Resistor colour code calculator

How do you read a resistor's colour bands?

Turn 4, 5 or 6 colour bands into ohms and tolerance, or find the bands of a value.

Resistor

Find

Colour bands

Bands

Band 1: digit

Band 2: digit

Band 3: multiplier

Band 4: tolerance

Resistance

4.7 kΩ ±5%

Between 4.465 kΩ and 4.935 kΩ

How to use

Choose Value to read a resistor, or Colours to find the bands of a resistance.
Hold the resistor with the bands bunched at the left and the gap (often gold or silver) at the right, then pick the colours from left to right.
Read the resistance, its tolerance and the range it may really have. To go the other way, type the value and choose 4, 5 or 6 bands.

Resistance range for a 1 kΩ resistor

Tolerance (%)	Minimum (Ω)	Maximum (Ω)
1	990	1,010
2	980	1,020
5	950	1,050
10	900	1,100
20	800	1,200

How it works

Small resistors are too small for printed numbers, so their value is painted on as coloured rings. Each colour stands for a digit, from black for 0 to white for 9. The next band says how many zeros to add, and a band set apart at the end gives the tolerance: how far the real value may be from the marked one.

On a 4-band resistor the first two bands are digits and the third is the multiplier: yellow (4), violet (7), red (× 100) and gold (±5 %) read 47 × 100 = 4 700 Ω = 4.7 kΩ, so the part is between 4 465 Ω and 4 935 Ω. Precision resistors have 5 bands with three digits, and a sixth band can give the temperature coefficient, how much the value drifts with heat in parts per million per kelvin. Gold and silver as the multiplier mean × 0.1 and × 0.01. The colours and values are those of the standard IEC 60062.

Colours fade and some look alike (red, orange and brown), so when in doubt, measure the resistor with a multimeter out of the circuit. Military and some older parts use other markings.

Frequently asked questions

Which end do I start reading from?

From the end where the bands are closer to the edge. The tolerance band, usually gold or silver, is at the other end, often with a gap before it. Gold and silver are never the first band.

What does a resistor with only three bands mean?

Two digits and a multiplier with no tolerance band: the tolerance is ±20 %.

Why can't my value be shown with 4 bands?

Four bands hold only two digits, so 4.75 kΩ needs 5 bands. Standard 4-band values come from the E12 and E24 series, which the tool suggests next to the bands.

Do the bands tell me the power rating?

No. The bands show resistance and tolerance, and sometimes a temperature coefficient. Check the part specification for its power rating.

What if the colours are faded?

Do not guess. Measure the resistance with the circuit unpowered and the resistor isolated from other current paths.