Resistor Color Code Calculator (3, 4, 5 and 6 Band)

Background.

Resistors are too small to print a number on, so since the middle of the twentieth century they have carried their value as a ring of coloured bands. The system is compact, survives being covered in flux and solder, and can be read from any angle — but it is also the single most common source of quiet errors on a hobby bench, because two of the failure modes look exactly like success. Read the bands from the wrong end and you get a real, plausible number that happens to be wrong by orders of magnitude. Miscount a 5-band part as a 4-band part and you get a real, plausible number that is wrong by a factor of ten. This calculator removes both by asking you how many bands there are first, then decoding them and telling you what it used.

Enter the band count, pick each colour from the dropdowns in the order they appear on the part, and you get the nominal resistance, the tolerance limits it is allowed to fall between, the temperature coefficient if there is a sixth band, and a preferred-value check that flags the most likely reading mistakes. The band count is not cosmetic. On a 4-band resistor the first two bands are significant figures and the third is the multiplier. On a 5-band resistor the first three are significant figures and the fourth is the multiplier. Yellow-violet-red is 4.7 kΩ on a 4-band part; the same three colours on a 5-band part are the digits 4, 7 and 2, waiting on a multiplier that has not been read yet.

The coding is defined by IEC 60062, "Marking codes for resistors and capacitors", currently in its sixth edition (2016). Manufacturers reference it directly: Vishay's MRS16 and MRS25 metal-film datasheet states that "four or five color code rings designate the resistance value and tolerance according to IEC 60062", and Vishay's own printed colour card is headed "According to IEC 60062" for the bands and "According to IEC 60063" for the values they are allowed to take. That second standard matters more than most people realise, and it is why this page includes a preferred-value check.

IEC 60063 defines the E-series: the small sets of significant figures that resistors are actually manufactured in. E6 has six values per decade and pairs with ± 20 % parts; E12 has twelve and pairs with ± 10 %; E24 has twenty-four and pairs with ± 5 %; E96 has ninety-six and pairs with ± 1 %. The values are spaced so that consecutive tolerance bands just touch, which is why 47 exists and 45 does not. The practical consequence for reading colour codes is powerful: if your decode produces a two-figure value that is not in E24, or a three-figure value that is not in E96, you have almost certainly read the resistor from the wrong end. This calculator says so explicitly rather than handing you a confident wrong number.

A few reading habits are worth building. The tolerance band is usually set slightly apart from the others and is often physically wider, which is how you find the correct end; gold and silver in the last position are a strong tell, because neither can be a significant figure. A black first band is impossible for the same reason a phone number cannot start with a leading zero that means anything, so if you decode one, turn the part round. And on very low-value parts, gold and silver reappear as fractional multipliers — a gold multiplier divides by ten, a silver one divides by a hundred — which is how current-sense shunts down in the milliohms are marked.

Two limits are worth stating before you rely on a number from this page. First, the colour code gives you the marked value, not the measured value: a ± 5 % 4.7 kΩ part is in specification anywhere between 4,465 Ω and 4,935 Ω, and both of those are printed below the main result for exactly that reason. Second, the sixth band is the least standardised part of the whole scheme. The tolerance and multiplier assignments are stable across every source; the temperature-coefficient colours are not shown identically by every manufacturer, and Vishay's own card lists fewer of them than the full IEC table does. Where this calculator uses a colour that Vishay does not show, it says so beside the answer.

What is resistor color code calculator?

A resistor colour code is a positional numeral system printed as rings of paint. Each band occupies a position with a fixed meaning, and each colour has a fixed value in that position, so the whole value is recovered by reading positions in order.

The digit colours run in spectrum order: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9. The multiplier band uses the same colours to mean powers of ten — black is x 1, brown x 10, red x 100 and so on up to white at x 1,000,000,000 — plus gold for x 0.1 and silver for x 0.01. The tolerance band uses a different assignment again: brown ± 1 %, red ± 2 %, green ± 0.5 %, blue ± 0.25 %, violet ± 0.1 %, grey ± 0.01 %, orange ± 0.05 %, yellow ± 0.02 %, gold ± 5 %, silver ± 10 %, and no band at all for ± 20 %.

So one colour can mean three different things depending on where it sits. Red is the digit 2, or the multiplier x 100, or the tolerance ± 2 %. That positional overloading is why the band count has to be established before anything else can be decoded, and why this calculator asks for it as the first field rather than trying to guess.

The number of bands tracks precision. Three and four band parts carry two significant figures, which is enough for ± 5 % and looser tolerances where the E24 series has only twenty-four values per decade. Five and six band parts carry three significant figures because a ± 1 % part comes from the E96 series, which needs three figures to distinguish 475 from 487. The sixth band, where present, is the temperature coefficient in parts per million per kelvin — the rate at which the resistance drifts as the part warms up, which is the specification that matters in precision references and instrumentation amplifiers.

How to use this calculator.

1. 01Find the correct end first. Look for the band that is set slightly apart from the rest, or is noticeably wider — that is the tolerance band, and it goes last. Gold or silver in an end position is the clearest tell of all, because neither colour can be a significant figure.
2. 02Count every coloured ring, including the one you just identified as the tolerance band, and set the band-count dropdown to match. This is the step people skip, and it is the step that turns a 5-band 1 kΩ into a 4-band 100 Ω.
3. 03Read the colours left to right from the end opposite the tolerance band, and set them in the dropdowns in that order.
4. 04On a 3 or 4 band part, leave the third-figure dropdown alone — it is ignored. On a 3 band part the tolerance dropdown is ignored too, and ± 20 % is applied automatically.
5. 05Check the 'Bands as read' line against the resistor in your hand before you trust the number. It reproduces exactly what the calculator used, in order.
6. 06Read the preferred-value check. If it tells you the value is not in E6, E12, E24 or E96, reverse the colours and try again — a decode that lands outside every manufactured series is almost always a reading-direction error.
7. 07Use the minimum and maximum in-spec values, not the nominal one, when the resistor sets a current, a gain or a divider ratio that has to hold in the worst case.
8. 08If the part has six bands, treat the temperature-coefficient result as a starting point and confirm it against the manufacturer's datasheet. This band is the least consistently marked part of the scheme.

The formula.

The decode is a base-ten place-value read followed by one multiplication.

The significant-figure bands are concatenated into a single integer D. On a 3 or 4 band resistor there are two of them, so D = 10 x d1 + d2 and runs from 10 to 99. On a 5 or 6 band resistor there are three, so D = 100 x d1 + 10 x d2 + d3 and runs from 100 to 999. The first digit cannot be zero, which is why a black first band is rejected rather than silently read as a leading zero.

The multiplier band supplies an exponent m, and the nominal resistance is R = D x 10^m. Because D is an integer and 10^m is an exact power of ten, R is exact — no rounding happens at this stage, and none is needed. Yellow-violet-green-orange gives D = 475 and m = 3, so R = 475 x 1,000 = 475,000 Ω exactly.

The tolerance band supplies a percentage t. The in-spec limits are R x (1 − t/100) and R x (1 + t/100). These are the only two figures on the page that are rounded, and the rounding happens once, at the end, to ten decimal places — well below any resolution you could measure. A 3-band resistor has no tolerance band; IEC 60062 assigns the absent band ± 20 %, so that is what this calculator reports rather than leaving the field blank.

The preferred-value check works on D directly, as an exact integer, never on a rounded or displayed value. A two-figure D is tested against the E6, E12 and E24 sets from IEC 60063 and the tightest matching series is reported, since E6 is a subset of E12 which is a subset of E24. A three-figure D is tested against E96, and separately against E24 after dividing by ten, because a 5-band part codes a ± 5 % series value such as 47 as 470. Because the test is integer equality, it cannot be thrown off by floating-point error at a boundary.

The temperature coefficient is a lookup, not a computation: the sixth band's colour maps to a value in parts per million per kelvin, and the result states which colours are confirmed on a manufacturer's own colour card and which appear only in the broader IEC table.

A worked example.

Frequently asked questions.

References& sources.

1. [1]IEC 60062:2016, "Marking codes for resistors and capacitors", International Electrotechnical Commission, sixth edition, July 2016. The governing standard for the band assignments used on this page — significant figures, multipliers, tolerances and the temperature-coefficient band. The full text is a paid document; the preview and scope statement were retrieved 2026-07-29, and the tables below were taken from sources that reproduce it and are cited separately.
2. [2]Vishay Draloric / Beyschlag / BCcomponents, "Resistor Color Card", document VMN-MS6212-1501 (2015). A manufacturer's own colour card, headed "According to IEC 60062" for the band coding and "According to IEC 60063" for the standard values. Read directly on 2026-07-29: it lists the ten tolerance values used here (± 10, ± 5, ± 2, ± 1, ± 0.5, ± 0.25, ± 0.1, ± 0.05, ± 0.02, ± 0.01 %), the multipliers x 1 through x 1 M plus divide-by-ten and divide-by-a-hundred, the temperature coefficients 100, 50, 25, 15, 10 and 5 ppm/K, the full E24 and E96 tables, and the worked example "4 7 5 x 1k ± 1 % = 475k ± 1 %" used as this page's example.
3. [3]Vishay BCcomponents, "MRS16, MRS25 Professional Thin Film Leaded Resistors", document 28724, revision 07-Mar-16. States plainly that "four or five color code rings designate the resistance value and tolerance according to IEC 60062", and gives the accompanying electrical specification: rated dissipation P70 of 0.4 W (MRS16) and 0.6 W (MRS25), maximum operating voltage 200 V and 350 V, peak permissible film temperature 155 °C. Retrieved and read 2026-07-29.
4. [4]Vishay, "D/CRCW e3 Standard Thick Film Chip Resistors", document 20035, revision 14-Apr-2026. Independent confirmation of the tolerance and temperature-coefficient values in commercial production: resistance tolerance ± 5 % and ± 1 %, temperature coefficient ± 200 ppm/K and ± 100 ppm/K, rated dissipation quoted as P70 — the power rating at 70 °C ambient — with permissible film temperature 155 °C. Retrieved and read 2026-07-29.
5. [5]IEC 60063:2015, "Preferred number series for resistors and capacitors", third edition, 27 March 2015. Defines the E3, E6, E12, E24, E48, E96 and E192 series that the preferred-value check on this page tests against, and the tolerance each series pairs with: E6 with ± 20 %, E12 with ± 10 %, E24 with ± 5 %, E96 with ± 1 %. Retrieved 2026-07-29 via the reference summary of the series values and their standard tolerances.
6. [6]"Electronic color code", reference article citing IEC 60062:2016, retrieved 2026-07-29. Reproduces the full colour table used here — digit, multiplier, tolerance and temperature coefficient for every colour including the gold, silver and no-band rows — and notes the gap between the multiplier and tolerance bands that distinguishes the reading direction. Used as one of two independent reproductions of the paid standard; the second is the Pro Certs Software resistor colour-code guide, which agrees value for value.
7. [7]Pro Certs Software, "Resistor Colour Codes — A Complete Guide", retrieved 2026-07-29. The independent second reproduction of the IEC 60062 tables used to cross-check every value on this page, including the nine temperature-coefficient colours (black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5, grey 1 ppm/K). Agrees with the first reproduction in every cell.