Resistor Color Code Calculator

On a 4-band resistor the first two bands are digits, the third is a multiplier and the fourth is tolerance. A 5-band resistor adds a third digit band before the multiplier, giving three significant figures.

Brown 1 and Black 0 form the digits 10, Red multiplies by 100, giving 1000 ohm, and Gold sets the tolerance at plus or minus 5 percent. The tool formats this as 1 kohm +-5%.

As a multiplier, gold means times 0.1 and silver means times 0.01, used for resistances below ten ohms. As a tolerance band, gold is plus or minus 5 percent and silver is plus or minus 10 percent.

Black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8 and white 9. The same colour order sets the multiplier as that power of ten.

The tool scales the number into ohm, kohm, Mohm or Gohm and trims float noise, so 4700 ohm reads as 4.7 kohm. The exact ohm value is also shown under the formatted figure for reference.

Read from the end where the bands are grouped together. The tolerance band usually sits alone after a wider gap, so keep that band on the right as you enter the colours.

Yes. Switch to 5 bands to use three digit bands, which is common on 1 percent precision resistors such as Brown, Black, Black, Brown, Brown for 1 kohm.

Yes. The engine accepts both grey and gray for the value 8, so either spelling decodes to the same digit and multiplier.

No. The decoding happens entirely in your browser, so it is free, private and keeps working offline once the page has loaded.