E24 series

E24 series

resistors on the PCB

Values such as 22 nF (0.022 μF) or 47 kΩ, which are often found in electronic components, may seem somewhat strange when you encounter them for the first time. Such values are referred to as the E6, E12, and E24 series. They are recommended values for resistors and capacitors, prepared by the International Electrotechnical Commissionfs (IEC) Technical Committee (TC) No.40, "Resistors and Capacitors", and are defined in IEC 60063 (JIS C 5063 in Japan).

Online calculator — Approximate the given value with ratio or product of E24 or E96 series values or mixed seried values.

Approximate with in

Orign and History

At the 1948 meeting of IEC TC No. 12, Radio-communication, in Stockholm, it was unanimously agreed that one of the most urgent matters for international standardization was a series of recommended values for resistors and capacitors up to 0.1 μF. It might have been desirable to standardize the ¹⁰√10 series system, but in several countries, the ¹²√10 series system had been adopted due to the standardization of 5%, 10%, and 20% tolerance for the aforementioned components. Changing this was unrealistic, so the ¹²√10 system was adopted .
In 1950 a proposal for recommended values for the E6, E12 and E24 series was adopted in Paris, and subsequently published as I.E.C. Publication 63.

The Secret of the E24 Series

Unfortunately, I do not know how the specific numbers were decided by the Technical Committee. However, it turns out that the E24 series subtly deviates from the values rounded to two digits after dividing one digit into 24 equal parts in a geometric progression. This deviation occurs around one third of a digit, between 2.7 and 4.7 (See Table 1).

Table 1 [ E24 / E12 / E6 Series and Geometric Series ]

E24 series
(5 % tolerance) E12 series
(10 % tolerance) E6 series
(20 % tolerance) ¹²√10 Geometric series

1.0 1.0 1.0 1.000

1.1 1.100~

1.2 1.2 1.211~

1.3 1.333~

1.5 1.5 1.5 1.467~

1.6 1.615~

1.8 1.8 1.778~

2.0 1.957~

2.2 2.2 2.2 2.154~

2.4 2.371~

2.7 2.7 2.610~

3.0 2.872~

3.3 3.3 3.3 3.162~

3.6 3.480~

3.9 3.9 3.831~

4.3 4.216~

4.7 4.7 4.7 4.641~

5.1 5.108~

5.6 5.6 5.623~

6.2 6.189~

6.8 6.8 6.8 6.812~

7.5 7.498~

8.2 8.2 8.254~

9.1 9.085~

Thanks to this, you may appreciate the exquisite balance in choosing these values when designing circuits, as you can make the ratio or product of multiple elements a nice value, or slightly larger or smaller. In actual electronic circuits, especially analog circuits, it is often more important to have a product or ratio of values rather than the absolute value of components, such as time constants or the gain of an amplifier. Particularly, thanks to the adoption of '3.0' instead of '2.9', it is truly appreciated that ratios such as

1 : 2 : 4 → 75 : 150 : 300
or
1 : 4 : 5 : 6 : 8 : 9 : 10 : 11 : 12 : 13 : 17 → 3 : 12 : 15 : 18 : 24 : 27 : 30 : 33 : 36 : 39 : 51
or even reciprocally
4 : 6 : 8 : 9 : 12 → 1 / 36 : 1 / 24 : 1 / 18 : 1 / 16 : 1 / 12

can be created. If you look at Table 2, you can see that most of the practical magnifications can be realized with the ratio of the E24 series.

Table 2 [Examples of practical magnifications obtained with ratios in the E24 series]

× magnifications E24 value / E24 value (error)

× 0.268~ ( 2 -√3) 15 / 56 (+0.034%), 22 / 82 (-0.13%)

× 0.293~ ( 1 - 1 / √2) 24 / 82 (+0.072%), 22 / 75 (-0.15%)

× 0.414~ (√2 - 1) 91 / 22 (+0.14%), 6.2 / 15 (+0.21%)

× 0.732~ (√3 - 1) 11 / 15 (-0.18%), 22 / 30 (-0.18%)

× 1.1 11 / 10, 22 / 20, 33 / 30

× 1.2 (6 / 5) 12 / 10, 18 / 15, 24 / 20, 36 / 30

× 1.25 (5 / 4) 15 / 12, 20 / 16, 30 / 24

× 1.33~ (4 / 3) 100 / 75, 16 / 12, 20 / 15, 24 / 18, 36 / 27, 68 / 51

× 1.4 (7 / 5) 18 / 13 (-1.1%)

× 1.41 (√2) 51 / 36 (-0.17%), 130 / 91 (-1.0%)

× 1.5 (3 / 2) 15 / 10, 18 / 12, 24 / 16, 27 / 18, 30 / 20, 33 / 22, 36 / 24

× 1.6 (8 / 5) 120 / 75, 16 / 10

× 1.66~ (5 / 3) 20 / 12, 30 / 18

× 1.73 (√3) 130 / 75 (-0.07%)

× 1.75 (7 / 4) 82 / 47 (-0.3%)

× 1.8 (9 / 5) 18 / 10, 27 / 15, 36 / 20

× 2 150 / 75, 20 / 10, 22 / 11, 24 / 12, 30 / 15, 36 / 18

× 2.16~ (√10 - 1) 39 / 18 (+0.2%), 11 / 51 (+0.25%)

× 2.2 (11 / 5) 22 / 10, 33 / 15

× 2.25 (9 / 4) 27 / 12, 36 / 16

× 2.33~ (7 / 3) 56 / 24, 91 / 39

× 2.5 (5 / 2) 30 / 12, 75 / 30

× 2.6 (13 / 5) 39 / 15

× 2.66~ (8 / 3) 200 / 75

× 2.75 (11 / 4) 33 / 12

× 2.8 (14 / 5) 56 / 20

× 3 3 / 1, 33 / 11, 36 / 12, 39 / 13

× 3.16~ (√10) 16 / 5.1 (+0.78%), 51 / 16 (+0.79%)

× 3.2 (16 / 5) 240 / 75

× 3.25 (13 / 4) 39 / 12

× 3.4 (17 / 5) 51 / 15, 68 / 20

× 3.5 (7 / 2) 56 / 16

× 3.75 (15 / 4) 75 / 20

× 4 12 / 3, 300 / 75

× 4.25 (17 / 4) 51 / 12, 68 / 16

× 4.5 (9 / 2) 68 / 15 (+0.7%)

× 5 75 / 15, 10 / 20, 11 / 22, 12 / 24, 15 / 3, 180 / 36

× 5.5 (11 / 2) 11 / 2

× 6 12 / 2, 18 / 3

× 6.5 (13 / 2) 13 / 2

× 7 91 / 13

× 7.5 (15 / 2) 120 / 16, 15 / 2, 180 / 24, 270 / 36, 510 / 68, 75 / 10

× 8 120 / 15, 16 / 2, 24 / 3

× 8.5 (16 / 2) 330 / 39 (+0.45%)

× 9 18 / 2, 27 / 3

The E24 series was likely designed with consideration for both a just intonation scale (akin to a pure tone scale) and a well-tempered scale (akin to a mean scale), in order to facilitate the realization of favorable ratios.

Appendix A — Tolerances code of resistors

Resistance tolerances are mainly determined by rounding the R3 series (Renard numbers) to the nearest digit, primarily using the 1-2-5 series.

Table 3 [Example of tolerance code]

code tolerance [%] series color code

(S) 0.0010

(U) 0.0020

(X) 0.0025

E(V) 0.0050

L(T) 0.01 (Grey)

P(H) 0.02 (Yellow)

W(A) 0.05 Orange

B 0.10 Purple

C 0.25 Blue

D 0.50 E192 Green

F 1 E96 Brown

G 2 E48 Red

J 5 E24 Gold

K 10 E12 Silver

M 20 E6 plane

Compliant with IEC60062:2016 (JIS C 5062, JIS C 60062:2019 in Japan).
The code in parentheses () are examples of extensions by resistor manufacturers (e.g. Vishay).

Appendix B — Rated voltage of capacitors and their codes

The capacitance of capacitors primarily uses the E series, such as E6 or E12. However, the rated voltage uses values based on the R10 standard numbers (Renard numbers). The rated voltage of the capacitor represents the exponent as a number in the first character and the mantissa as an uppercase English letter in the second character. The mantissa corresponds to the R10 standard numbers {1.0, 1.25, 1.6, 2.0, 2.5, 3.15, 4.0, 5.0, 6.3, 8.0} with {A, B, C, D, E, F, G, H, J, K}.

Table 4 [Examples of rated voltages and their codes]

Code Tolerance
[V]

0E 2.5

0G 4.0

0L 5.5

0J 6.3

1A 10

1B 12.5

1C 16

1D 20

1E 25

(1V) 35

1G 40

1H 50

1J 63

1K 80

2A 100

(2Q) 110

2B 125

2C 160

(2P) 180

2D 200

2E 250

2F 315

(2V) 350

2G 400

(2W) 450

2H 500

2J 630

3A 1000

3B 1250

3C 1600

3D 2000

Compliant with IEC 60384-1:2016 (JIS C 5101-1:2019 in Japan)
The code in parentheses () are examples of extensions by resistor manufacturers.
As an aside, in JIS C 5101-1:2010 (IEC 60384-1:2008) under
2.3.3 Recommended values of rated voltage
there was a note stating
Note 2: In particular, if necessary, the rated voltages of 35V, 350V, and 450V from the R20 standard number series may be used.
However, this statement was removed in JIS C 5101-1:2019 2.3.3. Therefore, going forward, the rated voltages of 35 V, 350 V, and 450 V may become deprecated for new designs or may be phased out from the manufacturer's lineup.

Appendix C — Codes for temperature characteristics of Class-1 ceramic capacitors

Table 5 [Temperature Coefficients TC of Class-1 ceramic capacitors]

Code TC
ppm / °C TC tolerance
ppm Color code

C0G 0 ±30 Black

P2G -150 ±30 Orange

R2G -220 ±30 Yellow

S2H -330 ±60 Green

T2H -470 ±60 Blue

U2J -750 ±120 Violet

SL +350 ∼ -1000 Gray

Excerpt from IEC 60384-8:2015 (JIS C 5101-8:2018 in Japan)

Ceramic capacitors for temperature compensation other than zero temperature coefficient (C0G, NP0 characteristics, etc.) are almost extinct as of 2023, leaving only a few with P2G and U2J characteristics.

Revision History

▼ unfold / fold

[July 31, 2024] Rev.1.50
[July 17, 2024] Rev.1.47
[July 13, 2024] Rev.1.46
[May  15, 2023] Rev.1.45
[May   2, 2023] Rev.1.44
[June 27, 2019] Rev.1.43
[Apr. 18, 2018] Rev.1.42
[Feb. 12, 2015] Rev.1.41
[July  5, 2014] Rev.1.4 
[Nov. 18, 2014] Rev.1.31
[Apr. 13, 2012] Rev.1.3 
[May   7, 2009] Rev.1.2
[Apr. 23, 2009] Rev.1.1
[Apr. 22, 2009] Rev.1.0

This article is a modified version of the E24 series article that appeared in the May 2008 issue of Transistor Technology.

REFERENCE

CSI IEC 60063, PREFERRED NUMBER SERIES FORRESISTORS AND CAPACITORS
Takayuki HOSODA, "Q1-2 Why are the resistor values 1, 2.2, 3.3, 4.7 ... so close together?", Transistor Technology, May 2008, p.p.104-105, CQ Publishing

External links

Preferred number - E24 numbers defined in the IEC 60063 (JIS C 5063)

E24 series (5 % tolerance)	E12 series (10 % tolerance)	E6 series (20 % tolerance)	¹²√10 Geometric series
1.0	1.0	1.0	1.000
1.1			1.100~
1.2	1.2		1.211~
1.3			1.333~
1.5	1.5	1.5	1.467~
1.6			1.615~
1.8	1.8		1.778~
2.0			1.957~
2.2	2.2	2.2	2.154~
2.4			2.371~
2.7	2.7		2.610~
3.0			2.872~
3.3	3.3	3.3	3.162~
3.6			3.480~
3.9	3.9		3.831~
4.3			4.216~
4.7	4.7	4.7	4.641~
5.1			5.108~
5.6	5.6		5.623~
6.2			6.189~
6.8	6.8	6.8	6.812~
7.5			7.498~
8.2	8.2		8.254~
9.1			9.085~

× magnifications	E24 value / E24 value (error)
× 0.268~ ( 2 -√3)	15 / 56 (+0.034%), 22 / 82 (-0.13%)
× 0.293~ ( 1 - 1 / √2)	24 / 82 (+0.072%), 22 / 75 (-0.15%)
× 0.414~ (√2 - 1)	91 / 22 (+0.14%), 6.2 / 15 (+0.21%)
× 0.732~ (√3 - 1)	11 / 15 (-0.18%), 22 / 30 (-0.18%)
× 1.1	11 / 10, 22 / 20, 33 / 30
× 1.2 (6 / 5)	12 / 10, 18 / 15, 24 / 20, 36 / 30
× 1.25 (5 / 4)	15 / 12, 20 / 16, 30 / 24
× 1.33~ (4 / 3)	100 / 75, 16 / 12, 20 / 15, 24 / 18, 36 / 27, 68 / 51
× 1.4 (7 / 5)	18 / 13 (-1.1%)
× 1.41 (√2)	51 / 36 (-0.17%), 130 / 91 (-1.0%)
× 1.5 (3 / 2)	15 / 10, 18 / 12, 24 / 16, 27 / 18, 30 / 20, 33 / 22, 36 / 24
× 1.6 (8 / 5)	120 / 75, 16 / 10
× 1.66~ (5 / 3)	20 / 12, 30 / 18
× 1.73 (√3)	130 / 75 (-0.07%)
× 1.75 (7 / 4)	82 / 47 (-0.3%)
× 1.8 (9 / 5)	18 / 10, 27 / 15, 36 / 20
× 2	150 / 75, 20 / 10, 22 / 11, 24 / 12, 30 / 15, 36 / 18
× 2.16~ (√10 - 1)	39 / 18 (+0.2%), 11 / 51 (+0.25%)
× 2.2 (11 / 5)	22 / 10, 33 / 15
× 2.25 (9 / 4)	27 / 12, 36 / 16
× 2.33~ (7 / 3)	56 / 24, 91 / 39
× 2.5 (5 / 2)	30 / 12, 75 / 30
× 2.6 (13 / 5)	39 / 15
× 2.66~ (8 / 3)	200 / 75
× 2.75 (11 / 4)	33 / 12
× 2.8 (14 / 5)	56 / 20
× 3	3 / 1, 33 / 11, 36 / 12, 39 / 13
× 3.16~ (√10)	16 / 5.1 (+0.78%), 51 / 16 (+0.79%)
× 3.2 (16 / 5)	240 / 75
× 3.25 (13 / 4)	39 / 12
× 3.4 (17 / 5)	51 / 15, 68 / 20
× 3.5 (7 / 2)	56 / 16
× 3.75 (15 / 4)	75 / 20
× 4	12 / 3, 300 / 75
× 4.25 (17 / 4)	51 / 12, 68 / 16
× 4.5 (9 / 2)	68 / 15 (+0.7%)
× 5	75 / 15, 10 / 20, 11 / 22, 12 / 24, 15 / 3, 180 / 36
× 5.5 (11 / 2)	11 / 2
× 6	12 / 2, 18 / 3
× 6.5 (13 / 2)	13 / 2
× 7	91 / 13
× 7.5 (15 / 2)	120 / 16, 15 / 2, 180 / 24, 270 / 36, 510 / 68, 75 / 10
× 8	120 / 15, 16 / 2, 24 / 3
× 8.5 (16 / 2)	330 / 39 (+0.45%)
× 9	18 / 2, 27 / 3

code	tolerance [%]	series	color code
(S)	0.0010
(U)	0.0020
(X)	0.0025
E(V)	0.0050
L(T)	0.01		(Grey)
P(H)	0.02		(Yellow)
W(A)	0.05		Orange
B	0.10		Purple
C	0.25		Blue
D	0.50	E192	Green
F	1	E96	Brown
G	2	E48	Red
J	5	E24	Gold
K	10	E12	Silver
M	20	E6	plane

Code	Tolerance [V]
0E	2.5
0G	4.0
0L	5.5
0J	6.3
1A	10
1B	12.5
1C	16
1D	20
1E	25
(1V)	35
1G	40
1H	50
1J	63
1K	80
2A	100
(2Q)	110
2B	125
2C	160
(2P)	180
2D	200
2E	250
2F	315
(2V)	350
2G	400
(2W)	450
2H	500
2J	630
3A	1000
3B	1250
3C	1600
3D	2000

Code	TC ppm / °C	TC tolerance ppm	Color code
C0G	0	±30	Black
P2G	-150	±30	Orange
R2G	-220	±30	Yellow
S2H	-330	±60	Green
T2H	-470	±60	Blue
U2J	-750	±120	Violet
SL	+350 ∼ -1000		Gray