Resistor Colour Code Widget

Add a resistor colour code decoder to your website. Visitors pick the band colours on a 4, 5 or 6-band resistor to read its value, tolerance and temperature coefficient, or type a value such as 4k7 to see which bands to look for.

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Exactly what your visitors will see

Under the widget on your page: Resistor Colour Code by A2Z Tools

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<div data-a2z-widget="resistor-color-code" data-height="640"></div>
<p class="a2z-attribution" style="margin:6px 0 0;font:12px/1.4 system-ui,sans-serif;opacity:.8">Resistor Colour Code by <a href="https://a2z.tools/resistor-color-code-calculator" target="_blank" rel="nofollow noopener">A2Z Tools</a></p>
<script async src="https://a2z.tools/embed.js"></script>

Recommended. A small script (what it does) sizes the widget to fit its content, loads it lazily and keeps it isolated in its own frame. Works in WordPress (Custom HTML block), Squarespace, Webflow, Shopify, Blogger, React / Next.js and plain HTML - anywhere a <script> tag is allowed.

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How it works

The widget uses the colour table of IEC 60062:2016 (Table 1) through the A2Z Resistor Colour Code Calculator's engine. On a 4-band resistor the first two bands are digits, the third a multiplier and the fourth the tolerance; 5 and 6-band resistors carry three digits, and the sixth band is the temperature coefficient. A drawing shows the bands, but every colour is also named in text and in the result, so the widget works for colour-blind visitors. The result includes the minimum and maximum resistance the tolerance allows. In value mode it rounds to the digits the chosen band count can carry and says when it had to.

Method

  • Value = digits x multiplier (IEC 60062 Table 1)
  • Digits: black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, grey 8, white 9
  • Multiplier: silver x0.01, gold x0.1, black x1, brown x10 ... white x10^9
  • Tolerance: brown 1%, red 2%, orange 0.05%, yellow 0.02%, green 0.5%, blue 0.25%, violet 0.1%, grey 0.01%, gold 5%, silver 10%, no band 20%
  • Temperature coefficient (ppm/K): black 250, brown 100, red 50, orange 15, yellow 25, green 20, blue 10, violet 5, grey 1; range = value x (1 -/+ tolerance)

Worked examples

Common 4-band part

Inputs: Yellow, violet, red, gold

Result: 4.7 kohm +/-5%, anywhere from 4.465 to 4.935 kohm

4, 7, x100, gold = 5%.

Precision 6-band part

Inputs: Brown, black, black, red, brown, red

Result: 10 kohm +/-1%, 50 ppm/K

1, 0, 0, x100, brown = 1%, red TCR = 50 ppm/K.

Limitations

  • The pink (x0.001) multiplier in IEC 60062 is not offered, and 3-band parts are read as +/-20% without a tolerance band.
  • Printed colours fade and vary between makers; the widget cannot see the part, so brown/red/orange confusions are the reader's to resolve with a meter.
  • Covers the colour code only - not SMD numeric or EIA-96 codes.

Where publishers use it

  • Electronics kits and component shops helping buyers identify parts
  • Beginner soldering and repair guides
  • School physics and technology lessons
  • Maker-space and hackerspace wikis

Questions

Which end do I start reading from?

The end the bands are crowded towards. IEC 60062 asks for the first band nearest the end and for the tolerance band to be at least 1.5 times wider than the others, which helps tell the ends apart.

What does a 6th band mean?

It is the temperature coefficient in ppm per kelvin - how much the resistance changes per degree. Under IEC 60062 brown is 100 ppm/K, red 50, yellow 25 and black 250.

Why was my value rounded?

A 4-band resistor carries only two significant digits (4.7k, not 4.75k). Choose 5 bands for three digits.

Can I link to a specific colour code?

Yes. The embed code can preset the bands, for example ?v_bands=brown,black,red,gold.

Sources

  1. IEC 60062:2016+AMD1:2019 Marking codes for resistors and capacitors (Table 1, code colour prescriptions) - International Electrotechnical Commission . Digits, multipliers, tolerances and TCR per colour

Cite or recommend this tool

If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.

A2Z Tools Resistor Colour Code
https://a2z.tools/resistor-color-code-calculator

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