SI — SYSTÈME INTERNATIONAL D'UNITÉS
The Metric System
The international standard for measurement used by scientists, engineers, and everyday people worldwide. A coherent system of units based on 7 defining constants.
7
Base Units
22
Derived Units
20+
SI Prefixes
195
Countries Using
What is the SI System?
Introduction
- • The International System of Units (SI) is the modern form of the metric system.
- • Adopted in 1960 at the 11th General Conference on Weights and Measures.
- • Built upon 7 base units from which all other units are derived.
- • The only system of measurement used by almost every country.
Key Advantages
- • Decimal-based: Easy conversions by powers of 10.
- • Coherent: No conversion factors between units of same quantity.
- • Universal: Used in science, industry, and commerce globally.
- • Precise: Defined by unchanging physical constants.