A resistor color code gives a nominal resistance and, when present, a tolerance. Tolerance is the permitted initial deviation from that nominal value at a stated reference condition; it is not a lifetime guarantee and it is not a substitute for the part datasheet. The Resistor Color Code Calculator shows the tolerance alongside the decoded value so you can interpret the range rather than only the headline ohms.
What the tolerance band means
For a 1 kohm resistor marked gold, +/- 5 percent means a nominal range of 950 to 1,050 ohms. Silver at +/- 10 percent gives 900 to 1,100 ohms. Brown at +/- 1 percent gives 990 to 1,010 ohms. Actual readings are also affected by meter accuracy, temperature, lead resistance, circuit connections, aging, and overload history.
Complete tolerance reference
| Band color | Tolerance | Where it is used | Example range for 1 kohm |
|---|---|---|---|
| Brown | +/- 1% | Precision tolerance position | 990 to 1,010 ohms |
| Red | +/- 2% | Precision tolerance position | 980 to 1,020 ohms |
| Orange | +/- 0.05% | Reference table; verify series | 999.5 to 1,000.5 ohms |
| Yellow | +/- 0.02% | Reference table; verify series | 999.8 to 1,000.2 ohms |
| Green | +/- 0.5% | Precision tolerance position | 995 to 1,005 ohms |
| Blue | +/- 0.25% | Reference table; verify series | 997.5 to 1,002.5 ohms |
| Violet | +/- 0.1% | Reference table; verify series | 999 to 1,001 ohms |
| Grey | +/- 0.01% | Reference table; verify series | 999.9 to 1,000.1 ohms |
| Gold | +/- 5% | Common general purpose | 950 to 1,050 ohms |
| Silver | +/- 10% | Wider tolerance | 900 to 1,100 ohms |
| No band | Commonly +/- 20% | Three-band convention | 800 to 1,200 ohms |
The precision entries above follow this common reference table. Orange, yellow, and grey values are not a promise that every resistor series uses those tolerance bands; confirm the specific part.
Gold and silver: multiplier or tolerance?
The band position controls the meaning. In the multiplier position, gold is x0.1 and silver is x0.01. In the final tolerance position, gold is +/- 5 percent and silver is +/- 10 percent. Brown, black, gold, gold is therefore 1 ohm +/- 5 percent, while brown, black, gold as a three-band code is 1 ohm with the common unstated +/- 20 percent convention.
Three-, four-, five-, and six-band positions
| Format | Tolerance position | What a missing tolerance means here |
|---|---|---|
| 3-band | Not shown | Commonly treated as +/- 20%; verify the part |
| 4-band | Band 4 | Incomplete input if a fourth band is expected |
| 5-band | Band 5 | Do not treat band 5 as a multiplier |
| 6-band | Band 5 | Band 6 is TCR, not tolerance |
Do not confuse tolerance with rating
Tolerance does not tell you the power rating, maximum voltage, pulse capability, noise, or long-term stability. A 1 kohm resistor at five percent can still be the wrong part if the circuit needs a one-watt body, a flameproof construction, or a low temperature coefficient. TCR describes temperature drift, while meter accuracy describes the measurement system. Match the value and tolerance to the complete specification.
Worked range examples
| Nominal value | Tolerance | Deviation | Allowed range |
|---|---|---|---|
| 1 kohm | +/- 1% | 10 ohms | 990 to 1,010 ohms |
| 1 kohm | +/- 2% | 20 ohms | 980 to 1,020 ohms |
| 1 kohm | +/- 5% | 50 ohms | 950 to 1,050 ohms |
| 1 kohm | +/- 10% | 100 ohms | 900 to 1,100 ohms |
| 4.7 kohm | +/- 5% | 235 ohms | 4,465 to 4,935 ohms |
| 220 ohms | +/- 10% | 22 ohms | 198 to 242 ohms |
| 100 ohms | +/- 0.5% | 0.5 ohm | 99.5 to 100.5 ohms |
| 0.22 ohm | +/- 20% | 0.044 ohm | 0.176 to 0.264 ohm |
Use deviation = nominal x tolerance / 100, then subtract and add the deviation to the nominal value. A range check tells you whether a reading is plausible; it does not prove the resistor is healthy.
When a reading is outside the range
First confirm that the resistor was measured without power and with at least one lead isolated when parallel paths are possible. Check the meter range and probe resistance, allow the part to return to a stable temperature, and inspect for heat damage. If the isolated value remains outside the expected range, treat the component as drifted or failed and use the equipment service information rather than guessing a replacement.
Frequently asked questions
Is +/- 1% always better than +/- 5%?
It is tighter, but it may not be needed for the circuit and does not replace power, voltage, pulse, or construction requirements.
Does tolerance include temperature drift?
No. Initial tolerance and TCR are separate specifications. Temperature, aging, and overload can add later changes.
What does a gold band mean?
Gold is x0.1 in the multiplier position and commonly +/- 5% in the tolerance position.
Can I choose a replacement from the tolerance band alone?
No. Confirm the full part specification and the circuit requirement.
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
4-Band Resistor Color Code shows where tolerance sits; 3-Band vs 4-Band explains the missing-band convention; TCR covers temperature drift; and Multimeter Verification covers measurement limits.