Which planet spins the fastest?

Jupiter, the fastest spinning planet in our Solar System, completes a rotation in just under 10 hours, giving it the shortest days.

This makes Jupiter's days the shortest of any planet in the Solar System. Since Jupiter is a gas planet, it does not rotate as a solid sphere.

Jupiter's equator rotates faster than its polar regions, with a speed of 28,273 miles per hour (about 43,000 kilometers per hour).
 

Jupiter's day ranges from 9 hours and 56 minutes at the poles to 9 hours and 50 minutes near the equator.