Resistor color code calculator for through-hole bands and SMD markings
This resistor color code calculator turns the coloured bands on a through-hole resistor into its value, tolerance and temperature coefficient, with a live drawing that updates as you pick each colour. It works for 4-band, 5-band and 6-band resistors, and it also runs in reverse: type a value such as 4.7k or 2M2 and it shows the band colours for both the 2-digit and 3-digit schemes.
Surface-mount parts carry printed codes instead of bands, so a third mode decodes 3-digit and 4-digit markings, the R-as-decimal-point style (4R7, R22) and the EIA-96 system (01A, 68C), and encodes any value into those markings. Every result is checked against the E6–E192 standard series, so you can tell at a glance whether a value is a stock part.
How to use the Resistor Color Code Calculator
- Choose 4, 5 or 6 bands to match the resistor in front of you. Hold the resistor so the tolerance band (gold or silver, or the band set slightly apart) is on the right.
- Pick each band’s colour from left to right. The resistor drawing and the value update immediately.
- Read the resistance, tolerance range and (for 6-band parts) the temperature coefficient, plus the nearest standard values.
- To go the other way, switch to “Value → bands”, type a value like 220, 4.7k, 4k7 or 1M and choose the tolerance; both band schemes are drawn.
- For an SMD part, switch to “SMD code”, type the printed marking (or a value to encode) and read the result with the equivalent markings.
Resistor Color Code Calculator features
4, 5 and 6 bands
Two or three significant digits, a multiplier from ×0.01 (silver) to ×10⁹ (white), tolerance from ±0.05 % to ±20 % and the TCR band in ppm/K.
Live resistor drawing
An SVG resistor is redrawn with your colours so you can compare it with the physical part.
Reverse lookup
Any value becomes band colours; if a value such as 1234 Ω cannot be expressed with 2 or 3 significant digits, the nearest representable value is drawn and flagged.
E-series check
Each value is tested against E6–E192 and the nearest standard value in every series is listed, handy when a calculated value must be bought as a stock part.
SMD and EIA-96 codes
Decodes 3-digit, 4-digit, R-notation and EIA-96 markings, including 0 Ω jumpers, and encodes values back to all three.
How the bands are read
For a 4-band resistor the first two bands are significant digits, the third is the multiplier (the number of zeros, or ×0.1 for gold and ×0.01 for silver) and the fourth is the tolerance. A 5-band resistor adds a third significant digit before the multiplier, which is how precision (±1 % and better) values such as 4.99 kΩ are marked. The sixth band, when present, is the temperature coefficient in parts per million per kelvin.
| Bands | Reading | Value |
|---|---|---|
| Red – Red – Brown – Gold | 22 × 10, ±5 % | 220 Ω ±5 % |
| Yellow – Violet – Red – Gold | 47 × 100, ±5 % | 4.7 kΩ ±5 % |
| Brown – Black – Black – Red – Brown | 100 × 100, ±1 % | 10 kΩ ±1 % |
| Orange – Orange – Silver – Silver | 33 × 0.01, ±10 % | 0.33 Ω ±10 % |
| Yellow – Violet – Black – Red – Brown – Red | 470 × 100, ±1 %, 50 ppm/K | 47 kΩ ±1 % 50 ppm/K |
SMD resistor codes
E-series values are spaced logarithmically so that adjacent values overlap at their tolerance limits: E24 (±5 %) has 24 values per decade (1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1), E12 (±10 %) every second one, E6 (±20 %) every fourth, while E48, E96 and E192 follow 10^(n/48), 10^(n/96) and 10^(n/192) rounded to three figures.
- 3-digit: two significant digits and a multiplier digit — 472 = 47 × 10² = 4.7 kΩ, 100 = 10 Ω, 105 = 1 MΩ. Used on ±5 % parts.
- 4-digit: three significant digits and a multiplier — 1001 = 100 × 10 = 1 kΩ, 4991 = 4.99 kΩ. Used on ±1 % parts.
- R notation: R marks the decimal point for values below 10 Ω — 4R7 = 4.7 Ω, R22 = 0.22 Ω, 0R0 or 000 = 0 Ω jumper.
- EIA-96: two digits give the position (01–96) in the E96 table and a letter gives the multiplier — A ×1, B ×10, C ×100, D ×1 k, E ×10 k, F ×100 k, X/S ×0.1, Y/R ×0.01, Z ×0.001. So 01A = 100 Ω, 22B = 1.65 kΩ and 68C = 49.9 kΩ.
Practical tips
- Red and orange, or brown and violet, are easy to confuse on a dark body. Measure with a multimeter when it matters.
- If the first band seems to be gold or silver you are holding the resistor backwards.
- Once you know the value, the Ohm’s law calculator gives current and power, and the 555 timer calculator and capacitor code calculator cover the other parts on the board.
Resistor Color Code Calculator FAQ
What is the colour code for a 220 Ω resistor?
Red, red, brown, gold for a 4-band ±5 % part (22 × 10). A 5-band ±1 % version is red, red, black, black, brown (220 × 1).
How do I know which end of the resistor to start from?
The tolerance band — gold, silver or the band set slightly apart from the others — goes on the right. If the first band is gold or silver you have it backwards. The calculator draws the resistor in the same orientation.
What does the sixth band mean?
It is the temperature coefficient of resistance in ppm/K: brown 100, red 50, orange 15, yellow 25, blue 10, violet 5. A 50 ppm/K resistor changes by 0.25 % over a 50 K temperature rise.
How do I read SMD resistor codes like 472 or 01A?
Switch to SMD mode. 472 means 47 followed by 2 zeros = 4.7 kΩ; 01A is an EIA-96 code meaning 100 Ω (position 01 = 1.00, A = ×1). R stands for the decimal point: 4R7 = 4.7 Ω.
Why does the calculator say my value is not a standard value?
Manufacturers only make values from the E-series. If you calculated 4.6 kΩ you will have to buy 4.7 kΩ (E24) or 4.64 kΩ (E96); the nearest options in every series are listed.
Does gold always mean ±5 %?
As a tolerance band, yes. As the third band of a 4-band resistor (the multiplier position) gold means ×0.1 and silver means ×0.01, giving values below 10 Ω.