Resistor Color Codes

Most small resistors do not have their value printed on them in numbers. Instead they carry rings of color, and each color stands for a number. This page explains that color code from the beginning: what the bands mean, a table of every color, worked examples, how to read a real part the right way around, and why the last band (the tolerance) matters. It also has a resistor simulator: pick a color for each band and the value is worked out as you go.

1. Resistors and their values

A resistor is a small part made to oppose the flow of electric current by a fixed, known amount. That opposition is called resistance. Resistors are used to limit current (for example, so a light-emitting diode does not burn out), to split a voltage into a smaller one, and for many other jobs. Article 3, Resistors, explains how they work and what they are made of.

Resistance is measured in ohms, written with the Greek capital letter omega, Ω. A resistance of 1 Ω lets a current of 1 ampere flow when 1 volt is across it; in general, resistance is the voltage divided by the current, R = V / I.^[1] (Voltage is the electrical "push" and current is the flow of charge; the Ohm's Law helper explains both from the start.)

Resistor values range from a fraction of an ohm to many millions of ohms, so we use the standard metric prefixes: k (kilo) means a thousand, M (mega) means a million and G (giga) means a billion.^[2] So 4,700 Ω is written 4.7 kΩ, and 2,200,000 Ω is 2.2 MΩ. Note the capital M: a small m means one thousandth.

The value marked on a resistor is its nominal value, the value it is designed to have. No resistor is made perfectly, so the real value is a little higher or lower. The tolerance says how far off it is allowed to be, as a percentage of the nominal value.^[3] The color code tells you both.

2. Why colors?

The common leaded resistor is a small cylinder, often only a few millimeters long, with a wire (a lead) at each end. The color code paints its value as rings around the body. International standard IEC 60062, "Marking codes for resistors and capacitors," sets the rules: the bands are expected to go all the way around the body, and at least two thirds of each band must be visible from any angle.^[4] So however the part lies on a bench or a circuit board, you can read it without turning it, which printed numbers on such a tiny cylinder could not promise.

Surface-mount resistors, the tiny flat chips soldered onto the surface of modern circuit boards, use printed number codes instead; Article 3 covers those in Reading surface-mount codes.

3. What each band means

The most common pattern has four bands. The first three are close together near one end; the fourth sits a little apart near the other end and is wider. IEC 60062 requires the tolerance band to be at least 1.5 times as wide as the others, so it cannot be mistaken for them.^[4] Read from the end where the bands are bunched:^[4]​^[3]

1. Band 1: first digit. The first significant digit of the value. "Significant digits" are the digits that carry the number before any zeros are tacked on: in 4,700 they are 4 and 7.
2. Band 2: second digit. The second significant digit.
3. Band 3: multiplier. What to multiply the two digits by. Each multiplier is a power of ten (1, 10, 100, 1,000 and so on), so in practice the multiplier band tells you how many zeros to add after the digits. Red means ×100, two zeros. Gold and silver mean ×0.1 and ×0.01, for values under 10 Ω.
4. Band 4: tolerance. How far the real value may be from the nominal value. Gold is ±5% and silver is ±10%; the sign ± means "plus or minus."

So the recipe is: write down the two digits, add the number of zeros the multiplier says, then attach the tolerance. Figure 2 does this for brown, black, red, gold.

4. The color table

The same ten colors stand for the digits 0 to 9 in every digit band and for the powers of ten in the multiplier band. Gold, silver and (rarely) pink are used only as multipliers or tolerances.^[4]

Values from IEC 60062:2016+AMD1:2019, Table 1.^[4] The 2016 edition also added pink as a multiplier of ×0.001; you are unlikely to meet it. Older charts, including the U.S. Navy's, leave the tolerance column blank for orange through gray.^[5] Where charts disagree, the table above follows the current standard.

Remembering the order

The digit colors 2 to 7 (red, orange, yellow, green, blue, violet) are simply the colors of the rainbow in order. SparkFun's tip is to take "ROY G. BIV," drop indigo, put black and brown in front and gray and white at the end.^[3] If you prefer a sentence, the U.S. Navy's training course uses "Bad Boys Run Over Yellow Gardenias Behind Victory Garden Walls," one word per color from black (0) to white (9).^[5]

5. The simulator

The resistor below works like a real one. Each band is a color picker: click or tap a band and a list opens showing every color it can be, each with its swatch and its name. Choose one and the list closes, leaving just the color on the band, as it would look on a real part. The value, the tolerance range and a band-by-band key update as you go.

• Only colors that make sense for each band are offered. The first band has no black, because a value never starts with a zero; the tolerance band offers "None," which leaves that spot bare and means ±20%.^[4]
• The 5 bands switch adds a third digit band (see section 8). Switching keeps the same value where it can.
• The last line checks whether the value is a standard value, one of the E-series values that resistors are actually made in (section 9).^[6] If it is not, a real part was probably misread.
• With a keyboard: press Tab to reach a band, Enter or the arrow keys to open it, arrow keys or a letter to move, Enter to choose and Escape to cancel.

6. Worked examples

Each example follows the same steps: digits, then multiplier, then tolerance. The simulator's example buttons load each of these.

Brown, black, red, gold

Brown = 1, black = 0, so the digits are 10. Red multiplier = ×100. 10 × 100 = 1,000 Ω = 1 kΩ. Gold = ±5%, so 950 Ω to 1,050 Ω.^[3]

Red, red, orange, gold

Red = 2, red = 2: 22. Orange = ×1,000. 22 × 1,000 = 22,000 Ω = 22 kΩ, ±5% (20.9 kΩ to 23.1 kΩ).

Yellow, violet, red, gold, and yellow, violet, orange, gold

Yellow = 4, violet = 7: 47. With a red multiplier (×100) that is 4.7 kΩ.^[3] Change only the third band to orange (×1,000) and it becomes 47 kΩ, ten times as much.^[7] That is why the multiplier band matters most: misread a digit and you are a little off; misread the multiplier and you are off by a factor of ten.^[5]

Red, violet, orange, silver

This is the U.S. Navy's example. Red = 2, violet = 7: 27. Orange = ×1,000, so 27,000 Ω = 27 kΩ. Silver = ±10%, and 10% of 27,000 is 2,700, so the real value is somewhere between 24,300 Ω and 29,700 Ω.^[5]

Violet, green, yellow, gold

The example in the standard itself: violet = 7, green = 5: 75. Yellow = ×10,000. 75 × 10,000 = 750 kΩ, ±5%.^[4]

Yellow, violet, gold, gold

Digits 47. A gold multiplier means ×0.1, so 47 × 0.1 = 4.7 Ω. The last gold band is the tolerance, ±5%. A gold or silver third band always means a value under 10 Ω (gold) or under 1 Ω (silver).^[5]

Blue, gray, red (only three bands)

Blue = 6, gray = 8: 68. Red = ×100: 6.8 kΩ. There is no tolerance band, which means ±20%.^[4]​^[7]

7. Reading a real resistor

The color table is the easy part. The hard part with a real resistor is finding which end to start from and telling similar colors apart. Work through these steps.

1. Find the tolerance band. On a 4-band part it is usually gold or silver.^[3] It is the wider band, and it is set a little apart from the others.^[4]​^[3] Turn the resistor so that band is on your right.
2. Read from the other end. The first band is the one nearest its end of the body.^[4] Read left to right: digit, digit, multiplier, tolerance.
3. Sanity-check the first band. Gold and silver have no digit value, so they can never be first.^[4] If you find gold or silver at your left, you are holding it backwards (Figure 3). Black is never first either, because a value does not start with a zero.
4. Check the result is a standard value. Resistors are made in a fixed set of values, the E-series (section 9). Values such as 10, 22, 47 and 68 (times any power of ten) are standard; a reading such as 29 or 74 is not, so look again.^[6]
5. Use good light. Brown, red and orange look alike under yellowish lamps, and so do blue, violet and gray. Use daylight or a bright white light and a magnifier if you need one. Most technicians misread a band at some point.^[5]
6. When in doubt, measure. A multimeter set to measure resistance (Ω) gives the answer directly. See below.

Checking the value with a multimeter

A multimeter is a handheld meter that measures voltage, current and resistance. To check a resistor:

• Turn off the power to the circuit first, and discharge any capacitors.^[8] The meter works out resistance by applying a small known voltage of its own and measuring what results, so any voltage already in the circuit gives a wrong reading.^[9]
• Plug the black lead into COM and the red lead into the VΩ jack, set the dial to resistance (Ω) and touch the leads to the two ends of the resistor.^[8] A resistor has no polarity, so either lead can go on either end.^[9]
• Measure the resistor out of the circuit if you can, or lift one end. In a circuit, other parts connected alongside it give the current extra paths, which usually makes the reading too low.^[8]
• Do not hold both metal probe tips or both resistor leads with your fingers: your body becomes one of those extra paths. This matters most for high values.^[8]

The reading should fall inside the tolerance range worked out from the bands (allowing a little for the meter's own accuracy). Article 3 has more in Testing a resistor.

8. Five bands (and three and six)

Four bands give only two significant digits, which is enough for the common 5% and 10% values. Precision resistors need three digits (for example 249 or 102), so they use five bands: three digits, then the multiplier, then the wider tolerance band.^[4] The multiplier is the fourth band, so it is one step smaller than on a 4-band part with the same value: brown, black, black, brown, brown is 100 × 10 = 1 kΩ, the same value as brown, black, red, gold on a 4-band part. Five-band parts always have a colored tolerance band, usually brown (±1%) or one of the tighter colors.^[7]

Another example: orange, orange, black, brown, violet is 330 × 10 = 3.3 kΩ, ±0.1%.^[7] Switch the simulator to 5 bands to try your own.

• Three bands. Two digits and a multiplier, with no tolerance band. The missing band means ±20%.^[4]
• Six bands. A 5-band code plus a sixth band for the temperature coefficient of resistance (TCR): how much the value changes as the part warms, in parts per million per degree. Red in that position means ±50 ppm per kelvin (a kelvin is the same size step as a degree Celsius). The tolerance band stays the single wide band.^[4] Article 3 explains TCR in The four numbers that describe a resistor.
• Old military parts. Older U.S. military-specification resistors added a fifth band after the usual four that gave a failure-rate (reliability) level, not a digit: brown, red, orange or yellow for 1%, 0.1%, 0.01% or 0.001% per 1,000 hours.^[5] If a five-band reading makes no sense as three digits, this may be why.

9. Tolerance and why it matters

Tolerance is the range, in percent, within which the real resistance may differ from the nominal value when the part is delivered.^[10] To find the range, work out the percentage of the nominal value and subtract and add it:

lowest = R × (1 − tolerance/100)    highest = R × (1 + tolerance/100)

For 1 kΩ ±5%: 5% of 1,000 is 50, so the part may be anything from 950 Ω to 1,050 Ω.^[3] At ±1% the range shrinks to 990 Ω to 1,010 Ω.

Why it matters

Every calculation you do with a resistor's value inherits its tolerance. Suppose 5 V is across a 1 kΩ ±5% resistor. By Ohm's law the current is I = V / R,^[1] so:

• at the nominal 1,000 Ω: 5 ÷ 1,000 = 5.0 mA (milliamperes, thousandths of an ampere);
• at the lowest, 950 Ω: 5 ÷ 950 ≈ 5.26 mA;
• at the highest, 1,050 Ω: 5 ÷ 1,050 ≈ 4.76 mA.

About ±5% in current, as you would expect. For an LED's current-limiting resistor or a pull-up resistor, that hardly matters. For a circuit that sets a time delay, a filter frequency or a measured voltage, it can, and there you choose 1% parts. You can try these numbers in the Ohm's Law calculator.

Tolerance and the standard values

Resistors are not made in every value. Standard IEC 60063 sets out the E-series of preferred values, and pairs each series with a tolerance.^[6] The series name gives the number of values in each factor of ten:

• E12 (±10%): 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82.^[6]
• E24 (±5%): the E12 values plus 11, 13, 16, 20, 24, 30, 36, 43, 51, 62, 75, 91.^[6]
• E48 (±2%) and E96 (±1%): three-digit values such as 100, 102, 105 and 249, which is why 1% parts need five bands.^[6]

The values repeat in every decade (factor of ten): 4.7 Ω, 47 Ω, 470 Ω, 4.7 kΩ and so on. The spacing is chosen so that the tolerance ranges of neighboring values just meet: Vishay describes the spreads of two successive values as overlapping slightly.^[10] For example, 4.7 kΩ ±5% covers 4,465 to 4,935 Ω, and the next E24 value, 5.1 kΩ ±5%, covers 4,845 to 5,355 Ω. Between them, every value is covered by some standard part. Article 3 lists the full E24 table in Why resistors come in odd values.

Tolerance is not the whole story

Tolerance describes the part as delivered. In use, the value also moves with temperature (the TCR above) and drifts slowly with heat, load and age.^[10] So a resistor that measures a little outside its tolerance after years in a hot box is not necessarily faulty; one that is far outside it, or reads as an open circuit, is.

Summary

• Colors stand for digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, white 9. Gold and silver are multipliers (×0.1, ×0.01) or tolerances (±5%, ±10%).
• 4 bands: digit, digit, multiplier, tolerance. 5 bands: three digits, multiplier, tolerance. 3 bands: no tolerance band, ±20%.
• Read from the end where the bands are bunched; the wide band, set apart, is last. Gold or silver is never first.
• Check the result is a standard E-series value, and measure with a meter when in doubt.
• Tolerance is the allowed spread: 1 kΩ ±5% is 950 to 1,050 Ω. Use tighter tolerance where precision matters.

For how resistors work, see Article 3, Resistors. To use a value once you have read it, see the Ohm's Law helper; for the resistor's symbol on a circuit drawing, see Schematic Symbols.

Sources

All links were checked in October 2026. External links open in a new tab.

1. OpenStax, College Physics 2e, section 20.2, "Ohm's Law: Resistance and Simple Circuits": https://openstax.org/books/college-physics-2e/pages/20-2-ohms-law-resistance-and-simple-circuits
2. NIST, Guide for the Use of the International System of Units (SI) (SP 811), chapter 4, "The Two Classes of SI Units and the SI Prefixes" (Table 5): https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-4-two-classes-si-units-and-si-prefixes
3. SparkFun Learn, "Resistors" tutorial, section "Decoding Resistor Markings" (all pages): https://learn.sparkfun.com/tutorials/resistors/all
4. IEC 60062:2016+AMD1:2019, "Marking codes for resistors and capacitors", clause 3, "Colour code for fixed resistors" (Table 1 and Figures 1 to 4; free preview pages, PDF): https://cdn.standards.iteh.ai/samples/20940/b5fb592a1a1749c79f33e4d987f7fefb/IEC-60062-2016.pdf
5. U.S. Navy, NEETS Module 1: Introduction to Matter, Energy, and Direct Current, chapter 1, "Standard Color Code System" and "Simplifying the Color Code", pages 1-43 to 1-46 and Table 1-1 (PDF): https://legacy.maritime.org/doc/neets/mod01.pdf
6. IEC 60063:2015, "Preferred number series for resistors and capacitors" (Tables 1 to 3; free preview pages, PDF): https://cdn.standards.iteh.ai/samples/21131/0b431abe83d64551accdfaebc210796e/IEC-60063-2015.pdf
7. Tony R. Kuphaldt, Lessons In Electric Circuits, Volume V (Reference), chapter 2, "Color Codes" (resistor color code examples 1 to 6): https://www.ibiblio.org/kuphaldt/electricCircuits/Ref/REF_2.html
8. Fluke, "How to Measure Resistance with a Digital Multimeter": https://www.fluke.com/en-us/learn/blog/digital-multimeters/how-to-measure-resistance
9. NI (National Instruments), "Digital Multimeter Measurement Fundamentals" (section "Resistance Measurements with a DMM"): https://www.ni.com/en/shop/electronic-test-instrumentation/digital-multimeters/dmm-measurement-fundamentals.html
10. Vishay Beyschlag, application note 28771, "Basics of Linear Fixed Resistors" (nominal value, tolerance, TCR and stability; PDF): https://www.vishay.com/docs/28771/basics.pdf