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Electronics / LOCAL TOOL

Resistor Code Calculator

Decode and encode resistor colour bands and common SMD markings.

Runs locally — input is never uploaded
Colours, SMD marking, or resistance

Colour names go in band order. A resistance encodes back to bands; tolerance and band count are optional and default to 5% and four bands.

ResultReady when you are

WHAT IT DOES

Read the bands or turn a value back into them.

Decode 4-, 5-, and 6-band resistor colours, conventional 3/4-digit SMD markings, R-decimal codes, and EIA-96 codes. Enter a resistance with a tolerance and band count to produce the corresponding colour sequence.

Why use it?

Use it to decode a resistor marking or work out the bands for a target resistance, while making the marking scheme explicit.

How to use this tool

  1. Enter color names in band order, an SMD marking, or a resistance with optional tolerance and band count.
  2. For example, yellow violet red gold represents 4.7 kΩ at 5% tolerance; 472 is a conventional SMD code for 4.7 kΩ.
  3. Review any rounding when encoding bands and verify unfamiliar alphanumeric markings against the component's datasheet. A similar-looking manufacturer code may use a different scheme.

Details and limitations

  • Colour positions, multipliers, tolerances, and six-band temperature coefficients follow IEC 60062 and the cited Vishay component-marking tables verified on 30 August 2026.
  • Encoding rounds to the nearest value the chosen number of significant bands can represent and states when it did so.
  • EIA-96 is decoded as a preferred-value index plus multiplier. Manufacturer-specific alphanumeric markings can use other schemes and must be checked against the part datasheet.

WORKED EXAMPLES

Read significant bands, multiplier, and tolerance

Calculate the four-band sequence below. Yellow and violet give 47, red multiplies by 100, and gold states the tolerance rather than another digit.

Color sequence

yellow violet red gold

Expected result

4.7 kΩ with 5% tolerance. The conventional SMD marking 472 represents the same nominal resistance but does not itself encode the gold band's tolerance.

COMMON QUESTIONS

Resistor Codes questions

Which direction should I read resistor bands?
The tolerance band is normally spaced farther from the value bands and is read last. If spacing is ambiguous, compare the result with the expected circuit range or measure the isolated component.
Does every SMD resistor use these markings?
No. Small parts may be unmarked, and manufacturers also use proprietary codes. The tool covers conventional digit, R-decimal, zero-link, and EIA-96 forms.