How it works
A 4-band resistor has two significant-digit bands, a multiplier band and a tolerance band. A 5-band resistor has three significant-digit bands, then the multiplier and tolerance.
R = (significant digits) × 10^multiplier
Multiplier colors: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. Gold is ×0.1 and silver is ×0.01.
Worked example
Yellow-violet-red-gold is 47 × 10² = 4.7 kΩ with ±5 % tolerance. Brown-black-black-red-brown is 10 kΩ with ±1 % tolerance.
Design tips
- For precision circuits, use 5-band resistors with a tolerance of ±1 % or better (brown or tighter).
- When reading small resistors, check the gold and silver bands first. If the multiplier band is gold, the value is multiplied by 0.1.
- If the colors are hard to tell apart, enter the value to see the band order, then compare with the real part.
Limitations
- Band printing differs between manufacturers, and colors can look different under different lighting. When in doubt, measure with a multimeter.
- The resistor drawing on screen is a schematic view to show the band positions.
Frequently asked questions
How do I tell a 5-band resistor from a 4-band one?
A 5-band resistor has its bands closer together and three significant digits. The last band is the tolerance, so check the position of the gold and silver bands.
What is the tolerance if there is no tolerance band?
Older resistors with only three bands have a tolerance of ±20 %. The calculator treats "none" as ±20 %.