circuit needs 1% or 2% precision rather than the looser 5% or 10% that 4-band parts typically offer.

Which end do you start from?

Resistors don’t have a printed arrow telling you which end to read first, but there are reliable tells. The tolerance band is usually gold or silver and sits slightly apart from the tightly-grouped digit and multiplier bands — that gap, and the metallic color, mark the end you should read last, not first. If a resistor looks ambiguous, decode it in both directions; only one direction will produce a value that’s actually manufactured (values follow standard series like E12 or E24, not arbitrary numbers), and that’s almost always the correct reading.

Formatting the answer

Once you have a number in ohms, it’s conventional to simplify it: 1,000Ω becomes 1kΩ, 1,000,000Ω becomes 1MΩ, and anything under 1,000Ω is usually left in plain ohms, like 220Ω or 4.7Ω. Getting comfortable moving between the raw number of ohms and this shorthand makes it much faster to compare resistors at a glance, whether you’re sorting components in a parts bin or double-checking a schematic.

Practice is the fastest way in

Color-code reading is a skill built by repetition rather than memorization of charts. Pull a handful of resistors from an assortment kit, decode each one by eye, then check yourself with a multimeter or a color-code calculator. After a few dozen resistors, the digit sequence starts to read like a word rather than a lookup, and that’s the point where it stops slowing down a build.