A person should check the fit of leather boots while standing. A leather boot should make the entire foot feel snug except for the heel. The ball of the foot should sit at the widest part of the sole of the boot. The instep, or vamp, of the boot should fit more snugly over the top of the arch than a normal shoe or sneaker.
The heel of the boot softens over time and conforms to the heel. One finger should fit between the heel and the back of the boot when the foot is pushed forward without lacing the boot. The toes should not be cramped in the boot while standing. There should be no pressure at the side of the foot at its widest points or on the big toe, and the toes should not touch the end of the boot when kicking a wall.
The heel should not move in the boot when rocking up and down. Test the ankle support and flexibility of the boots by standing on the sides of the feet. It is better to try on boots in the afternoon, as feet tend to be at their largest at this time of day.