E series of preferred numbers

Not to be confused with E notation or E number.

This graph shows how almost any value between 1 and 10 is within ±10% of an E12 series value, and its difference from the ideal value in a geometric sequence

Two decades of E12 values, which would give resistor values of 1 Ω to 82 Ω

The E series is a system of preferred numbers (also called preferred values) derived for use in electronic components. It consists of the E3, E6, E12, E24, E48, E96 and E192 series,<ref name="Walsin_2018_E1"/> where the number after the 'E' designates the quantity of logarithmic value "steps" per decade. Although it is theoretically possible to produce components of any value, in practice the need for inventory simplification has led the industry to settle on the E series for resistors, capacitors, inductors, and zener diodes. Other types of electrical components are either specified by the Renard series (for example fuses) or are defined in relevant product standards (for example IEC 60228 for wires).

History

During the Golden Age of Radio (1920s to 1950s), numerous companies manufactured AM radio receivers for consumer use. In the early years, many components were not standardized between radio manufacturers. The capacitance values of capacitors (previously called condensers)<ref name="AlliedRadio_1930_1"/><ref name="RadioShack_1940_1"/> and resistance values of resistors<ref name="AlliedRadio_1930_2"/><ref name="RadioShack_1940_2"/><ref name="FTRC_1943"/><ref name="FTRC_1946"/> were not standardized.<ref name="Jameco_2017"/>

In 1924, the Radio Manufacturers Association (RMA) was formed in Chicago, Illinois by 50 radio manufacturers to license and share patents. Over time, this group created some of the earliest standards for electronics components. In 1936, the RMA adopted a preferred number system for the resistance values of fixed composition resistors.<ref name="Blackburn_1949"/> Over time, resistor manufacturers migrated from older values to the 1936 resistance value standard.<ref name="FTRC_1943"/><ref name="FTRC_1946"/>

During World War II (1940s), American and British military production was a major influence for establishing common standards across many industries, especially in electronics, where it was essential to produce large quantities of standardized electronic parts for military wireless communication and Radar devices. Later, the mid-20th century baby boom and the invention of the transistor kicked off demand for consumer electronics goods during the 1950s. As transistor radio production migrated from United States towards Japan during the late-1950s, it was critical for the electronic industry to have international standards.

As worked on by the RMA,<ref name="Dyck_1951"/> the International Electrotechnical Commission (IEC) began work on an international standard in 1948.<ref name="IEC_60063_1963"/> The first version of this IEC Publication 63 (IEC 63) was released in 1952.<ref name="IEC_60063_1952"/> Later, IEC 63 was revised, amended, and renamed into the current version known as IEC 60063:2015.<ref name="IEC_60063_2015"/>

IEC 60063 release history:

• IEC 63:1952 (aka IEC 60063:1952), first edition, published 1952-01-01.<ref name="IEC_60063_1952"/>
• IEC 63:1963 (aka IEC 60063:1963), second edition, published 1963-01-01.<ref name="IEC_60063_1963"/>
• IEC 63:1967/AMD1:1967 (aka IEC 60063:1967/AMD1:1967), first amendment of second edition, published 1967.<ref name="IEC_60063_1963"/>
• IEC 63:1977/AMD2:1977 (aka IEC 60063:1977/AMD2:1977), second amendment of second edition, published 1977.<ref name="IEC_60063_1963"/>
• IEC 60063:2015, third edition, published 2015-03-27.<ref name="IEC_60063_2015"/>

Overview

The E series of preferred numbers was chosen such that when a component is manufactured it will end up in a range of roughly equally spaced values (geometric progression) on a logarithmic scale. Each E series subdivides each decade magnitude into steps of 3, 6, 12, 24, 48, 96, 192 values.<ref group="nb" name="NB_E1"/> Subdivisions of E3 to E192 ensure the maximum error will be divided in the order of 40%, 20%, 10%, 5%, 2%, 1%, 0.5%. Also, the E192 series is used for 0.25% and 0.1% tolerance resistors.

Historically, the E series is split into two major groupings:

• E3, E6, E12, E24 are subsets of E24. Values in this group are rounded to 2 significant figures.
• E48, E96, E192 are subsets of E192. Values in this group are rounded to 3 significant figures.

Formula

The formula for each value is determined by the m-th root, though eight of the official E24 values and one of the official E192 values do not match the following formula.

<math display=block>V_n = \mathrm{round} (\sqrt[m]{10^n})</math>

where <math>V_n</math> is the rounded value, <math>m</math> is an integer of the E series group size, and <math>n</math> is an integer of <math>\{0, 1, 2, ..., m-1\} .</math>

E24 subsets

Since the electronic component industry established component values before standards discussions in the late-1940s, the standards organizations decided that it wasn't practical to change the former established values. These older values were used to create the E6, E12, E24 series standard that was accepted in Paris in 1950 then published as IEC 63 in 1952.

For E3 to E24, the values from the formula are rounded to 2 significant figures. For unknown historical reasons, eight older industry values (shown in bold) are different from the calculated values.

Comparison of rounded log-scaled values to de-facto standard of E24 series

<math>n</math>	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23
Calculated <math>V_n</math> values	1.0	1.1	1.2	1.3	1.5	1.6	1.8	2.0	2.2	2.4	2.6	2.9	3.2	3.5	3.8	4.2	4.6	5.1	5.6	6.2	6.8	7.5	8.3	9.1
Official E24 values	1.0	1.1	1.2	1.3	1.5	1.6	1.8	2.0	2.2	2.4	2.7	3.0	3.3	3.6	3.9	4.3	4.7	5.1	5.6	6.2	6.8	7.5	8.2	9.1

E192 subsets

For E48 to E192, the values from the formula are rounded to 3 significant figures. Consequently, the eight exceptional E24 series values shown in bold above do not exist in the E48, E96, E192 series. The E48 and E96 series follow the formula, as does E192 series but with one exception:

• To calculate the E48 series: <math>m</math> is 48, then <math>n</math> is incremented from 0 to 47 through the formula.
• To calculate the E96 series: <math>m</math> is 96, then <math>n</math> is incremented from 0 to 95 through the formula.
• To calculate the E192 series: <math>m</math> is 192, then <math>n</math> is incremented from 0 to 191 through the formula, with one exception for <math>n=185</math> where 9.20 is the official value instead of the calculated 9.19 value.

Exceptions

High tolerance families

The E3 series is rarely used,<ref group="nb" name="NB_E1"/> except for some components with high variations like electrolytic capacitors, where the given tolerance is often unbalanced between negative and positive such as ^+50%
_−30% or ^+80%
_−20%, or for components with uncritical values such as pull-up resistors. The calculated constant tangential tolerance for this series gives (³√10 − 1) ÷ (³√10 + 1) = 36.60%, approximately. While the standard only specifies a tolerance greater than 20%, other sources indicate 40% or 50%. Currently, most electrolytic capacitors are manufactured with values in the E6 or E12 series, thus E3 series is mostly obsolete.

Low tolerance families

Since some values of the E24 series do not exist in the E48 / E96 / E192 series, some resistor manufacturers have added missing E24 values into some of their 1%, 0.5%, 0.25%, 0.1% tolerance resistor families. This allows easier purchasing migration between various tolerances. This E series merging is noted on resistor datasheets and webpages as "E96 + E24" or "E192 + E24".<ref name="Bourns_2017"/><ref name="Vishay_2017_Thick"/><ref name="Vishay_2017_Thin"/>

Comparison of E24 vs. E48 values

Both E24 & E48 contains – 1.00, 1.10, 7.50

E48 is missing – 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.20, 2.40, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10

Comparison of E24 vs. E96 values

Both E24 & E96 contains – 1.00, 1.10, 1.30, 1.50, 2.00, 7.50

E96 is missing – 1.20, 1.60, 1.80, 2.20, 2.40, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 4.70, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10.

Comparison of E24 vs. E192 values

Both E24 & E192 contains – 1.00, 1.10, 1.20, 1.30, 1.50, 1.60, 1.80, 2.00, 2.40, 4.70, 7.50

E192 is missing – 2.20, 2.70, 3.00, 3.30, 3.60, 3.90, 4.30, 5.10, 5.60, 6.20, 6.80, 8.20, 9.10

Examples

If a manufacturer sold resistors with all values in a range of 1 ohm to 10 megaohms, the available resistance values for E3 through E12 would be:

E3 (in ohms)	E6 (in ohms)	E12 (in ohms)
1.0, 2.2, 4.7, 10, 22, 47, 100, 220, 470, 1 k, 2.2 k, 4.7 k, 10 k, 22 k, 47 k, 100 k, 220 k, 470 k, 1 M, 2.2 M, 4.7 M, 10 M	1.0, 1.5, 2.2, 3.3, 4.7, 6.8, 10, 15, 22, 33, 47, 68, 100, 150, 220, 330, 470, 680, 1 k, 1.5 k, 2.2 k, 3.3 k, 4.7 k, 6.8 k, 10 k, 15 k, 22 k, 33 k, 47 k, 68 k, 100 k, 150 k, 220 k, 330 k, 470 k, 680 k, 1 M, 1.5 M, 2.2 M, 3.3 M, 4.7 M, 6.8 M, 10 M	1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2, 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82, 100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820, 1 k, 1.2 k, 1.5 k, 1.8 k, 2.2 k, 2.7 k, 3.3 k, 3.9 k, 4.7 k, 5.6 k, 6.8 k, 8.2 k, 10 k, 12 k, 15 k, 18 k, 22 k, 27 k, 33 k, 39 k, 47 k, 56 k, 68 k, 82 k, 100 k, 120 k, 150 k, 180 k, 220 k, 270 k, 330 k, 390 k, 470 k, 560 k, 680 k, 820 k, 1 M, 1.2 M, 1.5 M, 1.8 M, 2.2 M, 2.7 M, 3.3 M, 3.9 M, 4.7 M, 5.6 M, 6.8 M, 8.2 M, 10 M

If a manufacturer sold capacitors with all values in a range of 1 pF to 10,000 μF, the available capacitance values for E3 and E6 would be:

E3

E6

1.0 pF, 2.2 pF, 4.7 pF, 10 pF, 22 pF, 47 pF, 100 pF, 220 pF, 470 pF, 1 nF, 2.2 nF, 4.7 nF, 10 nF, 22 nF, 47 nF, 100 nF, 220 nF, 470 nF, 1 μF, 2.2 μF, 4.7 μF, 10 μF, 22 μF, 47 μF, 100 μF, 220 μF, 470 μF, 1000 μF, 2200 μF, 4700 μF, 10000 μF

1.0 pF, 1.5 pF, 2.2 pF, 3.3 pF, 4.7 pF, 6.8 pF, 10 pF, 15 pF, 22 pF, 33 pF, 47 pF, 68 pF, 100 pF, 150 pF, 220 pF, 330 pF, 470 pF, 680 pF, 1 nF, 1.5 nF, 2.2 nF, 3.3 nF, 4.7 nF, 6.8 nF, 10 nF, 15 nF, 22 nF, 33 nF, 47 nF, 68 nF, 100 nF, 150 nF, 220 nF, 330 nF, 470 nF, 680 nF, 1 μF, 1.5 μF, 2.2 μF, 3.3 μF, 4.7 μF, 6.8 μF, 10 μF, 15 μF, 22 μF, 33 μF, 47 μF, 68 μF, 100 μF, 150 μF, 220 μF, 330 μF, 470 μF, 680 μF, 1000 μF, 1500 μF, 2200 μF, 3300 μF, 4700 μF, 6800 μF, 10000 μF

Lists

A decade of the E12 values shown with their electronic color codes on resistors.

List of values for each E series:<ref group="nb" name="NB_E1"/>

E3 values

(40% tolerance)

1.0, 2.2, 4.7

E6 values

(20% tolerance)

1.0, 1.5, 2.2, 3.3, 4.7, 6.8

E12 values

(10% tolerance)

1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2

E24 values

(5% tolerance)

1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1

E48 values

(2% tolerance)

1.00, 1.05, 1.10, 1.15, 1.21, 1.27, 1.33, 1.40, 1.47, 1.54, 1.62, 1.69, 1.78, 1.87, 1.96, 2.05, 2.15, 2.26, 2.37, 2.49, 2.61, 2.74, 2.87, 3.01, 3.16, 3.32, 3.48, 3.65, 3.83, 4.02, 4.22, 4.42, 4.64, 4.87, 5.11, 5.36, 5.62, 5.90, 6.19, 6.49, 6.81, 7.15, 7.50, 7.87, 8.25, 8.66, 9.09, 9.53

E96 values

(1% tolerance)

1.00, 1.02, 1.05, 1.07, 1.10, 1.13, 1.15, 1.18, 1.21, 1.24, 1.27, 1.30, 1.33, 1.37, 1.40, 1.43, 1.47, 1.50, 1.54, 1.58, 1.62, 1.65, 1.69, 1.74, 1.78, 1.82, 1.87, 1.91, 1.96, 2.00, 2.05, 2.10, 2.15, 2.21, 2.26, 2.32, 2.37, 2.43, 2.49, 2.55, 2.61, 2.67, 2.74, 2.80, 2.87, 2.94, 3.01, 3.09, 3.16, 3.24, 3.32, 3.40, 3.48, 3.57, 3.65, 3.74, 3.83, 3.92, 4.02, 4.12, 4.22, 4.32, 4.42, 4.53, 4.64, 4.75, 4.87, 4.99, 5.11, 5.23, 5.36, 5.49, 5.62, 5.76, 5.90, 6.04, 6.19, 6.34, 6.49, 6.65, 6.81, 6.98, 7.15, 7.32, 7.50, 7.68, 7.87, 8.06, 8.25, 8.45, 8.66, 8.87, 9.09, 9.31, 9.53, 9.76

E192 values

(0.5% and lower tolerance)

1.00, 1.01, 1.02, 1.04, 1.05, 1.06, 1.07, 1.09, 1.10, 1.11, 1.13, 1.14, 1.15, 1.17, 1.18, 1.20, 1.21, 1.23, 1.24, 1.26, 1.27, 1.29, 1.30, 1.32, 1.33, 1.35, 1.37, 1.38, 1.40, 1.42, 1.43, 1.45, 1.47, 1.49, 1.50, 1.52, 1.54, 1.56, 1.58, 1.60, 1.62, 1.64, 1.65, 1.67, 1.69, 1.72, 1.74, 1.76, 1.78, 1.80, 1.82, 1.84, 1.87, 1.89, 1.91, 1.93, 1.96, 1.98, 2.00, 2.03, 2.05, 2.08, 2.10, 2.13, 2.15, 2.18, 2.21, 2.23, 2.26, 2.29, 2.32, 2.34, 2.37, 2.40, 2.43, 2.46, 2.49, 2.52, 2.55, 2.58, 2.61, 2.64, 2.67, 2.71, 2.74, 2.77, 2.80, 2.84, 2.87, 2.91, 2.94, 2.98, 3.01, 3.05, 3.09, 3.12, 3.16, 3.20, 3.24, 3.28, 3.32, 3.36, 3.40, 3.44, 3.48, 3.52, 3.57, 3.61, 3.65, 3.70, 3.74, 3.79, 3.83, 3.88, 3.92, 3.97, 4.02, 4.07, 4.12, 4.17, 4.22, 4.27, 4.32, 4.37, 4.42, 4.48, 4.53, 4.59, 4.64, 4.70, 4.75, 4.81, 4.87, 4.93, 4.99, 5.05, 5.11, 5.17, 5.23, 5.30, 5.36, 5.42, 5.49, 5.56, 5.62, 5.69, 5.76, 5.83, 5.90, 5.97, 6.04, 6.12, 6.19, 6.26, 6.34, 6.42, 6.49, 6.57, 6.65, 6.73, 6.81, 6.90, 6.98, 7.06, 7.15, 7.23, 7.32, 7.41, 7.50, 7.59, 7.68, 7.77, 7.87, 7.96, 8.06, 8.16, 8.25, 8.35, 8.45, 8.56, 8.66, 8.76, 8.87, 8.98, 9.09, 9.20, 9.31, 9.42, 9.53, 9.65, 9.76, 9.88

Table

E-series values, 1.0–2.13 E3 E6 E12 E24 E48 E96 E192 1.0 1.0 1.0 1.0 1.00 1.00 1.00 1.01 1.02 1.02 1.04 1.05 1.05 1.05 1.06 1.07 1.07 1.09 1.1 1.10 1.10 1.10 1.11 1.13 1.13 1.14 1.15 1.15 1.15 1.17 1.18 1.18 1.20 1.2 1.2 1.21 1.21 1.21 1.23 1.24 1.24 1.26 1.27 1.27 1.27 1.29 1.30 1.30 1.32 1.3 1.33 1.33 1.33 1.35 1.37 1.37 1.38 1.40 1.40 1.40 1.42 1.43 1.43 1.45 1.5 1.5 1.5 1.47 1.47 1.47 1.49 1.50 1.50 1.52 1.54 1.54 1.54 1.56 1.58 1.58 1.60 1.6 1.62 1.62 1.62 1.64 1.65 1.65 1.67 1.69 1.69 1.69 1.72 1.74 1.74 1.76 1.8 1.8 1.78 1.78 1.78 1.80 1.82 1.82 1.84 1.87 1.87 1.87 1.89 1.91 1.91 1.93 2.0 1.96 1.96 1.96 1.98 2.00 2.00 2.03 2.05 2.05 2.05 2.08 2.10 2.10 2.13

E-series values, 2.15–4.59 E3 E6 E12 E24 E48 E96 E192 2.2 2.2 2.2 2.2 2.15 2.15 2.15 2.18 2.21 2.21 2.23 2.26 2.26 2.26 2.29 2.32 2.32 2.34 2.4 2.37 2.37 2.37 2.40 2.43 2.43 2.46 2.49 2.49 2.49 2.52 2.55 2.55 2.58 2.7 2.7 2.61 2.61 2.61 2.64 2.67 2.67 2.71 2.74 2.74 2.74 2.77 2.80 2.80 2.84 3.0 2.87 2.87 2.87 2.91 2.94 2.94 2.98 3.01 3.01 3.01 3.05 3.09 3.09 3.12 3.3 3.3 3.3 3.16 3.16 3.16 3.20 3.24 3.24 3.28 3.32 3.32 3.32 3.36 3.40 3.40 3.44 3.6 3.48 3.48 3.48 3.52 3.57 3.57 3.61 3.65 3.65 3.65 3.70 3.74 3.74 3.79 3.9 3.9 3.83 3.83 3.83 3.88 3.92 3.92 3.97 4.02 4.02 4.02 4.07 4.12 4.12 4.17 4.3 4.22 4.22 4.22 4.27 4.32 4.32 4.37 4.42 4.42 4.42 4.48 4.53 4.53 4.59

E-series values, 4.64–9.88 E3 E6 E12 E24 E48 E96 E192 4.7 4.7 4.7 4.7 4.64 4.64 4.64 4.70 4.75 4.75 4.81 4.87 4.87 4.87 4.93 4.99 4.99 5.05 5.1 5.11 5.11 5.11 5.17 5.23 5.23 5.30 5.36 5.36 5.36 5.42 5.49 5.49 5.56 5.6 5.6 5.62 5.62 5.62 5.69 5.76 5.76 5.83 5.90 5.90 5.90 5.97 6.04 6.04 6.12 6.2 6.19 6.19 6.19 6.26 6.34 6.34 6.42 6.49 6.49 6.49 6.57 6.65 6.65 6.73 6.8 6.8 6.8 6.81 6.81 6.81 6.90 6.98 6.98 7.06 7.15 7.15 7.15 7.23 7.32 7.32 7.41 7.5 7.50 7.50 7.50 7.59 7.68 7.68 7.77 7.87 7.87 7.87 7.96 8.06 8.06 8.16 8.2 8.2 8.25 8.25 8.25 8.35 8.45 8.45 8.56 8.66 8.66 8.66 8.76 8.87 8.87 8.98 9.1 9.09 9.09 9.09 9.20 9.31 9.31 9.42 9.53 9.53 9.53 9.65 9.76 9.76 9.88

See also

• Electronic color code – color-code used to indicate the values of axial electronic components, such as resistors, capacitors, inductors, diodes (also see IEC 60062).
• Geometric progression
• Preferred number
• Renard series – used for current rating of electric fuses
• Three-character marking code for resistors – for (E48/)E96 values (see EIA-96 and IEC 60062:2016)
• Two-character marking code for capacitors – for (E3/E6/E12/)E24 values (see ANSI/EIA-198-D:1991, ANSI/EIA-198-1-E:1998, ANSI/EIA-198-1-F:2002 and IEC 60062:2016/AMD1:2019)
• Reference designator – Location identifier for a circuit component

External links

• Calculate the closest component value to any E-series with an Excel User Defined Function.
• Calculate standard resistor values in Excel – EDN magazine

Printable E series tables

• E6 to E96 Table – Servenger
• E3 to E192 Table – Vishay