Translate bands into resistance values instantly
Supports 4-band, 5-band, and 6-band resistor colour codes. See the nominal resistance, tolerance, and temperature coefficient (for 6-band) as you pick colours, plus the closest preferred E-series values. The reverse lookup mode suggests colour bands from a target resistance.
- 1Bidirectional colour ↔ value solver with live updates
- 2Shareable URLs and local favourites for frequent combos
- 3Nearest E24 / E96 picks for procurement-friendly values
- 4Touch-friendly swatch UI tuned for phones and tablets
How to use (3 steps)
- Choose “Colours → Value” or “Value → Colours” from the tabs above.
- Select the band count and each band colour, or enter a target resistance, tolerance, and tempco.
- Check the result, then copy the URL or save as a favourite if you want to reuse the same setup.
All calculations run only in your browser and your input values are not sent to any server.
This result shows the nominal resistance and tolerance range derived from the selected band colours.
This result is an example of a colour code close to your target value and is meant as a guide when choosing components.
Reference table
Not every colour is valid for every band. Temperature coefficients apply to precision 6-band resistors.
| Colour | Digit | Multiplier | Tolerance | Temp. coefficient |
|---|---|---|---|---|
| Black | 0 | ×100 | — | 250 ppm/K |
| Brown | 1 | ×101 | ±1% | 100 ppm/K |
| Red | 2 | ×102 | ±2% | 50 ppm/K |
| Orange | 3 | ×103 | ±3% | 15 ppm/K |
| Yellow | 4 | ×104 | ±4% | 25 ppm/K |
| Green | 5 | ×105 | ±0.5% | 20 ppm/K |
| Blue | 6 | ×106 | ±0.25% | 10 ppm/K |
| Violet | 7 | ×107 | ±0.1% | 5 ppm/K |
| Gray | 8 | ×108 | ±0.05% | 1 ppm/K |
| White | 9 | ×109 | — | 0.5 ppm/K |
| Gold | — | ×10-1 | ±5% | — |
| Silver | — | ×10-2 | ±10% | — |
| None | — | — | ±20% | — |
How to use this calculator effectively
This guide helps you use Resistor Color Code Calculator in a repeatable way: define a baseline, change one variable at a time, and explain each output using explicit assumptions before sharing results.
How it works
The calculator applies deterministic formulas to your input values and only rounds at the final display layer. This makes it useful for comparative analysis: keep one scenario as a baseline, then vary assumptions and measure the delta in both absolute terms and percentage terms. If a change appears too large or too small, verify units, period conventions, and sign direction before interpreting the result.
When to use
Use this page when you need a fast planning estimate, a classroom check, or a reproducible scenario that teammates can review. It is most effective at the decision-prep stage, where you need to compare options quickly and decide which assumptions deserve deeper modeling or external validation.
Common mistakes to avoid
- Mixing units such as percent vs decimal, or monthly vs yearly settings.
- Changing multiple fields at once, which hides the real cause of result movement.
- Comparing outputs across tools without aligning constants and default conventions.
- Treating rounded display values as exact inputs for downstream calculations.
Interpretation and worked example
Start with a baseline case and save that output. Next, edit one assumption to reflect your realistic alternative, then compare both the direction and size of change. If the direction matches domain intuition and magnitude is plausible, your setup is likely coherent. If not, check hidden defaults, unit conversions, boundary conditions, and date logic before drawing conclusions.
See also
FAQ
Which band count should I choose?
Standard carbon film resistors are 4-band, metal film parts typically use 5 bands, and precision parts with thermal tracking add a 6th temperature coefficient band.
Can I derive colours from a value?
Yes. Use the “Value → Colours” tab, enter your value and tolerance, then submit to get a suggested colour code.
What are the E-series suggestions?
They show the nearest IEC preferred values (E24/E96) so you can match against commonly stocked resistors.
What should I enter first?
Start with the minimum required inputs shown above the calculate button, then keep optional settings at their defaults for a first pass. After getting a baseline, change one parameter at a time so you can explain which assumption moved the output.
How precise are the results?
The calculator keeps internal precision and rounds only for display. Small differences can still appear if another tool uses different constants, period conventions, or rounding rules. Align assumptions before comparing final values.
How it’s calculated
- 4/5‑band codes use significant digits, a multiplier band, and a tolerance band (6‑band adds a tempco band).
- Nominal resistance = significant digits × multiplier; tolerance is applied as a ±% range.
- The shareable URL keeps your band colours and mode so you can reopen the same configuration later.
Comments
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