Standard Resistor Values: E6 to E192

What “Standard” or “Preferred” Values Actually Are

Every resistor sold off the shelf comes from a short list of values that repeats identically in every decade, no matter the manufacturer. That list is not arbitrary — it is the IEC 60063 standard for preferred numbers, and it exists because manufacturing, testing, and stocking a distinct part for every conceivable resistance would be enormously wasteful. A resistor production line instead targets only the values in its chosen series, and parts that measure slightly outside their assigned band get sorted, or “binned,” into whichever tolerance grade they actually fall into.

This restriction benefits everyone, not just the manufacturer. A designer who needs “about 4.7 kΩ” can search a few dozen catalog values per decade instead of thousands, a distributor can stock a manageable number of SKUs while still covering the full resistance range, and the tolerance grade sold at each value is already accounted for in how densely that series is spaced. The tables further down this page are the actual base-decade values behind every E-series resistor you can buy — the same values the E-Series Finder searches when it looks for a match to your target.

The E-Series System: Numbering and Its Historical Tolerance Link

The “E” in E6, E12, E24, and so on is the IEC 60063 series designation; the number that follows is approximately how many values fill one decade — the span from 1.0 up to 10. E6 packs 6 values into that span, E12 packs 12, E24 packs 24, and the progression continues through E48, E96, and E192, with each series roughly doubling the previous one's value count. More values per decade means a smaller percentage gap between neighbors, so the tables get visibly denser as the E-number rises.

Historically, each series was sized to match a specific tolerance grade: E6 for ±20% parts, E12 for ±10%, E24 for ±5%, E48 for ±2%, E96 for ±1%, and E192 for ±0.5%. The logic is straightforward — at ±20% tolerance, adjacent values in a 6-value decade already overlap at their edges, so a finer series would add steps without adding real coverage; at ±0.5% tolerance, only a 192-value decade keeps neighboring tolerance bands from overlapping at all.

That pairing is a historical convention, though, not a rule any modern manufacturer enforces. It is entirely normal today to buy an E96 or E192 value at ±1%, ±0.5%, ±0.1%, or tighter, and just as normal to buy a coarse E24 value at a tight tolerance when cost matters more than value resolution. Treat the tolerance figures above as the reason each series has the value count it does, not as a spec you can read off a part's series alone — always check the resistor's actual tolerance band or datasheet.

The Base-Decade Reference Tables (E6 to E192)

Each table below lists a series' complete base decade — every standard value from 1.00 to 9.99, in ascending order. These are the exact figures defined by IEC 60063, not rounded approximations, so they match any catalog or datasheet you compare them against.

Scaling a Base Value to Any Decade

The tables above only cover the 1.00–9.99 decade, but that single decade is all a manufacturer needs to publish — every other decade is the same set of digits with the decimal point, and the unit prefix, moved. To reach a different decade, multiply the base value by the matching power of ten: the E24 base value 4.7 becomes 47 Ω one decade up, 470 Ω the decade after that, then 4.7 kΩ, 47 kΩ, 470 kΩ, and 4.7 MΩ as the multiplier keeps climbing. The digits “4.7” never change; only where the decimal point and unit symbol land does.

This is why the same 24, 96, or 192 numbers you see in the tables above reappear, unit prefix aside, at every resistance range from single-digit ohms up into the megaohms. A catalog or a search tool does not need — and does not store — a separate table per decade; it stores the base decade once and multiplies by the requested power of ten.

Choosing the Right Series for a Design

Match the series to the tolerance the design actually needs, and no tighter. E12 or E24 covers the overwhelming majority of general-purpose work — pull-ups, current-limiting resistors, indicator circuits — where a few percent of error has no visible effect. E96 is the common choice once a circuit needs 1% precision, such as an op-amp gain-setting network or a moderately precise divider. E192 is worth reaching for only on tight references, calibration-grade dividers, or measurement circuits where every fraction of a percent of error matters.

Jumping straight to E96 or E192 “to be safe” when E24 would meet spec adds cost and inventory complexity without a real benefit — finer series parts cost more per unit and add more distinct values to a bill of materials. If you already know the target resistance and just need the closest standard value or combination that hits it, the E-Series Finder searches these exact tables for you across whichever series and combination size you choose.

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Frequently Asked Questions

What are "standard" or "preferred" resistor values?

They are the fixed set of resistances that manufacturers actually produce and stock, defined by IEC 60063. Rather than making parts at every possible value, the industry agreed on a small, logarithmically spaced list per decade — E6, E12, E24, E48, E96, or E192 — so that any resistance a designer needs is within a known maximum percentage of an available part.

Why don't resistors come in round numbers like 100 Ω, 200 Ω, 300 Ω?

Evenly spaced values waste coverage: the percentage gap between 100 Ω and 200 Ω is enormous, while the gap between 900 Ω and 1000 Ω is tiny. Preferred numbers are spaced so every step is roughly the same percentage from the last, giving even error coverage across the whole decade with the fewest distinct parts — which is why the values look irregular, like 4.7, 5.6, and 6.8, instead of round.

What do the numbers in E6, E12, E24, E48, E96, and E192 mean?

The number after the E is approximately how many standard values fill one decade (1 to 10). E6 has 6 values per decade, E12 has 12, and so on up to E192. Each step up roughly doubles the value count, halving the average percentage gap between neighboring values.

Does the E-series a resistor belongs to determine its tolerance?

Historically, yes — E6 was built for ±20% parts, E12 for ±10%, E24 for ±5%, E48 for ±2%, E96 for ±1%, and E192 for ±0.5%, because a series only needs enough steps to keep adjacent values from overlapping at that tolerance. In practice today, manufacturers sell resistors at any of these series' values across a range of tolerances, so the series a value belongs to is no longer a reliable guide to the tolerance of a specific part — check the part's datasheet or tolerance band instead.

How do I get a value like 47 kΩ or 220 Ω from these tables?

Every table below lists only the base decade, 1.00 to 9.99. To reach any other decade, multiply every base value by the same power of ten: the E24 value 4.7 becomes 47 Ω, 470 Ω, 4.7 kΩ, 47 kΩ, 470 kΩ, or 4.7 MΩ depending on which power of ten you multiply by. The set of digits never changes — only the decimal point and unit prefix move.

Which E-series should I actually use in a design?

Match the series to the tolerance the design needs and no tighter: E12 or E24 covers most general-purpose work, E96 is the common choice for 1% precision circuits like op-amp gain-setting networks, and E192 is reserved for tight references and calibration-grade dividers. Finer series cost more per part and add more distinct SKUs to a bill of materials, so jumping to E96 or E192 when E24 would meet spec only adds cost and inventory complexity without benefit.