The short answer
A mule fits when your whole heel rests on the footbed, your toes do not touch the front, and the vamp hugs your instep so the shoe follows your foot. Start with your usual size and the brand’s chart; if you are between sizes, the smaller size usually works better in a backless shoe, as long as your heel does not hang off the back.
The three checks
- Heel on the bed
Stand with your weight even. Your whole heel rests on the footbed, ideally in the heel cup if there is one, with no overhang at the back.
- Toe room
Your toes do not press against the front, or hang over it on an open toe. On a pointed toe, your toes should sit where the shoe is still wide, not in the point.
- Snug vamp
The top of the shoe hugs your instep firmly without pinching. Walk a few steps: the shoe should rise with your foot, not stay behind.
Size down or not?
Advice online splits. Some brands and reviewers suggest going down for open-back shoes; others report the same shoes run small. The safe approach:
- Use the brand chart. Dansko, for example, sizes in EU whole sizes and says its clogs may feel slightly snug as you step in.
- Between sizes, try the smaller. Extra length is the main cause of slipping in a mule.
- Do not size down past your heel. If your heel lands on the back edge, go back up.
- Read the reviews for the exact model. Look for "runs large" or "runs small" patterns. Bloomingdale’s reviewers, for instance, say the Tory Burch Pierced Mule runs large.
Fit by style
Fit by mule style
| Style | Fit note |
|---|---|
| Flat mules | Length is everything; a long flat mule slaps. |
| Heeled mules | Your foot slides forward on the slope; the vamp must be snug and toes still need room. |
| Loafer mules | Usually close to your loafer size; the high vamp helps. |
| Clogs | Firmer and roomier; a little heel movement is expected. |
| Wide feet | Buy width (W), never extra length. |
| Lined mules | Plush linings compress, so a snug start is fine. |
Fixes for mules that slip
- Heel grips stuck under the vamp take up a little volume. Search heel grips.
- Ball of foot pads stop your foot sliding forward in heels.
- Toe inserts fill an over-long pointed toe. Search toe inserts.
- A different shape: a higher vamp, a strap or a buckle style fixes what pads cannot.
When to try them on
Feet swell through the day, so try mules on in the afternoon, with the socks or tights you plan to wear, and walk on a hard floor indoors before you take the tags off. Keep the box until you are sure.
Questions people ask
Should mules be a half size smaller?
Not by default. Start with your usual size and the brand chart. If you are between sizes, try the smaller one first, because extra length is what makes mules slip. Your heel must still sit fully on the footbed.
Is it normal for your heel to lift in mules?
A little lift as you walk is normal; that is how a backless shoe moves. Dansko’s size guide even says the heel should move up and down freely in its clogs. A heel that slides sideways or off the footbed means the fit is wrong.
Why do my mules keep slipping off?
Usually the shoe is too long, the vamp is too low or loose for your foot, or the footbed is slippery. Try a half size down, a style with a higher vamp or a strap, or a grip pad under the ball of the foot.
Should your heel hang off a mule?
No. Your heel should rest on the footbed. Overhang strains the back edge, wears the shoe and is less stable.
Sources
Last reviewed October 12, 2026. Styles, sizes and availability change; check the listing before you buy.