SI units and prefixes (BIPM SI Reference Point)

The 7 SI base units, 22 named SI derived units, and 24 SI prefixes from the BIPM SI Reference Point (the authoritative digital reference of the SI Digital Framework, CC BY 3.0 IGO). One document per unit or prefix: base units carry the current definition with its defining constant and superseded definitions, derived units the expression in base and other SI units, and prefixes the exponent and scaling factor.

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Documents

Showing 1–24 of 53 documents

Document	Version
ampere (A) The ampere (symbol A) is the SI base unit of electric current, per the BIPM SI Reference Point.	v1
atto (a) atto (symbol a) is the SI prefix for a factor of 10⁻¹⁸ (scaling factor 0.000000000000000001), per the BIPM SI Reference Point.	v1
becquerel (Bq) The becquerel (symbol Bq) is a named SI derived unit of activity referred to a radionuclide, per the BIPM SI Reference Point.	v1
candela (cd) The candela (symbol cd) is the SI base unit of luminous intensity, per the BIPM SI Reference Point.	v1
centi (c) centi (symbol c) is the SI prefix for a factor of 10⁻² (scaling factor 0.01), per the BIPM SI Reference Point.	v1
coulomb (C) The coulomb (symbol C) is a named SI derived unit of electric charge, per the BIPM SI Reference Point.	v1
deca (da) deca (symbol da) is the SI prefix for a factor of 10¹ (scaling factor 10), per the BIPM SI Reference Point.	v1
deci (d) deci (symbol d) is the SI prefix for a factor of 10⁻¹ (scaling factor 0.1), per the BIPM SI Reference Point.	v1
degree Celsius (°C) The degree Celsius (symbol °C) is a named SI derived unit of Celsius temperature, per the BIPM SI Reference Point.	v1
exa (E) exa (symbol E) is the SI prefix for a factor of 10¹⁸ (scaling factor 1000000000000000000), per the BIPM SI Reference Point.	v1
farad (F) The farad (symbol F) is a named SI derived unit of capacitance, per the BIPM SI Reference Point.	v1
femto (f) femto (symbol f) is the SI prefix for a factor of 10⁻¹⁵ (scaling factor 0.000000000000001), per the BIPM SI Reference Point.	v1
giga (G) giga (symbol G) is the SI prefix for a factor of 10⁹ (scaling factor 1000000000), per the BIPM SI Reference Point.	v1
gray (Gy) The gray (symbol Gy) is a named SI derived unit of absorbed dose and kerma, per the BIPM SI Reference Point.	v1
hecto (h) hecto (symbol h) is the SI prefix for a factor of 10² (scaling factor 100), per the BIPM SI Reference Point.	v1
henry (H) The henry (symbol H) is a named SI derived unit of inductance, per the BIPM SI Reference Point.	v1
hertz (Hz) The hertz (symbol Hz) is a named SI derived unit of frequency, per the BIPM SI Reference Point.	v1
joule (J) The joule (symbol J) is a named SI derived unit of energy, per the BIPM SI Reference Point.	v1
katal (kat) The katal (symbol kat) is a named SI derived unit of catalytic activity, per the BIPM SI Reference Point.	v1
kelvin (K) The kelvin (symbol K) is the SI base unit of thermodynamic temperature, per the BIPM SI Reference Point.	v1
kilo (k) kilo (symbol k) is the SI prefix for a factor of 10³ (scaling factor 1000), per the BIPM SI Reference Point.	v1
kilogram (kg) The kilogram (symbol kg) is the SI base unit of mass, per the BIPM SI Reference Point.	v1
lumen (lm) The lumen (symbol lm) is a named SI derived unit of luminous flux, per the BIPM SI Reference Point.	v1
lux (lx) The lux (symbol lx) is a named SI derived unit of illuminance, per the BIPM SI Reference Point.	v1

Source, review, and usage

Published on Koskamo by: Koskamo
Version: 54
Documents: 53 documents
Reviewed: 2026-10-05
Last approved change: 2026-10-05
Agent lookups: 0 in the last 90 days
Reuse: BIPM SI Reference Point (si-digital-framework.org), the SI defining constants, base and derived units, and prefixes; CC BY 3.0 IGO
Review status: Published by Koskamo; proposed revisions require Koskamo approval

Original sources are linked on each document. Owner approval records a publishing decision; it does not imply independent fact checking.

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Change history

Every change that reached this dataset. Proposals from contributors land only after Koskamo approves them.

Published by Koskamo2026-10-05
quecto (q) · v1
Published by Koskamo2026-10-05
ronto (r) · v1
Published by Koskamo2026-10-05
yocto (y) · v1
Published by Koskamo2026-10-05
zepto (z) · v1
Published by Koskamo2026-10-05
atto (a) · v1
Published by Koskamo2026-10-05
femto (f) · v1
Published by Koskamo2026-10-05
pico (p) · v1
Published by Koskamo2026-10-05
nano (n) · v1
Published by Koskamo2026-10-05
micro (μ) · v1
Published by Koskamo2026-10-05
milli (m) · v1