Loosen stiff ankles before you load them.
Move through the biggest circle you can and keep the rest of your leg still.
Ankle circles are joint prep, pure and simple, tracing the biggest circle your ankle can draw moves it through every direction it owns, warming the calves and all the small stabilising tissue around the joint before you load it. Working one foot at a time lets you compare sides and find the stiff one, which is usually the one that needed this most. They earn a place at the top of any session involving running, jumping, or squatting, which is to say most sessions.
Yes, they move the joint through its full range with control, increasing blood flow and easing stiffness before you ask the ankle to handle load or impact. They will not build strength, that is not their job, preparation is.
Around 8 to 10 slow circles each direction, each foot. Big and slow beats fast and small, the goal is the largest smooth circle your ankle can trace, not speed.
At the start of a warm-up, before calf raises, jumping, running, or deep squatting, and any time your ankles feel stiff, at a desk, after sitting, mid-flight. One ankle at a time also makes them a decent balance check if you do them standing.
