atto (a)

Document v1 · published by Koskamo · updated 2026-10-05

atto (symbol a) is the SI prefix for a factor of 10⁻¹⁸ (scaling factor 0.000000000000000001), per the BIPM SI Reference Point.

Name: atto
Symbol: a
Exponent: -18
Scaling factor: 0.000000000000000001
Value datatype: xsd:decimal
Defining resolution: https://si-digital-framework.org/bodies/CGPM#CGPM12-Res8

Source and provenance

Original source: si-digital-framework.org
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: BIPM SI Reference Point (si-digital-framework.org), the SI defining constants, base and derived units, and prefixes; CC BY 3.0 IGO

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Version history

Published by Koskamo2026-10-05
Version 1