Resistor Color Code Calculator
Decode 4-band and 5-band resistor color codes
Resistor Color Code Calculator tool
Results
Resistance
Tolerance
0%
Min Value
0.00 Ω
Max Value
0.00 Ω
Resistor Color Code Calculator: key facts
- What it does
- Decode 4-band and 5-band resistor color codes
- Category
- Science Calculators
- Cost
- Free, with no account, sign-up, or install.
- Your data
- Runs entirely in your browser — the files and text you enter are never uploaded to a server.
- Last reviewed
- . Report an incorrect result.
What the Resistor Color Code Calculator does
Resistor color codes are a standardized system for marking resistance values on through-hole resistors using colored bands. The Resistor Color Code Calculator decodes 4-band and 5-band resistor color codes to determine resistance values and tolerance, and can also find the correct color bands for a desired resistance value. It also supports SMD (surface mount device) resistor codes.
Electronics hobbyists identify resistors in circuits, students learn the color code system, and engineers verify component values during PCB assembly. The calculator displays resistance in appropriate units (Ω, kΩ, MΩ) along with the tolerance range showing minimum and maximum acceptable values.
Because calculations run entirely in your browser using JavaScript, you can decode resistor values without any data leaving your device. The visual color display helps you verify the correct band colors against actual components.
Using the Resistor Color Code Calculator, step by step
- Select the resistor mode from the dropdown: 4-band, 5-band, or SMD code.
- For band resistors, choose the color for each band from the color dropdown menus in order from left to right.
- For SMD resistors, enter the 3 or 4-digit code printed on the component.
- Click Calculate to determine the resistance value.
- View the resistance in ohms, kilohms, or megohms along with the tolerance range.
- Copy the results to your clipboard for documentation or reference.
Reading the bands
Resistor colour coding is a positional system. In the four-band scheme the first two bands are significant digits, the third is a power-of-ten multiplier, and the fourth gives tolerance. Five-band resistors add a third significant digit for tighter precision, shifting the multiplier and tolerance bands along one place.
The digit values follow a fixed sequence from black at zero through to white at nine, with the multiplier band using the same colours as powers of ten. Gold and silver appear only as multipliers of 0.1 and 0.01 and as the common 5% and 10% tolerances, which is why a gold band almost always sits at the tolerance end.
The tool also reports the resulting tolerance range, since a nominal value alone is only part of the specification. Knowing that a nominal 1 kΩ part may legitimately measure anywhere from 950 to 1050 Ω explains a great many puzzling meter readings.
- The defaults — brown, black, red, gold — read as 1 and 0 giving 10, times the red multiplier of 100: 1 kΩ at ±5%, so anywhere from 950 to 1050 Ω.
- Yellow, violet, orange, gold is 47 × 1,000 = 47 kΩ ±5%, one of the most common values in circulation.
- Brown, black, black, brown, brown on a five-band part is 100 × 10 = 1 kΩ at ±1% — the same nominal value to a tighter specification.
What makes this one worth using
- Decoding runs fully client-side, so the tool keeps working without an internet connection and nothing about your components is ever transmitted.
- Supports 4-band, 5-band, and SMD resistor codes in one tool, covering most resistor types encountered in electronics work.
- Displays resistance in appropriate units (Ω, kΩ, MΩ) automatically based on the calculated value.
- Shows the tolerance range (minimum and maximum values) to understand the acceptable variation in resistance.
Practicalities of reading a real resistor
Orientation is the first difficulty, because the bands are not always obviously grouped. The convention is to keep the tolerance band — commonly gold or silver, and often separated by a wider gap — on the right. Reading a resistor backwards is easy to do and produces a wildly wrong value, so if a reading gives an implausible result, try it the other way round.
Colour identification is the second. Brown, red, and orange are genuinely hard to distinguish under poor light, on small parts, or on components discoloured by heat, and red-green colour vision deficiency makes several pairs unreliable. A multimeter settles any doubt in seconds and is worth reaching for before soldering something in.
Two things the colour code does not tell you: the power rating, which is indicated by physical size rather than by any band, and the temperature coefficient, which appears as a sixth band on some precision parts. Note too that standard resistors come in preferred value series, so a decoded value that is not a recognisable E-series number is a good sign the bands have been misread.
Frequently Asked Questions
How do I read resistor color codes?
For 4-band resistors: the first two bands are significant digits, the third is the multiplier, and the fourth is tolerance. For 5-band resistors: the first three bands are significant digits, the fourth is the multiplier, and the fifth is tolerance. Read bands from left to right, with the tolerance band (usually gold or silver) on the right.
What are the standard resistor color codes?
Standard digit color codes are: Black(0), Brown(1), Red(2), Orange(3), Yellow(4), Green(5), Blue(6), Violet(7), Grey(8), White(9). Multipliers include Black(×1), Brown(×10), Red(×100), Orange(×1K), Yellow(×10K), Green(×100K), Blue(×1M), Violet(×10M), Gold(×0.1), Silver(×0.01).
What tolerance values are available?
Standard tolerance color codes are: Brown(±1%), Red(±2%), Green(±0.5%), Blue(±0.25%), Violet(±0.1%), Grey(±0.05%), Gold(±5%), Silver(±10%). Tolerance indicates the maximum deviation from the marked resistance value.
Does this calculator support SMD resistors?
Yes, the calculator supports SMD (surface mount device) resistor codes. For 3-digit codes, the first two digits are significant and the third is the multiplier. For 4-digit codes, the first three are significant and the fourth is the multiplier. An 'R' indicates a decimal point.
How do I find colors for a desired resistance?
Enter the desired resistance value and tolerance, then use the calculator in reverse mode to find the correct color bands. This is useful when you need to find a resistor with specific characteristics in your inventory.
