UtilityBaseCalculators
Resistor Color Code Calculator
Decode 4- and 5-band resistor colors to ohms, with a live visual of the bands.
Updated July 8, 2026
How to use the resistor color code calculator
- 1Choose 4-band or 5-band to match your resistor.
- 2Set each band's color with the swatched dropdowns. The illustration updates live.
- 3Read the value, tolerance, and real min–max range.
- 4Compare against your schematic or multimeter reading.
Common uses
- Identifying resistors for Arduino, breadboard, and repair projects
- Double-checking a part before soldering it somewhere annoying to unsolder
- Learning the color code with instant visual feedback
- Sorting a mixed drawer of salvaged resistors
Frequently asked questions
How do I know which end to read from?
The tolerance band, gold or silver on common parts, goes on the right, and it's usually separated from the others by a slightly larger gap. Gold and silver never appear as first digits, so if your reading starts with one, flip the resistor.
What's the difference between 4-band and 5-band?
4-band gives two significant digits × multiplier, typical of ±5% general-purpose resistors. 5-band adds a third digit for precision parts (±1%, ±0.5% and tighter). A 4-band can encode 4.7kΩ but a 5-band can encode 4.75kΩ.
What does the tolerance actually mean?
The manufacturer's guarantee on how far the real resistance can stray: a 1kΩ ±5% part measures anywhere from 950Ω to 1,050Ω. The calculator shows this range explicitly. For voltage dividers and precision analog work, that spread matters; for a current-limiting LED resistor it rarely does.
Is there a trick for memorizing the color order?
The digit sequence black-brown-red-orange-yellow-green-blue-violet-grey-white maps to 0–9. Most people learn it with a mnemonic sentence for B-B-R-O-Y-G-B-V-G-W; after a dozen real resistors the wheel sticks on its own.
About this tool
The resistor color code calculator decodes band colors into resistance: pick the colors on a live resistor illustration and read the value in ohms, kilohms, or megohms with the tolerance percentage and the actual min–max range that tolerance implies. Both common formats are supported, 4-band for standard ±5% parts and 5-band for precision resistors with a third significant digit. Color dropdowns show real swatches, which matters because half the difficulty of reading resistors is telling red from orange from brown on a tiny component. Built for electronics classes, Arduino projects, and repair work where the schematic says 10kΩ and the drawer says brown-black-orange.
Like most tools on UtilityBase, the resistor color code calculator runs entirely in your browser. Nothing you enter is uploaded or stored on a server. It's free to use with no account required. Browse more calculators here.
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