Extend your arms in front of you with your palms facing away.
Bring your hands together, forming a small hole by crossing the thumbs and fore fingers.
Choose a small object about 15-20 feet away from you. With both eyes open, focus on the object as you look through the small hole.
Close one eye and then the other. When you close one eye, the object will be stationary. When you close the other eye, the object should disappear from the hole or jump to one side.
If the object does not move when you cover one eye, then that eye is dominant. The eye that sees the object and does not move is the dominant eye.
Tips:
Hand-dominance does not always correlate with eye-dominance.
Most people automatically use their dominant eye when looking through a camera eyehole or a telescope.
What You Need:
Your arms and hands
A target about 15-20 feet away