%IACS
Percent IACS expresses conductivity relative to the International Annealed Copper Standard, a reference copper of exactly 58 MS/m at 20 °C. Pure annealed copper is about 100–103 %IACS; aluminium about 61 %IACS.
Symbol: %IACS
Quantity: electrical conductivity
SI relation: 1 %IACS = 580000 S/m (exact)
Derivation: 100 %IACS = 58 m/(Ω·mm²) = 58 MS/m at 20 °C, so 1 %IACS = 0.58 MS/m (exact)
Exact: yes, by definition
Reference conditions. 100 %IACS = 58 MS/m at 20 °C (International Annealed Copper Standard)
History
The International Annealed Copper Standard was adopted by the International Electrotechnical Commission in 1913 and chosen so that its conductivity is the whole number 58 m/(Ω·mm²).
Typical uses
- Copper and aluminium conductor grading
- Eddy-current conductivity testing of alloys and heat treatment
- Aerospace aluminium temper verification
Convert percent IACS to other units
| Conversion | 1 %IACS equals | Reverse |
|---|---|---|
| percent IACS to siemens per metre | 580000 S/m | siemens per metre to percent IACS |
| percent IACS to millisiemens per centimetre | 5800000 mS/cm | millisiemens per centimetre to percent IACS |
| percent IACS to microsiemens per centimetre | 5800000000 µS/cm | microsiemens per centimetre to percent IACS |
| percent IACS to megasiemens per metre | 0.58 MS/m | megasiemens per metre to percent IACS |
| percent IACS to decisiemens per metre | 5800000 dS/m | decisiemens per metre to percent IACS |
| percent IACS to siemens per centimetre | 5800 S/cm | siemens per centimetre to percent IACS |
| percent IACS to millisiemens per metre | 580000000 mS/m | millisiemens per metre to percent IACS |
Open the Electrical Conductivity Converter to convert any value between all units.
Sources
- Copper Wire Tables, NBS Handbook 100 (International Annealed Copper Standard), National Bureau of Standards (now NIST) , Section 1.2, International Annealed Copper Standard.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). %IACS. Retrieved October 25, 2026, from https://scientificconverters.com/units/percent-iacs/
IEEE
Scientific Converters, "%IACS," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/units/percent-iacs/