The colour code of IEC 60062
The colour bands are read from the end they are closer to. For four bands: R = (10·a + b) · 10^m, where a and b are the digits of the first two bands, m is the exponent of the multiplier and the fourth band gives the tolerance. The digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The multiplier of gold is 0.1, silver 0.01, pink 0.001. Tolerance: gold ±5 %, silver ±10 %, brown ±1 %, red ±2 %, green ±0.5 %, blue ±0.25 %, violet ±0.1 %, grey ±0.01 %, orange ±0.05 %, yellow ±0.02 %; without a tolerance band ±20 %.
Three, four, five and six bands
Three bands: two digits and a multiplier, tolerance ±20 %. Four: a tolerance band is added. Five: three digits, a multiplier and a tolerance, used for precise values of the E48 and E96 series. Six: a temperature coefficient of resistance (TCR) is added to the five: black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5, grey 1 ppm/K. Example: red, red, black, brown, brown is 220 × 10 = 2.2 kΩ ±1 %. Some makers use non-standard colours and extra bands, so check a doubtful value with a multimeter.
The series E6, E12, E24, E48, E96
The IEC 60063 standard lists the preferred values. They follow roughly a geometric progression with the ratio 10^(1/N), where N is 6, 12, 24, 48 or 96. E6 contains 1.0, 1.5, 2.2, 3.3, 4.7, 6.8 (tolerance ±20 %), E12 adds six more values (±10 %), E24 gives 24 values (±5 %), E48 with ±2 % and E96 with ±1 % are written with three digits. If the value you need is not in a series, take the nearest one: the calculator shows its difference in percent and the neighbouring values above and below.
SMD resistor markings
A chip resistor carries three digits: 472 is 47 × 10² = 4.7 kΩ. A four-digit code has three significant digits: 4992 is 499 × 10² = 49.9 kΩ. Small values use the letter R in place of the decimal point: 4R7 = 4.7 Ω, R47 = 0.47 Ω; the letters K and M show kilohms and megohms: 8K2 = 8.2 kΩ. A zero-ohm jumper is marked 0 or 000. An EIA-96 code has two digits (the position in E96 from 01 to 96) and a multiplier letter: Z 0.001, Y or R 0.01, X or S 0.1, A 1, B or H 10, C 100, D 1000, E 10 000, F 100 000, applied to the three-digit number 100–976. So 01C is 100 × 100 = 10 kΩ.
How to use the calculator
Choose a mode. In the first set the number of bands and the colour of each, in the second enter a value and a tolerance to get the colours, in the third enter the code from the body or a value to get its code. The solution shows how each band was read and the table of series gives the nearest standard values. The link to the calculation is copied at the bottom of the form.