Side gapping happens when your shoe fits your heel and toes but leaves visible space along the midfoot or at the opening, making the shoe look sloppy and feel insecure. The core problem is almost always a mismatch between your foot’s volume and the shoe’s internal shape. The good news: most cases are fixable with the right combination of inserts, lacing adjustments, or smarter shoe choices going forward.
Why Shoes Gap on the Sides
Your foot has a three-dimensional shape, but most shoes are built on a standardized mold called a last. If your midfoot is narrower than average, or your instep (the top of your foot between ankle and toes) sits lower than the shoe expects, the upper material has nothing to press against and bows outward. People with higher arches tend to have a narrower midfoot, which compounds the problem. Those with flatter feet sometimes see gapping too, because their foot rolls inward and shifts away from the shoe’s side walls.
Width is the most overlooked factor. The standard shoe width scale runs from AAA (narrowest) through D and up to EEE (widest), with each step representing roughly an eighth of an inch. For women, the standard width is B, which fits a foot measuring about 3.9 to 4.0 inches across the ball. If your foot measures closer to 3.7 inches, you’re an A width, and a standard shoe will have noticeable slack on each side. That quarter-inch of total extra room is enough to create a visible gap.
Quick Fixes With Inserts and Pads
Tongue Pads
Tongue pads are small cushioned pads that stick to the underside of a shoe’s tongue. They take up volume at the instep and push your foot back and down into the heel cup. This repositions the foot so it sits more snugly against the sides of the shoe, closing the gap from the inside. They work especially well for loafers, oxfords, and any shoe where the opening sits over the top of the foot. You can find them in foam or leather, and they peel off without damaging the shoe if you want to try a different thickness.
Heel Grips
If the gapping is worst near the back of the shoe, heel grip liners can help. These are padded strips that adhere to the inside back of the shoe, reducing the internal volume around the heel. When your heel is locked in place, your midfoot can’t slide forward into the wider part of the shoe, which is a common cause of side gaps appearing after a few minutes of walking.
Moleskin for Targeted Spots
For smaller, localized gaps, adhesive moleskin works well. Hold a piece against the inside of the shoe where the gap forms, trace the area with a pencil, and cut to size. Stick it directly to the shoe’s interior lining. Moleskin adds a thin but effective layer of volume right where you need it, and it stays put through a full day of wear. You can layer two pieces for a thicker fill. Common placement spots are the inner side wall near the arch and just behind the ball of the foot.
Lacing Techniques That Close the Gap
If your shoes have laces, you already have the best tool for eliminating side gaps. Most people lace straight up and pull tight at the top, but this does almost nothing for midfoot gapping. Instead, focus tension on the middle eyelets, the ones that sit directly over the area where the gap forms. Pull these noticeably tighter than the bottom and top eyelets.
Many shoes also have an extra eyelet near the ankle that most people skip. Threading your laces through this top eyelet and creating a “heel lock” loop pulls the shoe snug against your ankle and prevents your foot from sliding forward. Nike recommends using these extra eyelets specifically to cinch shoes closer to the ankle for a narrower fit. This single adjustment can eliminate gapping in running shoes and sneakers almost entirely.
Shrinking Leather Shoes Safely
Leather shoes that have stretched over time can sometimes be tightened back up with moisture and controlled drying. The safest approach is to dampen the shoe’s exterior with a wet cloth, then let it air dry on a sunny windowsill. As the leather dries, it contracts slightly. For faster results, you can use a hair dryer on low heat held about six inches away from the surface, moving it constantly to avoid concentrating heat in one spot.
The critical step most people skip is conditioning afterward. Wetting and drying leather strips its natural oils, making it stiff and prone to cracking. Apply a leather conditioner once the shoes are completely dry to restore flexibility. You can repeat this process, but each cycle stresses the material, so two or three rounds is a reasonable limit. This method works best for minor gapping. If the leather has stretched significantly, a cobbler may tell you the material will simply keep stretching, especially with softer, thinner leathers.
Shoe Styles That Prevent Gapping
Some shoe designs are structurally prone to gapping, while others resist it. Pumps, ballet flats, and slip-ons are the worst offenders because they rely entirely on the shoe’s shape to hold your foot. There’s no adjustability, so any mismatch between your foot and the last creates a gap with no way to tighten it.
Shoes with laces, buckles, or straps give you control over fit. Mary Janes solve the problem with a strap across the instep that holds the foot down into the shoe. Lace-up boots and oxfords let you customize tension across the entire top of the foot. If you have a narrow midfoot, look for styles with a shallower toe box, a tapered heel, a higher built-in arch, and an outsole that narrows at the arch. These design features follow the contour of a narrower foot rather than fighting against it.
When shopping, also look for brands that sell in multiple widths. Buying a narrow width (A or AA for women, B for men) in your correct length will always fit better than buying a smaller size in standard width, which just shortens the shoe without addressing the real problem.
When Professional Help Makes Sense
A cobbler can add internal padding to specific areas, install elastic panels near the shoe’s opening, or take in the sides of certain leather shoes. That said, not every shoe is salvageable. Thin, soft leather that has already stretched may continue to stretch regardless of what a cobbler does. More structured leather and shoes with a firm counter (the stiff piece at the back of the heel) respond better to alterations.
If you’re dealing with gapping across multiple pairs of shoes, the issue is almost certainly your foot shape rather than any individual shoe. Getting your foot measured on a Brannock device at a shoe store takes about 30 seconds and gives you both your length and width. Knowing your actual width measurement saves you from buying standard-width shoes and trying to fix them after the fact. Many people have worn the wrong width for years simply because they’ve never been measured.