Resistor Color Code Calculator
Decode color bands to resistance values or encode a value to color bands.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Resistor Color Code Calculator
Resistors use color bands printed on the body to indicate their resistance value and tolerance. This calculator works in two directions: decode color bands to find the resistance value, or encode a resistance value to find the correct color bands.
- Choose a mode. Select "Decode" to read color bands and find the resistance value, or "Encode" to enter a resistance value and get the color bands.
- For decoding: Select 4 or 5 bands, then choose the color of each band from left to right. The first bands are significant digits, the next is the multiplier, and the last is the tolerance.
- For encoding: Enter the resistance in ohms and select the number of bands and desired tolerance.
- Read the result. The calculator shows the resistance value in appropriate units and the color band sequence.
About Resistor Color Codes
The resistor color code was standardized in the 1920s to mark small resistors that are too small to print numbers on directly. Each color represents a digit (black=0, brown=1, red=2... white=9), a multiplier power of ten, and a tolerance range. Four-band resistors provide two significant digits; five-band resistors provide three, allowing more precise values.
The tolerance band tells you how much the actual resistance can vary from the marked value. Gold is ±5%, silver is ±10%, and colored bands (brown, red, etc.) indicate tighter tolerances used in precision circuits.
Frequently Asked Questions
How do I read a 4-band resistor color code?
Hold the resistor with the tolerance band (gold or silver) on the right. Read left to right: the first two bands are significant digits (e.g., red=2, violet=7 gives 27), the third band is the multiplier (e.g., orange=×1000), and the fourth band is tolerance (gold=±5%). So red-violet-orange-gold = 27,000 Ω = 27 kΩ ±5%.
What is the difference between a 4-band and 5-band resistor?
A 4-band resistor has two significant digits plus a multiplier and tolerance band, giving two-digit precision (e.g., 47, 100, 220 Ω). A 5-band resistor adds a third significant digit, giving three-digit precision (e.g., 147, 1000, 2210 Ω). Five-band resistors are used when tighter tolerances (1% or 2%) require more significant figures to be meaningful.
What does the gold band on a resistor mean?
Gold in the tolerance position (last band) means the resistor's actual value is within ±5% of its marked value. Gold can also appear as a multiplier band in the third position, where it represents a multiplier of 0.1. So a resistor with gold in the multiplier position has a value less than its first two digits (e.g., brown-green-gold = 15 × 0.1 = 1.5 Ω).
Which direction do I read the color bands?
Read from left to right, with the tolerance band (usually gold or silver) on the right side. If the resistor has bands that look symmetric and you cannot identify the tolerance band, check which end has a wider gap between the last band and the body. If still unsure, measure with a multimeter. This calculator's decode mode lets you try both orientations and see which gives a standard E24 value.