Overview
Originally meant also as part marking code, this shorthand notation is widely used in electrical engineering to denote the values of resistors and capacitors in circuit diagrams and in the production of electronic circuits (for example in bills of material and inPart value code
For brevity, the notation omits to always specify the unit (8K2
indicates a resistor value of 8.2 kΩ. Additional zeros imply tighter tolerance, for example 15M0
.
When the value can be expressed without the need for a prefix, an "R" is used instead of the decimal separator. For example, 1R2
indicates 1.2 Ω, and 18R
indicates 18 Ω.
For ''resistances'', the standard dictates the use of the uppercase letters L
(for 10−3), R
(for 100 = 1), K
(for 103), M
(for 106), and G
(for 109) to be used instead of the decimal point.
The usage of the letter R
instead of the SI unit symbol Ω for ohms stems from the fact that the Greek letter Ω is absent from most older character encodings (though it is present in the now-ubiquitous R
was chosen because visually it loosely resembles the Ω glyph, and also because it works nicely as a mnemonic for ''r''esistance in many languages.
The letters G
and T
weren't part of the first issue of the standard, which pre-dates the introduction of the SI system (hence the name "RKM code"), but were added after the adoption of the corresponding SI prefixes.
The introduction of the letter L
in more recent issues of the standard (instead of an SI prefix m
for milli) is justified to maintain the rule of only using uppercase letters for resistances (the otherwise resulting M
was already in use for mega).
Similar, the standard prescribes the following lowercase letters for ''capacitances'' to be used instead of the decimal point: p
(for 10−12), n
(for 10−9), µ
(for 10−6), m
(for 10−3), but uppercase F
(for 100 = 1) for farad.
The letters p
and n
weren't part of the first issue of the standard, but were added after the adoption of the corresponding SI prefixes.
In cases where the Greek letter µ
is not available, the standard allows it to be replaced by u
(or U
, when only uppercase letters are available). This usage of u
instead of µ
is also in line with ISO 2955 (1974, 1983), DIN 66030 (Vornorm 1973; 1980, 2002), BS 6430 (1983) and μ
to be substituted by the letter u
(or U
) in circumstances in which only the Similar codes
Though non-standardized some manufacturers use the RKM code also to mark inductors with "R" marking the decimal point in microhenry (e.g. 4R7 for 4.7 μH). A similar not standardized notation using the unit symbol instead of a decimal separator is sometimes used to indicate voltages (3V3 for 3.3 V, or 1V8 for 1.8 V) in contexts where a decimal separator would be inappropriate (e.g. in signal names orTolerance code
Letter code for resistance and capacitance tolerances: Before the introduction of the RKM code, some of the letters for symmetrical tolerances (viz. G, J, K, M) were already used in US military contexts following theTemperature coefficient code
Letter codes for the temperature coefficient of resistance (TCR):Production date codes
Twenty-year cycle code
* First character: Year of production in twenty-year cycle ** A = 2030, 2010, 1990, 1970 ** B = 2031, 2011, 1991, 1971 ** C = 2032, 2012, 1992, 1972 ** D = 2033, 2013, 1993, 1973 ** E = 2034, 2014, 1994, 1974 ** F = 2035, 2015, 1995, 1975 ** H = 2036, 2016, 1996, 1976 ** J = 2037, 2017, 1997, 1977 ** K = 2038, 2018, 1998, 1978 ** L = 2039, 2019, 1999, 1979 ** M = 2020, 2000, 1980 ** N = 2021, 2001, 1981 ** P = 2022, 2002, 1982 ** R = 2023, 2003, 1983 ** S = 2024, 2004, 1984 ** T = 2025, 2005, 1985 ** U = 2026, 2006, 1986 ** V = 2027, 2007, 1987 ** W = 2028, 2008, 1988 ** X = 2029, 2009, 1989 * Second character: Month of production ** 1 to 9 = January to September ** O = October ** N = November ** D = December Example: J8 = August 2017 (or August 1997) Some manufacturers also used the production date code as a stand-alone code to indicate the production date of integrated circuits. Some manufacturers specify a three-character date code with a two-digit week number following the year letter. IEC 60062 also specifies a four-character year/week code.Ten-year cycle code
* First character: Year of production in ten-year cycle ** 0 = 2020 ** 1 = 2021 ** 2 = 2022, 2012 ** 3 = 2023, 2013 ** 4 = 2024, 2014 ** 5 = 2025, 2015 ** 6 = 2026, 2016 ** 7 = 2017 ** 8 = 2018 ** 9 = 2019 * Second character: Month of production ** 1 to 9 = January to September ** X = October ** Y = November ** Z = December Example: 78 = August 2017 IEC 60062 also specifies a four-character year/week code.Four-year cycle code
IEC 60062 also specifies a single-character four-year cycle year/month code.Marking codes for E series preferred values
Three-character resistor marking code
For resistances following the ( E48 or)Two-character capacitor marking code
For capacitances following the ( E3, E6, E12 or) E24 series of preferred values, the former ANSI/EIA-198-D:1991, ANSI/EIA-198-1-E:1998 and ANSI/EIA-198-1-F:2002 as well as the amendment IEC 60062:2016/AMD1:2019 to IEC 60062 define a '' special two-character marking code for capacitors'' for very small parts which leave no room to print any longer codes onto them. The code consists of an uppercase letter denoting the two significant digits of the value followed by a digit indicating the multiplier. The EIA standard also defines a number of lowercase letters to specify a number of values not found in E24.Corresponding standards
* IEC 62:1952 (aka IEC 60062:1952), first edition, 1952-01-01 * IEC 62:1968 (aka IEC 60062:1968), second edition, 1968-01-01 * IEC 62:1968/AMD1:1968 (aka IEC 60062:1968/AMD1:1968), amended second edition, 1968-12-31 * IEC 62:1974 (aka IEC 60062:1974) * IEC 62:1974/AMD1:1988 (aka IEC 60062:1974/AMD1:1988), amended third edition, 1988-04-30 * IEC 62:1974/AMD2:1989 (aka IEC 60062:1974/AMD2:1989), amended third edition, 1989-01-01 * IEC 62:1992 (aka IEC 60062:1992), fourth edition, 1992-03-15 * IEC 62:1992/AMD1:1995 (aka IEC 60062:1992/AMD1:1995), amended fourth edition, 1995-06-19 * IEC 60062:2004 (fifth edition, 2004-11-08) * IEC 60062:2016 (sixth edition, 2016-07-12) * IEC 60062:2016/COR1:2016 (corrected sixth edition, 2016-12-05) * IEC 60062:2016/AMD1:2019 (amendment 1, 2019-08-20) * IEC 60062:2016+AMD1:2019 CSV (consolidated version 6.1, 2019-08-20) * EN 60062:1993 * EN 60062:1994 (1994-10) * EN 60062:2005 * EN 60062:2016 * EN 60062:2016/AC:2016-12 (corrected edition) * EN 60062:2016/A1:2019 (amendment 1) * BS 1852:1975 (related to IEC 60062:1974) * BS EN 60062:1994 * BS EN 60062:2005 * BS EN 60062:2016 * DIN 40825:1973-04 (capacitor/resistor value code), DIN 41314:1975-12 (date code) * DIN IEC 62:1985-12 (aka DIN IEC 60062:1985-12) * DIN IEC 62:1989-10 (aka DIN IEC 60062:1989-10) * DIN IEC 62:1990-11 (aka DIN IEC 60062:1990-11) * DIN IEC 62:1993-03 (aka DIN IEC 60062:1993-03) * DIN EN 60062:1997-09 * DIN EN 60062:2001-11 * DIN EN 60062:2005-11 * ČSN EN 60062 * DS/EN 60062 * EVS-EN 60062 * (GOST) ГОСТ IEC 60062-2014 (related to IEC 60062-2004) * ILNAS-EN 60062 * I.S. EN 60062 * NEN EN IEC 60062 * NF EN 60062 * ÖVE/ÖNORM EN 60062 * PN-EN 60062 * prМКС EN 60062 * SN EN 60062 * TS 2932 EN 60062 * UNE-EN 60062 * BIS IS 4114-1967 * IS 8186-1976 (related to IEC 62:1974) * JIS C 5062 * TGL 31667See also
*Notes
References
{{List of IEC standards Standards