Gradian (gon)

Definition

One 400th of a full turn — used in surveying.

History

The gradian, or gon, divides the right angle into 100 parts, giving 400 to a full turn. It was introduced in France alongside the metric system to decimalise angle measure.

Where it is used

Gradians are used in surveying and some European engineering.

Typical uses include surveying, some European engineering.

Conversion pages

These pages convert gradian to or from another unit in angle.

No conversion pages use this unit yet.

Other Angle units

• Degree (°)
• Radian (rad)
• Revolution (rev)

Sources

• BIPM SI BIPM SI Brochure (2019); ISO 80000-3 (angle) · Dataset reviewed Nov 11, 2026