Resistor Color Code Calculator

A resistor color code calculator converts the painted bands on a resistor into its resistance in ohms. Read the digit bands, apply the power-of-ten multiplier, then the tolerance. Example: brown-black-red-gold decodes to 1, 0, ×100 = 1,000 Ω (1 kΩ) ±5%, which may measure from 950 to 1,050 Ω. Pick the number of bands and the color of each one above, and the calculator returns the value in ohms, kΩ or MΩ, the tolerance, the in-spec range and, for 6-band parts, the temperature coefficient.

How the resistance is calculated

The decoding rule is the same for every color-banded resistor; only the number of digit bands changes:

For a 3-band or 4-band resistor you read two digit bands; for a 5-band or 6-band resistor you read three. So brown-black-red (4-band) is the number 10 multiplied by 10² = 1,000 Ω, while brown-black-black-brown (5-band) is the number 100 multiplied by 10¹ = 1,000 Ω. The tolerance band then sets how far the actual value may stray from that nominal figure, and a sixth band, when present, gives the temperature coefficient.

The color-to-number key

Digit and multiplier bands share one sequence, worth memorizing because it underpins the whole system:

• Black = 0, Brown = 1, Red = 2, Orange = 3, Yellow = 4
• Green = 5, Blue = 6, Violet = 7, Grey = 8, White = 9
• Multiplier: the same numbers are used as a power of ten, so red means ×10² = ×100. Gold means ×0.1, silver ×0.01 and pink ×0.001 for small values.
• Tolerance: brown ±1%, red ±2%, green ±0.5%, blue ±0.25%, violet ±0.1%, grey ±0.05%, gold ±5%, silver ±10%, no band ±20%.
• Temperature coefficient (6th band): black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5, grey 1 ppm/K.

Resistor color code chart: what each band color means

One table holds the whole system. The same color means one thing as a digit band, another as the multiplier, a third as a tolerance band and a fourth as a temperature-coefficient band; this chart lists all four roles side by side.

Per IEC 60062 as reproduced in Panasonic's color-code reference. Grey and white multipliers and tolerances tighter than ±0.1% are rare on real parts; when a band seems to call for one, check the datasheet.

How to use this calculator

You only need to look at the resistor and match colors. Work through the controls in order:

1. Count the bands: pick 3, 4, 5 or 6. Four is the most common general-purpose part; five usually means a precision resistor; six adds a temperature coefficient; three means there is no tolerance band.
2. Set the digit bands: choose the color of bands 1 and 2, and band 3 on 5- and 6-band parts. A swatch next to each dropdown helps you match it to the part.
3. Set the multiplier: the band right after the digits, which decides how many zeros (or which decimal place) the value lands on.
4. Set the tolerance: the band slightly set apart from the rest, often gold (±5%), silver (±10%) or brown (±1%).
5. Set the temperature coefficient on a 6-band part: the last band.

The result updates as soon as you change a band: the nominal value at the top, then the min/max range and a band-by-band breakdown. If you are not sure which end is which, start reading from the side where the bands are grouped tightest; the tolerance band sits on the opposite end.

A worked example: a 4.7 kΩ resistor

Suppose you have a 4-band resistor banded yellow-violet-red-gold. Yellow is 4 and violet is 7, giving the number "47". Red as a multiplier is ×10² = ×100, so 47 × 100 = 4,700 Ω = 4.7 kΩ. The gold tolerance band is ±5%, meaning the part may legitimately measure anywhere from 4,465 Ω to 4,935 Ω. That spread is why two resistors from the same bag can read slightly differently and both be correct.

Common resistor values and their 4-band color codes

These are everyday E12 and E24 values, each shown as a 4-band gold (±5%) resistor with the exact range the part may measure. Match your resistor to a row to confirm a reading.

Who this calculator is for

Anyone who has to turn colored stripes into a usable number benefits from it, including:

• Electronics hobbyists sorting a parts bin or following a breadboard tutorial.
• Students learning circuit basics who need to check homework against the color code.
• Makers and repair techs identifying a resistor before swapping it on a board.
• Hardware engineers checking a value quickly without pulling a datasheet.
• Teachers and kit builders who want a reliable reference to share with a class.

3, 4, 5 and 6-band resistors compared

The practical difference is precision. A 4-band resistor (two digits) covers everyday values where ±5% or ±10% is fine: pull-ups, current limiting for LEDs and general logic. A 5-band resistor (three digits) is used where you need a tighter tolerance such as ±1% or better, common in measurement, filters and reference circuits; the extra digit lets the value be specified more exactly, so 100 Ω can be written as brown-black-brown (4-band) or brown-black-black-black (5-band). A 6-band resistor adds the temperature coefficient for circuits that must stay stable as they warm up. A 3-band resistor drops the tolerance band altogether, which means ±20%.

Scenario comparison: same value, different parts

Here is how three common resistors decode, showing why the bands matter:

• Brown-black-orange-gold (4-band): 10 × 10³ = 10,000 Ω = 10 kΩ ±5% (range 9.5 kΩ to 10.5 kΩ).
• Red-red-brown-gold (4-band): 22 × 10¹ = 220 Ω ±5% (range 209 Ω to 231 Ω), a classic LED resistor.
• Brown-black-black-red-brown (5-band): 100 × 10² = 10,000 Ω = 10 kΩ ±1% (range 9.9 kΩ to 10.1 kΩ), the precision version of the first example with a far tighter range.

What affects the real measured value

The color bands give the nominal value, but a multimeter may read something a little different. The main factors:

• Tolerance: the biggest factor; a ±10% part has twice the allowable spread of a ±5% part.
• Temperature: resistance shifts with heat. The temperature coefficient (ppm/K) says by how much: 100 ppm/K means up to 0.01% per degree.
• Lead and contact resistance: for very low values, the test leads and probe contact add a small amount.
• Aging and damage: overheated or stressed resistors can drift out of spec or read open.

How much does the tolerance band change the value?

Tolerance sets the width of the in-spec window. This table takes a single nominal 10 kΩ resistor and shows the range for every tolerance band: the ±5% gold part can legally span a full 1 kΩ, while a ±0.1% violet part is held within 20 Ω.

Why resistors come in odd values (the E series)

Resistors are sold in values like 4.7 kΩ, 5.6 kΩ and 6.8 kΩ rather than tidy 5 kΩ or 6 kΩ steps because they follow the preferred-number series of IEC 60063. Each series has a fixed number of values per decade, spaced by a roughly constant ratio so that neighboring values and their tolerances cover the whole range. The series you meet most often are:

• E6: 6 values per decade (1.0, 1.5, 2.2, 3.3, 4.7, 6.8), traditionally paired with ±20% parts.
• E12: 12 values per decade, adding 1.2, 1.8, 2.7, 3.9, 5.6 and 8.2, traditionally ±10%; this is where most hobby resistors live.
• E24: 24 values per decade, the usual range for general-purpose ±5% parts.
• E96: 96 values per decade for ±1% precision parts, which is why they need a third digit band to express a value like 4.99 kΩ.

Knowing the series is a quick sanity check: if your decoded value is not close to a standard E-series number, you have probably misread a band or read the resistor from the wrong end.

Combining resistors in series and parallel

Decoding one resistor is often only the first step. In a real circuit you frequently need a value that no single part provides, so you combine several:

Two 1 kΩ resistors in series make 2 kΩ; the same two in parallel make 500 Ω. Putting a 10 kΩ and a 22 kΩ in parallel gives 6.875 kΩ when the bag has no 6.8 kΩ part. The Parallel Resistor Calculator handles up to ten parts at once, and the Ohm's Law Calculator gives the current or voltage at that point in the circuit.

Worked example: a current-limiting resistor for an LED

The most common reason hobbyists decode a resistor is to protect an LED. Suppose a red LED needs about 2 V across it and 20 mA (0.02 A), driven from a 5 V supply. The resistor must drop the remaining 3 V, so by Ohm's law R = V ÷ I = 3 ÷ 0.02 = 150 Ω. In the parts bin, a brown-green-brown-gold resistor decodes to 1, 5, ×10¹ = 150 Ω ±5%, exactly right. If you only have a 220 Ω (red-red-brown-gold) part, the LED simply runs a little dimmer at about 13.6 mA, which is usually fine. Decoding the bands first, then checking the value against what the circuit needs, is the everyday workflow this calculator supports.

Special and hard-to-read resistors

A few parts do not follow the everyday pattern, and knowing them prevents head-scratching:

• Zero-ohm resistors carry a single black band and act as a wire jumper. They have no meaningful resistance to decode.
• 3-band resistors omit the tolerance band entirely, which means ±20%. Two digits and a multiplier are all you read.
• 6-band resistors add a temperature-coefficient band after the tolerance band; the first five bands decode exactly like a 5-band part.
• Large power resistors often print the value as text instead of colors, because their bodies have room for it.
• Faded or burned parts: heat can discolor bands until brown looks like red or orange. When in doubt, decode the best guess here and confirm the value with a multimeter before trusting it.

Tips for reading bands accurately

• Find the tolerance band first: gold or silver almost always marks the right-hand (last) band, which fixes the reading direction.
• Use good light: brown, red and orange can look alike under warm light; daylight or a white LED helps.
• Confirm with a meter: if a band is faded or ambiguous, measure the resistor and match it to the nearest standard value.
• Watch for reversed parts: reading from the wrong end turns, say, a 330 Ω part into a nonsense value; the breakdown table here helps you catch it.

Color bands do not tell you the power rating

One thing the color code leaves out is the power rating: how many watts the resistor can dissipate before it overheats. Two resistors with identical brown-black-red-gold bands (1 kΩ ±5%) can have very different power ratings; a tiny 1/8 W part and a chunky 2 W part look the same in code but differ in size. Through-hole resistors commonly come in 1/8 W, 1/4 W, 1/2 W, 1 W and 2 W, each step noticeably larger. To check that a resistor will survive in your circuit, work out the power it dissipates with P = I² × R or P = V² ÷ R and pick a part rated comfortably above that figure; about twice is a common design practice. Confirm wattage from the datasheet or the text on the body for any power-handling application.

What the IEC 60062 standard covers

The color code used on this page is defined in IEC 60062, Marking codes for resistors and capacitors, published by the International Electrotechnical Commission. Besides the color code for resistance, tolerance and temperature coefficient, the standard covers other coding methods for resistance and capacitance values and their tolerances, and date codes for marking small components. Its 2016 edition introduced pink as the code color for a ×10^-3 multiplier and added separate clauses on how resistance value, tolerance and TCR are marked; a 2019 amendment followed. Manufacturers such as Panasonic publish their color code charts "in accordance with IEC 60062," which is why the same colors mean the same numbers across brands.

Telling apart the colors that fool people

Most decoding errors trace back to a handful of look-alike colors, especially on small bodies or under warm lighting:

• Brown vs. red vs. orange: the classic mix-up. Brown is dull and earthy, red is vivid, and orange leans toward amber. Compare them side by side under daylight or a white LED, not a yellowish bulb.
• Gold vs. yellow: gold has a metallic sheen and almost always sits at the far end as the tolerance band, while yellow is a flat digit color earlier in the sequence.
• Violet vs. blue vs. grey: on faded parts these blur together; tilt the resistor under light, or measure it to settle the question.
• Black vs. a shadow: a genuine black band is even; what looks like a faint extra band near a lead is sometimes just a shadow or a printing smudge.

When two readings seem plausible, decode both here and keep the one that lands on a standard E-series value; the wrong reading usually produces an unusual number.

Key terms explained

• Significant digits: the first bands that form the base number before the multiplier is applied.
• Multiplier: the power of ten the digits are scaled by; it sets the magnitude (Ω, kΩ, MΩ).
• Tolerance: the ± percentage the real value may differ from nominal.
• Temperature coefficient (TCR): how much the resistance may change per degree of temperature, in parts per million per kelvin (ppm/K).
• Nominal value: the value the bands declare.
• Preferred (E-series) values: the standard steps of IEC 60063 (E12, E24, E96), which is why you see 4.7 kΩ but rarely 4.85 kΩ.

Limitations and assumptions

This is a decoding aid, not a measurement. Keep these limits in mind:

• It covers 3-band to 6-band color-coded resistors; it does not read the numeric codes printed on surface-mount (SMD) resistors.
• It assumes the bands are read in the correct direction; a reversed part decodes to the wrong value.
• The output is the printed nominal value and its tolerance window; it cannot tell you the true resistance of a specific part.
• It does not report power rating, which depends on the resistor's physical size, not its bands.

Related electronics calculators

This page answers "what resistance do these bands mean?" For the next step in the circuit:

• To work out voltage, current or power from the resistance, use the Ohm's Law Calculator.
• To combine several decoded parts into one value, use the Parallel Resistor Calculator.
• To split a supply voltage with two resistors, use the Voltage Divider Calculator.
• To check losses along a wire run, use the Voltage Drop Calculator.

Sources

• International Electrotechnical Commission: IEC 60062:2016+AMD1:2019, Marking codes for resistors and capacitors (color code; pink ×10^-3 multiplier introduced in 2016; TCR marking).
• Panasonic Industry: Resistor color codes, a manufacturer's chart "in accordance with the IEC 60062 standard" (digits, multipliers, tolerances and TCR values used here).
• International Electrotechnical Commission: IEC 60063:2015, Preferred number series for resistors and capacitors (E series).
• National Institute of Standards and Technology: SI prefixes (kilo, mega and giga used for kΩ, MΩ and GΩ).