Four-band resistors are common in general-purpose through-hole circuits. Their code has two significant digits, a multiplier, and a tolerance. The fourth band is often spaced farther away, which can help identify the reading direction. For a fast check, enter the four colors in the Resistor Color Code Calculator; the result updates as each color is selected.
The four positions
| Band | Role | What it means |
|---|---|---|
| 1 | First significant digit | Black is not normally valid here; brown through white represent 1 through 9. |
| 2 | Second significant digit | Black is valid here and represents 0. |
| 3 | Multiplier | Applies the power-of-ten or fractional multiplier. |
| 4 | Tolerance | Shows the allowed initial deviation from nominal value. |
The formula is (10 x first digit + second digit) x multiplier. Gold and silver are not digits, but they can be multipliers of x0.1 and x0.01. Gold at the fourth position means +/- 5 percent; the position changes the meaning.
Worked four-band examples
| Code | Calculation | Result |
|---|---|---|
| Brown, Black, Red, Gold | 10 x 100 | 1 kohm +/- 5% |
| Yellow, Violet, Orange, Gold | 47 x 1,000 | 47 kohm +/- 5% |
| Yellow, Violet, Red, Gold | 47 x 100 | 4.7 kohm +/- 5% |
| Red, Red, Brown, Silver | 22 x 10 | 220 ohm +/- 10% |
| Orange, Orange, Black, Gold | 33 x 1 | 33 ohm +/- 5% |
| Brown, Black, Gold, Gold | 10 x 0.1 | 1 ohm +/- 5% |
| Brown, Black, Silver, Silver | 10 x 0.01 | 0.1 ohm +/- 10% |
| Green, Blue, Black, Gold | 56 x 1 | 56 ohm +/- 5% |
| Grey, Red, Brown, Gold | 82 x 10 | 820 ohm +/- 5% |
| White, White, White, Brown | 99 x 1,000,000,000 | 99 Gohm +/- 1%; unusual, verify the part |
How to identify the reading direction
Look for the grouped digit and multiplier bands, then the larger gap before tolerance. Gold and silver are common tolerance colors, but brown, red, orange, yellow, green, blue, violet, and grey can also be used in precision tables. The first significant digit cannot normally be black, gold, or silver. These clues are not a substitute for the datasheet: a rotated, faded, or damaged part may leave two plausible directions.
For example, brown-black-red-brown reads as 1 kohm +/- 1% in one direction. If the physical spacing is unclear, enter the reverse candidate separately and compare it with the schematic or an isolated meter reading. The calculator uses the order you enter; it does not inspect the component orientation.
When colors and a multimeter disagree
- Turn off power and discharge the circuit using the equipment procedure.
- Check whether another resistor or circuit path is in parallel.
- Lift one lead or remove the component if an in-circuit reading is not independent.
- Compare the stable reading with the nominal tolerance range.
- Check meter accuracy, probe resistance, temperature, and possible part drift.
A color code does not reveal power rating, maximum voltage, pulse capability, construction, or safety approval. Those properties must come from the complete part specification.
Three-band and five-band boundaries
Brown-black-red with no fourth band is a three-band code and is commonly treated as +/- 20%, not a four-band part with missing information. Brown-black-black-brown-gold is a five-band code: the third black is a significant digit, so it represents 1 kohm +/- 5% rather than the four-band interpretation.
Common questions
Can the second band be black?
Yes. Black is digit 0 and is often the second band in values such as 10 ohm, 100 ohm, 1 kohm, and 10 kohm.
Can gold be the third band?
Yes. In the third position it is a x0.1 multiplier; in the fourth position it is usually +/- 5% tolerance.
Is a four-band result enough to choose a replacement?
No. Match resistance, tolerance, power, voltage, construction, temperature coefficient, pulse requirements, and the manufacturer specification.
Source and limits
This guide follows IEC 60062-style resistor color marking practice and the color/value conventions used in common through-hole manufacturer tables. Color decoding identifies the nominal marking; it does not prove that a particular part is genuine, undamaged, correctly installed, or available in the stated power rating.
- Use the Resistor Color Code Calculator as a reading aid, then compare the result with the component body, schematic, bill of materials, and datasheet.
- Gold, silver, faded paint, unusual spacing, and manufacturer-specific marks can create more than one plausible reading.
- Do not use a color-only result as a safety, installation, procurement, customs, or compliance decision.
Related guides
Which Way to Read focuses on orientation; Reading Faded Bands covers uncertain paint; and Verify With a Multimeter covers measurement technique.