E-Series Value Calculator

A set of standard "preferred" component values spread logarithmically across each decade, so that with a given tolerance the values cover the whole range without large gaps.

Because tolerance already blurs the exact value. A ±5% resistor covers a range, so only ~24 values per decade (E24) are needed to reach any value within tolerance.

Each value is approximately 10^(k/N) for k = 0…N−1 in a decade, where N is the series number (12, 24, 96…), then rounded to standard printed values.

E6 = ±20%, E12 = ±10%, E24 = ±5%, E48 = ±2%, E96 = ±1%, and E192 = ±0.5% or better.

Pick the nearest, or use a denser series (higher E number), or combine two resistors in series or parallel to get closer — the second tab does this.

Yes — capacitors, inductors, and Zener voltages all use the same preferred-value system, usually E6 or E12 for capacitors.

Combine two standard resistors: in series their values add, in parallel they combine as R1×R2/(R1+R2). This lets you reach almost any target precisely.

Series makes a larger value than either resistor; parallel makes a smaller one. Choose whichever brackets your target, and the calculator finds the closest pair.

How far the standard (or combined) value is from your target, as a percent. Compare it to the resistor tolerance to judge if it matters.

Not necessarily — tighter series (E96/E192) cost more and may be harder to source. Use the loosest series that meets your accuracy need.

Not exactly — the rounding differs slightly, so some E24 values (like 3.3) differ a little from the nearest E96 value. Each series is defined on its own.

Exact odd values may not exist, may be costly, or may have long lead times. Two common resistors are cheap, in stock, and can be more accurate together.