Resistor Color Code Calculator
Select how many bands your resistor has, then pick each band color from the body toward the tolerance end. We return the nominal resistance, tolerance, acceptable range, and temperature coefficient when a sixth band is present.
Calculate
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Result
The formula
Axial through-hole resistors encode value with colored bands (IEC 60062). Digits form a significand; the next band is a decade multiplier; a following band is tolerance; an optional sixth band is the temperature coefficient in ppm/K. Read bands starting at the end opposite the tolerance (or TCR) mark.
Worked example
- 4-band: brown, black, red, gold
- Digits 1 and 0 → 10; red multiplier ×100 → 1,000 Ω
- Gold tolerance → ±5% (950 Ω – 1,050 Ω)
Result: 1 kΩ ±5%
How resistor color codes are decoded
Choose 4, 5, or 6 bands, set each color, and we apply the standard digit, multiplier, tolerance, and TCR tables. Results use engineering prefixes (Ω, kΩ, MΩ, GΩ) for readability.
Four-, five-, and six-band layouts
Four bands: two digits, multiplier, tolerance (common carbon-film parts, often ±5% gold). Five bands: three digits, multiplier, tolerance (typical metal-film ±1% or better). Six bands add a TCR band after tolerance for precision resistors.
Digit, multiplier, and tolerance colors
Digits run black=0 through white=9. Multipliers reuse those colors as powers of ten, plus gold×0.1 and silver×0.01. Common tolerances include brown ±1%, red ±2%, green ±0.5%, blue ±0.25%, violet ±0.1%, gold ±5%, silver ±10%, and no band ±20%.
Reading direction
Start at the end with bands packed closer to the lead, away from a wider gap before the tolerance (and TCR) band. Gold or silver near one end almost always marks tolerance or a fractional multiplier — never a first digit.
What we do not model
No power rating, body size, failure modes, or non-IEC specialty markings (military three-digit codes, SMD numeric codes). Always confirm critical values with a multimeter.
Interesting facts
IEC 60062 is the reference
The International Electrotechnical Commission standard IEC 60062 defines letter/digit and color marking for resistors and capacitors. Color-band calculators map that table into ohms and percent tolerance.
E-series preferred values
Manufacturers stock values from E6, E12, E24, E96 (and denser) preferred-number series so a decoded “47 kΩ” matches a real catalog part rather than an arbitrary number.
Why gold and silver appear
Gold and silver are reserved for multipliers and tolerances — they are not digit colors — which is why a gold band near the end is read as ±5% (or ×0.1 when it is the multiplier on a four-band part).
TCR in ppm per kelvin
A sixth band states how much resistance drifts with temperature (e.g. brown = 100 ppm/K). That matters in precision analog circuits more than in ordinary LED current-limiting.
Frequently asked questions
Read two digit bands, then the multiplier, then tolerance. Example: brown-black-red-gold → 10 × 100 = 1,000 Ω with ±5% tolerance.
Five-band parts add a third significant digit for finer values (often E96), then multiplier and tolerance. Four-band parts use only two significant digits.
As the last (tolerance) band it means ±5%. As the multiplier on a four-band resistor it means ×0.1. Gold is never a digit color.
Begin at the end where colored bands sit closer together. The tolerance band (often gold or silver) is separated by a wider gap and sits nearer the other lead.
It is the temperature coefficient of resistance (TCR) in ppm/K — how much the value changes per degree. Select “6 bands” in this calculator to include it.
No. Chip resistors use numeric or EIA-96 codes printed on the body, not axial color bands. Use a dedicated SMD decoder or the datasheet marking guide.
Tolerance allows a spread around nominal, aging and heat shift real parts, and misreading band order is common. Trust a calibrated meter for circuit troubleshooting.
Black (0) is unusual as a leading digit on real parts; brown through white (1–9) are typical. This tool still accepts black so you can explore the full table.
References
- IEC 60062 — Marking codes for resistors and capacitors International standard that defines resistor color and letter/digit marking.
- NIST Guide to the SI SI treatment of the ohm and related electrical units.
- OpenStax College Physics — Resistance and resistors Introductory physics chapter on resistance and Ohm’s law context.