Calculators · Component ID
Resistor value decoder
LiveDecode colour bands and SMD resistor markings into resistance values.
Turn resistor markings into values before they go into the circuit.
Inputs
Build the tool
Examples: 472, 1001, 4R7, 01C. EIA-96 codes use two digits and a letter.
Live visual
Calculation cue
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Enter valid values to show the live visual.
Result
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Enter valid values to calculate.
Result detail
Results appear here once the inputs are valid.
Calculator guide
Resistor value decoder formulas and practical checks
Formulas, examples, and practical notes for using the result with confidence.
Overview
Resistor bands are a tiny rainbow number system, while SMD markings squeeze the same idea onto a speck of a component. Once you know which end to start from, both codes become much less mysterious.
Use this resistor colour code and SMD decoder to identify 4-band, 5-band, 6-band, and marked chip resistors before they reach the breadboard. For old, heat-damaged, or critical parts, let a multimeter have the final word.
Current example
Enter valid values above and this example will update with the calculator state.
Read the resistor from left to right
Colour bands encode significant digits, multiplier, tolerance, and sometimes tempco.
A 4-band resistor uses two significant digits, one multiplier, and one tolerance band. A 5-band resistor uses three significant digits, then multiplier and tolerance.
A 6-band resistor adds a temperature coefficient band. The calculator focuses on resistance and tolerance; tempco still belongs in the part selection notes.
The tolerance band is often spaced farther from the others and commonly gold, silver, brown, or red. Put that band on the right before decoding the digits.
Decode the tiny printing on SMD parts
Chip resistors use compact printed codes instead of colour bands.
Three-digit SMD codes use two significant digits and a multiplier. Four-digit codes use three significant digits and a multiplier.
R notation places the decimal point in the code, such as 4R7 for 4.7 Ω. EIA-96 codes use two numbers plus a multiplier letter for 1% resistor families.
Three-digit SMD code
A few markings you will meet often
Common markings become easier once you read the digits and multiplier separately.
Yellow, violet, red, gold is 47 × 100 Ω, or 4.7 kΩ with ±5% tolerance.
The SMD code 472 is 47 × 100 Ω, also 4.7 kΩ. The code 1001 is 100 × 10 Ω, or 1 kΩ.
Four-band
Yellow, violet, red, gold = 47 × 100 Ω = 4.7 kΩ ±5%.
SMD decimal
4R7 uses R as the decimal point, so the part is 4.7 Ω.
Useful moments at the bench
Decoding is useful at the bench, in repairs, and when sorting loose parts.
Use the decoder to identify through-hole resistors in a kit, confirm SMD markings on a board, or sort loose resistors before populating a prototype.
For production work, rely on labelled reels, purchasing records, and measurement rather than visual decoding alone.
Kit building
Check resistor values before soldering.
Repair
Read markings from an existing board when the schematic is unavailable.
Parts sorting
Turn mixed loose resistors into labelled storage.
When the colours play tricks
Orientation, lighting, and colour similarity can easily produce a wrong value.
Brown, red, orange, and gold can be hard to distinguish on old parts or under warm lighting. Blue, violet, grey, and faded black can also be ambiguous.
When the value matters, measure the part with a meter and remember that in-circuit measurements can be affected by parallel paths.
Assumptions and limits
- Results are design estimates, not a substitute for datasheets, measurements, safety approvals, or engineering review.
- Component tolerance, temperature, supply variation, and real loading can move the final circuit away from the ideal calculation.
- Calculator results are estimates for design and learning. Verify values against datasheets, tolerances, temperature, load behaviour, and safety requirements before using them in a real circuit.
Licensing
Calculator copy, equations, and generated visuals are provided for learning and design-reference use on Kobee unless a specific licence is shown.
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