How to use this calculator
- Choose the number of bands on the resistor.
- Read the bands from the end opposite the gold or silver tolerance band (the tolerance band is usually set slightly apart).
- Select each band's color.
Formula
The first two (4-band) or three (5- and 6-band) bands are digits, the next is a power-of-ten multiplier, then tolerance, and on 6-band resistors a temperature coefficient.
R = (digits) × multiplier
Black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9
Tolerance: brown ±1%, red ±2%, gold ±5%, silver ±10%
Example
- Yellow, violet, red, gold.
- Digits 4 and 7, multiplier ×100 → 4,700 Ω = 4.7 kΩ.
- Gold = ±5%, so 4.465–4.935 kΩ.
Frequently asked questions
Which end do I start reading from?
Start from the band closest to a lead, away from the gold or silver band. If unsure, the reading that gives a standard E-series value (like 4.7 kΩ) is usually correct.
What if there are only three bands?
A 3-band resistor is a 4-band code without a tolerance band: two digits and a multiplier, with ±20% tolerance.
What does the temperature coefficient mean?
How much the resistance changes per degree Celsius, in parts per million. 100 ppm/K means 0.01% per °C.