How to Measure Your Foot at Home (and Actually Get the Right Shoe Size)

Most shoe returns I have processed over the years trace back to one thing: the buyer guessed their size from a shoe they already owned instead of measuring the foot itself. A Nike 10 and a Clarks 10 can differ by nearly a full centimeter inside. The foot does not change; the label does. So measure the foot once, keep the number in millimeters, and convert from there every time you shop. Here is exactly how I do it.

What you need

• Two sheets of A4 or letter paper
• A wall
• A pencil held straight up (not angled)
• A ruler or tape measure marked in millimeters
• Thin socks, or the socks you actually wear with the shoes you are buying

Do this in the evening. Feet swell 3–5 mm over a normal day, and a shoe that fits at 8 a.m. will pinch at 8 p.m.

Step 1: Trace the foot against a wall

Tape the paper to a hard floor with the short edge touching the wall. Stand with your heel pressed flat against the wall and your full weight on that foot. Weight matters: an unloaded foot is roughly 3–4 mm shorter and narrower than a loaded one, and you buy shoes to walk in, not to sit in.

Have someone mark the tip of your longest toe. For about 20–25% of people that is the second toe, not the big toe, so look before you mark. If you are alone, bend down and mark it yourself while keeping the heel on the wall.

Step 2: Measure length in millimeters

Measure from the wall edge of the paper to the mark. Write it down as a millimeter figure, e.g. 262 mm. Do not round yet.

Now repeat for the other foot. Almost everyone has a difference; 2–4 mm is typical and 6 mm or more is common enough that I see it weekly. You buy for the longer foot. Always.

Step 3: Measure width

Keep the foot loaded and trace around the widest part of the forefoot (the ball, where the toes join). Measure the widest point across the tracing. For a 260 mm foot, roughly 95–100 mm is a standard “D” width for men and “B” for women in US terms. Anything over about 104 mm on that length usually means you want a wide (2E) fitting, which brands such as New Balance offer as standard and Nike mostly does not.

Step 4: Add toe room

Foot length is not shoe length. A well-fitting shoe has roughly 10–15 mm of space in front of the longest toe (the width of a thumb pressed sideways). Running shoes sit at the higher end, dress shoes and sandals at the lower end.

So a 262 mm foot should be looking for an internal shoe length of about 272–277 mm. Brands that publish in millimeters or centimeters (most Japanese and Korean brands, and Asics globally) usually list the foot length the shoe is designed for, not the internal last length, so you can match your raw measurement directly. Brands that list only US/UK/EU numbers require a conversion, and that is where mistakes happen.

Step 5: Convert the millimeters to a size

This is the moment where the chart matters more than your instinct. Use the men’s shoe size converter or the women’s shoe size converter with the millimeter figure, not a US size from another shoe. For children, the kids’ shoe size converter handles the C/Y jump that confuses most parents.

For reference, here is how a few common measurements map on the standard adult scale. Individual brands drift from this, but it is the baseline every chart starts from:

Foot length	US Men	US Women	UK	EU	Japan/Korea (mm)
240 mm	6	7.5	5.5	38.5	240
250 mm	7	8.5	6.5	40	250
260 mm	8	9.5	7.5	41.5	260
270 mm	9	10.5	8.5	42.5	270
280 mm	10	11.5	9.5	44	280
290 mm	11	12.5	10.5	45	290

Notice the US men’s to women’s gap is 1.5 sizes, not 1. The UK number is one below the US men’s number. EU steps are 6.67 mm each, which is why EU 42 and 42.5 both exist and both show up as “US 9” on different sites.

Where people still go wrong

Rounding down. If you measure 266 mm, you are between a 270 (US 9) and a 260 (US 8). Go up. A slightly long shoe is fixable with an insole; a short shoe is a return.

Trusting a shoe’s printed size. The printed cm/mm on a tongue label is the foot size the shoe is intended for. On Nike it is fairly reliable; on many fashion brands it is copied from a generic chart and can be off by 5 mm.

Ignoring width. A foot that is wide for its length will feel “too small” in a shoe that is the right length. If the toes are cramped but the heel has extra room, the problem is width, not length. Try a wide fitting before sizing up.

Measuring in the morning. Covered above, but it is the single most common reason a pair “shrank” in the afternoon.

Keep the number, not the size

I keep foot length and width in my phone notes as “L 268 / R 264, width 101” and never think about US sizes until the checkout page. That one habit removes almost all sizing guesswork, whether the shoe is a Nike, an Adidas, or something from a brand you have never heard of. Combine the millimeter figure with the brand-specific pages, check the width, and you will be ordering the right size on the first attempt far more often than not.

FAQ

Should I measure with socks on?

Measure with the socks you will actually wear with that shoe. Thin dress socks add about 1 mm; thick winter socks or hiking socks can add 3–5 mm, which is close to half a size. The chart figures assume a thin sock.

My feet are different lengths. Which size do I buy?

Buy for the longer foot. If the difference is over 8 mm, a thin insole in the shoe on the shorter foot usually evens out the fit without going to a different size per shoe.

How often should I re-measure?

Once a year for adults is enough; feet get slightly longer and wider with age and after pregnancy. Children should be measured every 2–3 months under age 4 and every 4–6 months after that, since a child’s foot grows roughly 1 mm a month in the early years.