How to Pick Your Sneaker Size: a Guide from a Nha Trang Store

6 min read · Kiri Sneakers Outlet, Nha Trang

Running a sneaker store in Nha Trang taught us one simple thing: about half of all people wear the wrong size. Some were raised to buy shoes “with room to grow”, some trust the number on the box, and some have simply never measured their feet. Here's how to get it right — so your sneakers make you happy instead of giving you blisters.

Step 1. Measure your foot — it takes two minutes

Stand barefoot on a sheet of paper, put your weight on that leg, and trace your foot with a pencil. Measure from the heel to the tip of your longest toe. Do it for both feet — most people's feet differ by 2–4 mm, so go with the larger one.

One important detail: measure in the evening. Feet swell through the day and “grow” by about half a size — especially in a hot climate like Vietnam's. A pair that fits “snugly” in the morning will pinch by dinner.

Step 2. Add some room

Add 5–10 mm to your foot length. That's the space your toes need so they don't hit the toe box when you walk or go downhill. For running, aim closer to 10 mm; for everyday wear, 5–7 mm is enough.

Step 3. Convert centimetres to a size

This is where the confusion starts: US, UK, EU and centimetres all live their own lives. A rough guide for men's models:

Treat the table as a starting point only — every brand builds shoes on its own last, which brings us to the interesting part.

Why the same size fits differently in Nike and New Balance

• Nike traditionally runs small and a little narrow in the toe box. Many people are more comfortable going half a size up.
• Adidas is mostly true to size, though models with moulded soles can feel snugger.
• New Balance is the wide foot's best friend: a roomier last, and many models come in several widths.
• Puma is usually true to size, but the toe box can be on the narrow side.

The takeaway: “my size” is not one number but a range that depends on the brand and the specific model.

How to check the fit when trying on

1. Try shoes on with the socks you'll actually wear them with.
2. Stand up and walk around: the heel shouldn't slip, and the toes shouldn't touch the front.
3. There should be 5–10 mm in front of your longest toe — roughly the width of your thumb.
4. Wiggle your toes: they need room upward and sideways.
5. Torn between two sizes? Take the one that feels good after standing in it for 5 minutes — not the one you hope will “break in”.

Leather and suede stretch a little in width, but no material stretches in length. “They'll break in” is the most expensive myth in footwear.

The hot-climate factor

In Vietnam feet swell more than in temperate climates — heat and humidity do their work. If you're in Nha Trang for a while, allow a slightly bigger margin than at home. More on that in our post about sneakers for hot weather.

FAQ

Should I buy sneakers a size up “to be safe”?

No. More than 10 mm of extra room ruins the fit: the foot slides inside, blisters appear and the sole wears unevenly. The right margin is 5–10 mm.

Do sneakers really break in?

Leather and suede stretch slightly in width — never in length. If your toes touch the front during fitting, the pair is too small.

When is the best time to try shoes on?

In the afternoon or evening, when your feet are slightly swollen. That way you won't buy a pair that pinches by the end of the day.