Resistor Colour Code Calculator

Resistor Colour Code Calculator reads the coloured bands on a through-hole resistor and tells you its resistance, its tolerance range and, for six-band resistors, its temperature coefficient. It also works the other way: type a value such as 4.7k, 4k7 or 220 and it shows which colours to look for. It covers three-band resistors (two digits and a multiplier, ±20%), the common four-band kind (two digits, multiplier, tolerance), and five- and six-band precision resistors (three digits, multiplier, tolerance, and temperature coefficient on the sixth). Colours and their meanings follow IEC 60062:2016. Every answer also says whether the value is a standard one from the E12, E24 or E96 series, and if not, the nearest standard values either side, which is what you can actually buy.

1. Hold the resistor with the tolerance band — usually gold or silver, and set slightly apart — on the right.
2. Choose the number of bands, then pick each band’s colour from left to right.
3. Read the resistance, the range it may fall in, and whether it is a standard value.
4. To go the other way, choose Value to colours, type the resistance and pick a tolerance.

• Colours can be hard to tell apart, especially red, orange and brown, or violet, blue and grey, and some resistors fade with heat. If two readings are possible, measure with a multimeter: it settles it in a second.
• Reading from the wrong end gives a different, usually non-standard value. If the result is not in any E-series, try the bands in reverse order.
• Tolerance and temperature-coefficient colours follow IEC 60062:2016, which changed a few meanings (grey is ±0.01%, orange ±0.05%); older or unusual resistors may use other conventions. A data sheet always wins.
• Surface-mount resistors use printed number codes, not colours; this page does not read those.
• Value to colours needs a value with two significant digits for 3- and 4-band resistors, or three for 5- and 6-band ones; the page says when a value cannot be shown and suggests standard values near it.
• Everything is worked out in your browser. Nothing you choose or type is sent or saved.

4.7 kΩ (4,700 ohms) with a ±5% tolerance, so anything from 4,465 to 4,935 Ω is within specification. It is one of the most common values.

From the end the bands are closer to. The tolerance band (gold, silver, or on precision resistors brown or red) is usually separated by a wider gap and goes on the right.

Sets of preferred values per decade defined in IEC 60063, spaced so that each value’s tolerance range touches the next. E12 has 12 values (for ±10% parts), E24 has 24 (±5%), and E96 has 96 (±1%).

Brown, black, orange and a tolerance band (often gold) on a four-band resistor; brown, black, black, red and the tolerance band on a five-band one.