How to Read Resistor Color Codes (4-, 5- and 6-Band)

A resistor’s color bands encode its resistance as digits, a multiplier and a tolerance. On a standard 4-band resistor, the first two bands are digits, the third is the power-of-ten multiplier, and the fourth is the tolerance. For example, yellow-violet-red-gold reads 4, 7, ×100, ±5%: 4,700 Ω (4.7 kΩ) ±5%. Read from the end where the bands are bunched together, with gold or silver on the right.

Color codes are used because printed numbers are hard to read on a tiny cylindrical part and can rub off. The system is standardized internationally in IEC 60062.

The resistor color code chart

The digits run in rainbow order from black (0) through brown, red, orange, yellow, green, blue, violet and gray to white (9). A memory aid helps; one example is “Black Bears Roam Over Yellow Grass But Violets Grow Wild.” The multiplier for each color is simply 10 raised to its digit, so orange (3) is ×1,000.

Reading a 4-band resistor

More examples:

A gold or silver third band means a value below 10 Ω, as in the green-blue-gold example.

Reading a 5-band resistor

Precision resistors add a third digit band. The pattern is three digits, multiplier, tolerance.

Notice that 10 kΩ is brown-black-orange on a 4-band part but brown-black-black-red on a 5-band part. The value is the same; only the encoding changes.

Reading a 6-band resistor

A sixth band, after the tolerance, gives the temperature coefficient of resistance in parts per million per kelvin (ppm/K). A brown sixth band means 100 ppm/K: over a 50°C temperature rise, the resistance can drift by 100 × 10⁻⁶ × 50 = 0.005, or 0.5%. Low coefficients matter in measurement circuits, oscillators and anything that must stay accurate as it warms up.

Which end is first?

Getting the direction wrong turns a 4.7 kΩ resistor into nonsense. Clues for finding band 1:

• Gold and silver are never first. If one end is gold or silver, read from the other end.
• Tolerance bands are often set apart with a slightly wider gap.
• The first band is usually closer to the lead than the last band is.
• Check against standard values. If one reading gives a common value such as 4.7 kΩ and the reverse gives something odd, the common value is almost certainly right.

When colors are faded or ambiguous (brown, red and orange can look alike under warm light), measure the part with a multimeter, out of circuit, to confirm.

Tolerance and real resistance

Tolerance gives the range the actual resistance may fall within.

A 4.7 kΩ ±5% resistor can measure anywhere from 4,465 Ω to 4,935 Ω and still be in specification. A 1 kΩ ±1% part ranges from 990 to 1,010 Ω.

Standard values: the E-series

Resistors are not made in every value. They come in preferred-number series defined by IEC 60063, spaced so that each value’s tolerance range roughly meets the next.

That is why 4.7 kΩ, 10 kΩ and 220 Ω are everywhere, while 5 kΩ is rare. When a calculation calls for a non-standard value, pick the nearest standard one or combine resistors; the series and parallel resistor calculator finds combinations.

Surface-mount (SMD) codes

Surface-mount resistors are too small for bands and use printed numbers instead:

Many 1% SMD parts use the EIA-96 code instead, two digits that index a table of E96 values followed by a letter multiplier, so 01C means 100 × 100 = 10 kΩ.

Putting the value to use

Once you know the resistance, Ohm’s law tells you the current and power in your circuit; see Ohm’s law explained and the Ohm’s law calculator. Typical uses include current-limiting LEDs, covered by the LED resistor calculator, and setting voltages with the voltage divider calculator. To decode any band combination instantly, use the resistor color code calculator.