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Resistor Color Code Calculator
Decode a 4-band resistor from its color bands.
Resistance
—
From the color bands.
| Tolerance | — |
|---|---|
| Minimum | — |
| Maximum | — |
| — |
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Enter your figures above to see the step-by-step working.
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How the Resistor Color Code Calculator Works
A four-band resistor encodes its value in colored stripes. The first two bands are digits, the third is a multiplier (a power of ten), and the fourth is the tolerance. Black is 0, brown 1, red 2, on through white at 9. Read the first two as a two-digit number, multiply by the third band, and you have the resistance. Brown-black-red is 10 × 100 = 1,000 ohms, or 1 kΩ, and a gold band means ±5%.
Hold the resistor with the tolerance band (usually gold or silver) on the right. The tolerance tells you how far the real value can stray — a 1 kΩ ±5% resistor measures somewhere between 950 and 1,050 ohms.
resistance = (digit₁ digit₂) × multiplier
Frequently Asked Questions
How do you read a resistor color code?
The first two bands are digits, the third multiplies by a power of ten, and the fourth is tolerance. Combine the digits and multiply.
What color is the tolerance band?
Usually gold (±5%) or silver (±10%). Keep it on the right so you read the bands in the correct order.
What is brown-black-red?
1, 0, ×100 = 1,000 ohms, or 1 kΩ. With a gold band it’s 1 kΩ ±5%.
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