Resistor Color Code Calculator
Pick 4 or 5 resistor color bands and read the resistance in ohms with a k/M/G prefix and tolerance, checked against a live band preview.
The sum: 1 (Brown) 0 (Black) × 10² (Red) = 1000 Ω = 1 kΩ
How to read it: hold the resistor with the tolerance band — gold or silver, usually set a little apart — on the right, and read from the left. The first bands are digits, the next multiplies them by a power of ten, and the last is the tolerance.
Color code table
What this resistor color code calculator does
Choose how many color bands your resistor has — usually 4 or 5 — then set the color of each band from the dropdowns. An old part with no tolerance band at all can be entered as it is: the page reads the missing band as the wide tolerance it stands for and says so. The tool instantly converts the bands into a resistance value in ohms — automatically adding a k, M, or G prefix — and shows the tolerance. A live band preview mirrors your selections so you can double-check the color order against the physical part. The classic brown, black, red, gold combination, for example, reads out as 1 kΩ ±5%. “Show in” beside the answer writes it in Ω, kΩ, MΩ or GΩ instead of the prefix Auto picks, and the Copy text and the range follow it. The “Common values” row sets the bands for an everyday resistance in one click, keeping the tolerance band already chosen, and in Resistance → Colors it fills in the value instead.
How the color bands are read
Each color maps to a fixed value: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, and white 9. On a 4-band resistor the first two bands are significant digits, the third is a power-of-ten multiplier, and the fourth is the tolerance. A 5-band resistor adds a third significant digit before the multiplier. Multipliers extend to gold (×0.1) and silver (×0.01) for small resistances, while the tolerance band says how far the real part may differ from that value; where a color meant a different tolerance on older parts, a note under the answer says so. The calculator multiplies the digits by the multiplier and reports the matching tolerance, and a line headed The sum under the answer spells that multiplication out in your own colors, with the reading instruction beside it. The folded Color code table lists every color's digit, multiplier, tolerance and temperature coefficient, so the mapping can be checked at a glance.
SMD resistor codes
A surface-mount resistor is printed with a code instead of bands. Choose “SMD code → Resistance” and type the “Marking on the part”: three digits are two figures and a power of ten (473 is 47 kΩ), four digits are three figures and a power of ten (4701 is 4.7 kΩ), an R stands where the decimal point goes (4R7 is 4.7 Ω), an EIA-96 code is two digits that pick a value from the E96 series and a letter that multiplies it (01C is 10 kΩ), and a marking of zeros alone is a zero-ohm jumper. The page says which kind of code it read and the tolerance parts marked that way usually carry, and “Show in” works here too.
Frequently asked questions
How do I know which end to start reading from?
Hold the resistor so the tolerance band — usually gold or silver, and often spaced slightly apart — is on the right. Then read the bands left to right into the calculator. If a value looks wrong, try reversing the order.
What is the difference between a 4-band and 5-band resistor?
A 4-band resistor uses two significant digits, a multiplier, and a tolerance band. A 5-band resistor adds a third significant digit before the multiplier, giving higher precision — common on tighter-tolerance parts. Pick the matching mode at the top before setting the colors.
Does it read the temperature-coefficient band?
Yes. The extra band on a precision resistor gives its temperature coefficient in ppm per degree Celsius, and it works both ways — colours to value, and value to colours.
Can I see how the value is worked out?
Yes. Under the answer, the line headed The sum writes the arithmetic in your own colors — the digit bands read as a number, times the multiplier band, equals the resistance — with how to hold and read the part beside it. Open Color code table below the calculator for every color's digit, multiplier, tolerance and temperature coefficient in one table.
Can it read the printed code on an SMD resistor?
Yes. Choose “SMD code → Resistance” and type the “Marking on the part”: three digits (473 is 47 kΩ), four digits (4701 is 4.7 kΩ), an R where the decimal point goes (4R7, R47), an EIA-96 code of two digits and a letter (01C is 10 kΩ), or zeros alone for a jumper. The page says which kind of code it was and the tolerance parts marked that way usually carry.