The easiest way to tell if a shoe is too big or too small is to take a look at how much room there is in the toe of the shoe. Generally speaking, there should be about one finger's width of space between your longest toe and the end of the shoe.
Gait Changes – If your shoes are too big, they can end up affecting your natural gait. This can lead you to walk in an unnatural and even dysfunctional manner as your work to keep your heel from slipping out of the shoe, which can lead to new foot pain or problems like Achilles Tendonitis.
If your shoes are too big in length, you might notice your foot sliding backwards and forwards, while shoes that are too wide will cause your feet to slide from side to side.
If the shoe's toe box is too small, your toes will rub against the top of the shoe and you will get calluses or sores. Check the space at the end of the shoe. Stand up and make sure there is 3/8" or 1/2" (about the width of your finger) between your longest toe (usually the second toe) and the end of the shoe.
The only time that you could wear a shoe in a bigger size is when purchasing a sneaker but you should only go up about half a size. The reason for this is that our feet tend to swell because fluid accumulates due to gravity with prolonged standing and weight baring activities.
A half-size represents a 1/8” difference. It may not seem significant but is enough to distinguish between comfort and discomfort. Because there is no standardisation for shoe sizing, a half size difference will also depend on the brand of shoe. With some makes, a half size will be more significant than others.
Shoes that are on the tighter side are likely to rub, and since this friction can cause blisters, it's best to have a bit of wiggle room. The ball of your foot should fit comfortably in the widest part of the shoe, and at the heel make sure that you have some room for slight heel slippage.
As a rule of thumb (or toe), you should have about 3/8″ to 1/2″ of room from the tip of your longest toe to the end of the shoe. Your big toe is not automatically your longest toe. Pick the shoes that match your foot shape.
The safety toe shell of the shoe should have plenty of empty space above the toes to keep the foot comfortable. The ideal range of room between the top of the foot and the top of the boot should again be in the 1-5mm range. This will keep the foot comfortable and prevents the toenails from bumping into the hard shell.
Insoles are your new best friend
Although often intended to help with posture problems and other discomfort, insoles are also useful to make shoes smaller by taking up extra space in footwear that's a tad on the big side. Full insoles are a fantastic solution if your shoes are too big across the length of your foot.
While most shoes will stretch and mold to fit your feet over time, many can be manually stretched. Leather shoes are easiest to stretch, but most fabrics and materials can also be stretched.
Without debate, by far the riskiest part of wearing shoes that are too loose is increasing your risk of various foot and ankle injuries. Whether it is jamming your toe or spraining an ankle, loose shoes aren't worth it.
One of the best ways to shrink shoes is by using the dryer. Most shoes can be dried in the dryer (learn how hot does a dryer get), however not all of them can, so be sure to check the shoe's care label before using this method.
When your foot bends to take a step in a new shoe, your heels should slip slightly. 1/8” movement is normal but can feel like much more. Loose slipping in the heels will not cause blisters when broken in gradually, but wearing shoes that are too small and tight will cause friction and then blister.
A wide toe-spread is a clear visual sign your feet are most likely in proper healthy, functional condition. Especially if the big toe isn't folded inwards (towards 2nd toe) but points forward in a straight line from the heel (hallux angle). A wide toe-spread, means a bigger thus better base of support.
Some people have a longer big toe, while others have longer second toes. Toe length ratio may be influenced by the amount of testosterone and estrogen present in the womb during early pregnancy.
If your laces are done up too tightly the footwear can squash your toes. If they are too loose this will cause your foot to move around and slide too far forward causing your toe nails to hit the front of your shoe. Find out more about lacing techniques in our How to Lace Walking Boots guide.
"Your foot is at its most swollen point early in the morning and you won't get as a good a fit as say, later in the afternoon," explained Dr. Positano. DON'T wear heels that are 3-inches or higher for long periods of time. If you're going to wear that shoe, try to sit down longer and not walk around constantly.
Typically shoes loosen up naturally as you wear them from place to place, but that entire process could take weeks of tiptoeing around with crunched toes and blooming blisters. But walking in shoes that pinch is something you can totally avoid.
The short answer is "no," new shoes should not hurt your feet. If your new shoes hurt, try your best to return them or exchange them for another size or a different style. Some shoe types are generally more narrow, and some have a restrictive toe box.
If you're between sizes, we recommend going up. As you can see, the difference of one whole size is only about a half-inch (less than 1 centimeter). The difference of a half size is—at most—a quarter of an inch. Opting for a larger shoe won't make a huge difference in fit, but it will be more comfortable overall.