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.

More worked decodes

A handful of full examples, run through the decoder, cover most of what you’ll actually encounter in a parts bin:

• Yellow–violet–orange–gold (4-band): digits 4 and 7 give 47, orange multiplies by 1,000, gold means ±5% — 47,000Ω, or 47kΩ ±5%.
• Orange–orange–red–gold (4-band): digits 3 and 3 give 33, red multiplies by 100, gold means ±5% — 3,300Ω, or 3.3kΩ ±5%.
• Red–red–orange (3-band, no tolerance band at all): digits 2 and 2 give 22, orange multiplies by 1,000 — 22,000Ω, or 22kΩ, with the implied ±20% tolerance that applies whenever a resistor has no fourth band.
• Brown–black–black–red–brown (5-band): three digits, 1, 0, 0, give 100; red multiplies by 100; brown as the tolerance band means ±1% — 10,000Ω, or 10kΩ ±1%.
• Red–red–black–brown–brown (5-band): digits 2, 2, 0 give 220; brown multiplies by 10, giving 220 × 10 = 2,200Ω; brown tolerance means ±1% — 2,200Ω (2.2kΩ) ±1%.

Why the tolerance band is more than a footnote

The tolerance band isn’t just a formality — it tells you the real range the resistor could actually measure at, and that range can matter a lot depending on what the circuit is doing. Take the 47kΩ ±5% resistor above: ±5% of 47,000Ω means the true value could be anywhere from about 44,650Ω to 49,350Ω and still be within spec. Compare that to a 10kΩ ±1% resistor, where the range narrows to 9,900Ω–10,100Ω. And a resistor with no fourth band at all — an implied ±20% — leaves a genuinely wide window: a “22kΩ” resistor with no tolerance band could measure anywhere from 17,600Ω to 26,400Ω and still be a correctly manufactured part.

For a simple LED indicator circuit, a ±20% swing barely matters — the LED still lights, just marginally brighter or dimmer than predicted. For a voltage divider setting a precise reference, or for two resistors in a bridge circuit that need to track each other closely, a loose tolerance can throw the whole measurement off by more than the error you’re trying to detect. That’s the practical reason precision circuits reach for 5-band, 1% (or tighter) parts, while a breadboard LED project is perfectly happy with an ordinary 4-band, 5% or even 20% resistor. See Reading Resistor Color Bands: Why the Tolerance Band Actually Matters for a closer look at when that precision is worth paying for.

Why standard values exist at all

Resistors aren’t manufactured in every possible ohm value — they come from standard series with names like E12, E24, and E96, where the number is roughly how many distinct values are spaced across each decade (1–10, 10–100, 100–1,000, and so on). The spacing isn’t arbitrary: it’s set so that each step is roughly as large as the tolerance band that goes with it, which means every manufactured value’s error range just touches its neighbor’s without leaving gaps or wasteful overlap. A looser E12 series (12 values per decade) pairs naturally with a ±10% or ±20% tolerance; the denser E24 series (24 values per decade) pairs with ±5%; and E96 (96 values per decade) is what makes ±1% parts practical. That’s also why a calculated resistance like 345Ω almost never matches a real part exactly — the nearest real value from the appropriate series is what actually gets bought, generally rounded up rather than down for safety in current-limiting applications like an LED resistor.

Common misreads

• Confusing brown and red, or blue and violet, under poor lighting. These color pairs are the most commonly confused, especially under yellow-tinted indoor lighting. Reading resistors under bright, neutral-white light (or daylight) cuts down on this significantly.
• Treating gold or silver as a digit. They only ever appear as a multiplier or tolerance color, never as one of the significant-digit bands — if a gold or silver band shows up in the digit position, you’re almost certainly reading the resistor backward.
• Guessing at a badly worn or dirty resistor. Handling, heat, and age can dull a resistor’s bands. When a color genuinely can’t be told apart, a multimeter’s resistance mode settles the question directly rather than guessing from a stripe that might be brown, red, or just dirty.

Color bands vs. printed codes

Color bands are the standard for through-hole (leaded) resistors, but they’re not the only marking system in electronics. Small surface-mount resistors are usually too tiny for stripes and instead carry a printed numeric code directly on the body — a different system entirely, read digit by digit rather than color by color. If a project calls for surface-mount parts, that’s worth knowing going in, but every resistor in a typical beginner kit or breadboard project is the leaded, color-banded kind this guide covers.

Putting a decoded value to work

Decoding a resistor is rarely the end goal — it’s usually one step toward confirming a circuit will behave the way you expect. Once you know a resistor’s value, the natural next questions are what current it’ll allow at a given voltage (a job for Ohm’s law) and what it does when combined with other resistors in series or parallel. Decoding two resistors as, say, 220Ω and 470Ω and then feeding those values into the Series/Parallel Resistance Calculator is a common real-world sequence — the color code gets you the individual values, and the next calculation tells you what the combination actually does in the circuit.

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 the Resistor 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.