Resistor Color Code Calculator
Pick the color bands on a 4-band or 5-band resistor to read off its resistance and tolerance.
Resistor value
Why resistors use a color code
Most resistors are too small to print numbers on legibly, so manufacturers settled on a standardized color code decades ago (now formalized as IEC 60062). Once you know the digit values, the code is fully mechanical: read the significant digits, multiply by the power of ten the third band encodes, and note the tolerance from the last band.
The same logic runs in reverse when you’re choosing a resistor for a project: pick the value you need, look up which color bands produce it, and you can identify the right part in a mixed bag without a multimeter.
Frequently Asked Questions
How does the resistor color code work?
Each color stands for a digit: black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, violet=7, grey=8, white=9. On a 4-band resistor the first two bands are significant digits, the third is a multiplier (a power of ten, 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 for tighter precision.
What does the tolerance band mean?
Tolerance is how far the actual resistance can differ from the printed value: gold is ±5%, silver ±10%, brown ±1%, red ±2%, and no fourth band at all means ±20%. A 1kΩ resistor with a gold band could measure anywhere from 950Ω to 1050Ω and still be within spec.
Which end do I read the bands from?
Start from the band closest to one end of the resistor — the tolerance band (often gold or silver, and usually a bit further from the others) is the giveaway that you're reading in the right direction. If you're not sure, decode it both ways; only one direction will give a sensible, commonly-manufactured value.
Why do some resistors have 5 bands instead of 4?
5-band resistors add a third significant digit, giving finer resolution (e.g. 4.7 kΩ vs. 4.75 kΩ) and are typically used for tighter 1% or 2% tolerance parts, common in precision circuits.
Educational tool only. Manufacturing tolerance means the actual resistance can differ from the calculated value — verify with a multimeter for anything precision-critical.