Resistor Color Code: Complete Reference

1. Introduction

Nearly every discrete resistor available globally features its resistance value indicated through a series of colored bands encircling its body. When interpreted correctly, these bands provide three key pieces of information at a glance: the nominal resistance, the tolerance — which signifies the permissible deviation of the actual value — and, specifically in the case of precision components, the temperature coefficient, which indicates the extent to which the resistance value may vary with changes in temperature.

This guide is designed to serve a dual purpose: it acts both as a detailed step-by-step tutorial for individuals encountering these bands for the first time, and as a highly accurate reference for students and engineers who require exact mappings according to the IEC 60062 standard. It is important to note that every numerical representation provided herein adheres strictly to the international standard, as opposed to relying on anecdotal or folklore charts.

2. What is a resistor?

A resistor is a two-terminal component that opposes the flow of electric current. The opposition it presents is its resistance, measured in ohms (Ω). Ohm's law relates the three core quantities: V = I × R, where V is voltage (volts), I is current (amperes), and R is resistance (ohms).

Because resistance values span many orders of magnitude — from fractions of an ohm to hundreds of megohms — manufacturers print a compact nominal value on the body. Color bands are that compact code. The nominal value is the target the part is made to; the actual resistance of any single part is never exactly nominal, and the tolerance bounds how far it may be.

3. What does a color band represent?

Each band is a position in a small number, not an independent measurement. Reading left to right (from the digit end), the bands encode:

• Significant digits — one or two colors (three on 5/6-band parts) form the leading number, e.g. red–yellow–white → 249.
• Multiplier — a power of ten applied to the digits, e.g. orange → ×10³.
• Tolerance — the allowed manufacturing deviation, e.g. gold → ±5%.
• Temperature coefficient (TCR) — on 6-band precision parts, how much the value changes per degree of temperature, e.g. red → ±50 ppm/K.

Why 4, 5, or 6 bands? More bands = more significant digits = tighter, more precise values. 4-band parts give two significant figures (common in ±5% general-purpose resistors). 5-band parts give three (typical of ±1% precision). 6-band parts add the TCR on top, used where thermal stability matters (oscillators, references, filter networks).

Significant figures matter for reading, not just value: a 5-band part marked 1.00 kΩ communicates three meaningful digits, whereas a 4-band 1 kΩ communicates two. The number of bands tells you how precisely the value is specified.

4. Quick reference

Golden rule: gold and silver are never digits. They only appear as multipliers (×0.1 / ×0.01) or tolerances (±5% / ±10%). If you "read" a gold or silver band as a digit, you've almost certainly started from the wrong end.

5. Complete color table (IEC 60062)

Each column lists the value a color has in that position only. A dash means the color is not used in that position — not every color is valid everywhere.

6. How to read the bands

Use this order every time:

1. Find the tolerance band — it sits at the far end and is usually spaced a little farther from its neighbors. On 4-band parts it's often gold or silver, which are dead giveaways.
2. Read the digit bands first, from the end opposite the tolerance band.
3. Read the multiplier — the last digit-position band before the tolerance.
4. Read the tolerance (and the TCR, if a sixth band is present).
5. Compute R = digits × multiplier, then the tolerance window.

Don't assume a universal physical orientation — some parts are marked at an angle. When a part is genuinely ambiguous, the datasheet or manufacturer marking wins.

7. 4-band resistors

Two significant digits, one multiplier, one tolerance.

Example — Brown · Black · Red · Gold

• Brown = 1, Black = 0 → digits 10
• Red = ×10² = ×100
• Gold = ±5%
• R = 10 × 100 = 1000 Ω = 1 kΩ ±5%

Tolerance window: 1000 × 0.05 = 50 Ω → 950 Ω … 1050 Ω.

Example — Yellow · Violet · Red · Gold

• Yellow = 4, Violet = 7 → digits 47
• Red = ×100 → 47 × 100 = 4700 Ω = 4.7 kΩ ±5%
• Window: 4465 Ω … 4935 Ω (4.465 kΩ – 4.935 kΩ)

8. 5-band resistors

Three significant digits, multiplier, tolerance. The extra digit is why these parts are usually ±1% (or tighter).

Example — Brown · Black · Black · Brown · Brown

• 1, 0, 0 → digits 100; Brown = ×10; Brown = ±1%
• R = 100 × 10 = 1000 Ω = 1.00 kΩ ±1%
• Window: 990 Ω … 1010 Ω.

Example — Red · Yellow · White · Orange · Brown

• 2, 4, 9 → 249; Orange = ×10³; Brown = ±1%
• R = 249 × 1000 = 249,000 Ω = 249 kΩ ±1%
• Window: 246.51 kΩ … 251.49 kΩ.

9. 6-band resistors (with TCR)

Same as 5-band for the resistance, plus a sixth band = temperature coefficient.

Worked — Red · Yellow · White · Orange · Brown · Red

• Red = 2, Yellow = 4, White = 9 → 249
• Orange = ×10³
• Brown = ±1%
• Red (6th) = ±50 ppm/K
• R = 249 × 1000 = 249,000 Ω = 249 kΩ ±1%, TCR ±50 ppm/K

10. Tolerance, explained

Tolerance is the allowed manufacturing deviation around the nominal resistance. A part is guaranteed to land inside nominal ± tolerance, not to be exactly nominal.

Example — 1 kΩ ±5%:

• Deviation = 1000 × 0.05 = 50 Ω
• Minimum = 1000 − 50 = 950 Ω
• Maximum = 1000 + 50 = 1050 Ω

So any "1 kΩ ±5%" resistor you buy is somewhere in 950 Ω … 1050 Ω. Tighter tolerance narrows the window.

11. Temperature Coefficient of Resistance (TCR)

TCR describes how much the resistance changes with temperature, relative to its nominal value.

ppm/K and ppm/°C

"ppm" means parts per million of the nominal value. A TCR of +100 ppm/K means the resistance changes by 100 parts per million (0.0001, or 0.01%) for each kelvin of temperature change. Because a change of 1 K is numerically identical to a change of 1 °C, a TCR quoted in ppm/K has the same number in ppm/°C for temperature differences.

12. The TCR formula

• R₀ = resistance at the reference temperature
• α = temperature coefficient in K⁻¹, where α = TCR / 1,000,000
• ΔT = temperature change

Example — 10 kΩ, +100 ppm/K, +50 °C:

• α = 100 / 1,000,000 = 0.0001 K⁻¹
• ΔR = 10,000 × 0.0001 × 50 = 50 Ω
• R ≈ 10,000 + 50 = 10,050 Ω (10.05 kΩ)

A positive TCR means resistance rises with temperature; a negative TCR means it falls. Color bands specify the TCR as a magnitude/tolerance band; the actual sign and value are given by the component's specification.

13. Worked examples (summary)

14. Common mistakes

• Reading from the wrong end — you'll hit gold/silver as a "digit", which is impossible; that's your cue to flip direction.
• Confusing tolerance with multiplier — gold is ×0.1 as a multiplier but ±5% as a tolerance; position decides the meaning.
• Treating gold/silver as digits — they never are.
• Forgetting the third digit on 5/6-band parts — 249, not 24.
• Misreading the 6th band as a second tolerance instead of the TCR.
• Confusing tolerance with TCR — one is a manufacturing spread, the other is thermal drift.
• Forgetting ppm = parts per million (÷1,000,000), not per hundred.
• Treating tolerance as temperature drift — tolerance is fixed at manufacture; TCR changes it with heat.
• Rounding too early — keep full precision until the final display.
• Assuming one universal convention — SMD parts use printed numbers, not bands.
• Ignoring the datasheet when a marking is ambiguous or faded.

15. Which end do I read from?

Locate the tolerance band first — it's usually the one set slightly apart at the end, and on 4-band parts it's frequently gold or silver. Read the digit bands from the opposite end. Treat "farther-spaced tolerance band" as a strong heuristic, not a law — and when in doubt, check the component's datasheet or manufacturer marking.

16. Interactive decoder

Pick a band count, choose each band's color, and the result updates live. Each band only offers the colors that are valid in that position (per IEC 60062), so invalid combinations can't be entered; the decoder re-validates on every change and reports any problem in plain language.

17. Practice problems

Try each one, then reveal the answer. Nothing is hidden permanently.

Beginner

Intermediate

Advanced

18. Quick cheat sheet

B=black Br=brown R=red O=orange Y=yellow G=green B=blue V=violet Gr=grey W=white Gd=gold Sl=silver. (Letters are mnemonics only — always confirm on the part.)

19. Frequently asked questions

20. Technical references

• IEC 60062 — Marking codes for resistors and capacitors. Primary source for the digit, multiplier, tolerance and TCR color mappings used above (current edition as available to the project).
• Component manufacturer datasheets and marking guides (for part-family-specific conventions, e.g. 5-band-with-TCR vs 6-band layouts).