Turn

General & non-SICurrent unit

One full revolution, 360 degrees or 2π radians.

The turn is the reference unit for angle on this site.

About the turn

A turn is the simplest angle to define: the whole way around, back to the starting direction. It also goes by cycle and revolution, and it equals 2π radians, 360 degrees, or 400 gradians. In the International System of Quantities, rotation is a plain count of revolutions, the angle divided by 2π radians, and it can be negative or exceed one.

Measuring in turns is older than it might seem. Percentage protractors marked in hundredths of a turn have existed since 1922, and in 1962 the astronomer Fred Hoyle proposed the terms centiturn, milliturn, and microturn. A 1974 German standard, DIN 1315, suggested the symbol pla, from the Latin for full angle. Some HP calculators, such as the HP Prime of 2013, accept tr as an angle unit. In CSS, 1turn equals 360deg, so a rule can rotate an element by 1.75turn. Binary angular measurement in computing also treats a full turn as the value 1, which lets integer overflow wrap an angle around for free.

Sources: Wikipedia: Turn (angle); MDN Web Docs: CSS <angle>; NIST Guide to the SI, Appendix B.8 (angle conversion factors)

Turn conversion chart

1 turn expressed in every other angle unit:

More General & non-SI units

• degree (angle)
• gradian (angle)
• arcminute (angle)
• arcsecond (angle)
• right angle (angle)
• octant (angle)
• sextant (angle)
• piece (counting & quantity)
• pair (counting & quantity)
• score (counting & quantity)
• hundred (counting & quantity)
• thousand (counting & quantity)
• million (counting & quantity)
• billion (short scale) (counting & quantity)
• trillion (short scale) (counting & quantity)
• billion (long scale) (counting & quantity)

All General & non-SI units

Browse all angle units.