Standard Resistor Values (E-Series)

IEC 60063 defines preferred values so that each series covers a decade with steps roughly equal to its tolerance: E6 (±20 %) has six values per decade, E12 twelve, E24 twenty-four, E48, E96 and E192 forty-eight, ninety-six and one hundred and ninety-two. Any value you type is read with SI prefixes (4.7k, 4k7, 2M2, 470R, 0.33), then compared with the series values scaled to its decade and the neighbouring ones; the nearest by ratio, the neighbours below and above, and the error in percent are reported for every series.

The values are nominally 10^(k/N) rounded, but the published lists differ from that in a few places — 3.01 (not 3.02) in E96, 9.20 (not 9.19) in E192, and E24 keeps historical values such as 2.7, 3.3, 4.7 rather than the rounded powers. The page stores the E24 and E192 lists as printed and derives E6/E12 and E48/E96 as every fourth or second entry, which is how the standard defines them. The same values apply to capacitors and inductors sold in E-series.

When no single value is close enough, the page searches every pair from your series: two values below the target in series (sum) and two above it in parallel (product over sum), over the surrounding decades, keeping the smallest error. Two parts add their tolerances, so a single part from a tighter series is usually the better buy where one exists; the pairs are for what you have in the drawer. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.