RESISTOR COLOUR CODE

the bands, the tolerances and the preferred series of two standards

Built as a memo rather than a table: the thing worth hanging it up for reads across the room, with the full reference in smaller type below it.

Three sizes in one archive — from a sheet on the fridge to a poster on the wall.

Formats: A4 · A3 · A2
What you get: Print-ready PDFs, one per size, with every letterform converted to outlines — nothing to install, nothing to shift.
Subject: science · beginners · reference · study

The bands are read from the end they sit closer to; the wider band is the tolerance. The values here are calculated from Table 1 of IEC 60062:2016, the preferred series from Table 1 of IEC 60063:2015.

THE VALUES ARE NOT ROUND BECAUSE THEY ARE STEPS, NOT NUMBERS

The E24 series is a geometric ladder: 24 steps to a decade, each about a tenth larger than the one before. That is why it holds 47 and 68 rather than 50 and 70.

The step is matched to the tolerance so that the ranges of neighbouring values do not overlap too far. In E6 at ±20 % the fit is exact: 10 and 15 meet at 12, 22 and 33 meet at 26.4, and six values cover the decade edge to edge. In the finer series, rounding to two figures leaves the ladder uneven: E24 at ±5 % leaves seven narrow holes, the widest between 13.65 and 14.25. A resistance that falls there is inside no neighbour tolerance at all.

And eight values of the series do not follow the formula at all: 27, 30, 33, 36, 39, 43, 47, 82. The standard does not hide it. A note records that the series came out of commercial practice before the first edition of 1952, and that correcting it has never seemed appropriate.

On the sheet

The bands are read from the end they sit closer to; the wider band is the tolerance. The values here are calculated from Table 1 of IEC 60062:2016, the preferred series from Table 1 of IEC 60063:2015.
Colour carries meaning, but meaning never rests on colour alone — the sheet reads in black and white.
Nothing about how it was made: the sheet carries only what the reader needs.

Printing

Three sizes in the archive: A4 — 210×297 mm, A3 — 297×420 mm, A2 — 420×594 mm.
All text is converted to outlines. No fonts to install, and nothing shifts on another machine.
White background and sparing fills — it prints on a home printer without draining the cartridge.
Margins of at least 10 mm: a home printer cannot print to the edge.
No stroke thinner than 0.3 mm, so nothing disappears in print.

Why the numbers can be trusted. Every countable number here is computed from data rather than typed in, and the sheet must pass 14 independent checks before it is allowed to build — how many items there are, the order they come in, and the claim in the highlighted box itself. If one fails, there is no file.

RESISTOR COLOUR CODE

THE VALUES ARE NOT ROUND BECAUSE THEY ARE STEPS, NOT NUMBERS

On the sheet

Printing

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