How to Measure My Foot Size at Home, and Turn It Into a Shoe Size
How to measure my foot size at home: the standing paper-and-wall method, the math that turns millimetres into sizes, real average foot sizes, and width.
The short answer to how to measure my foot size: stand barefoot on a sheet of paper with your heel against a wall, mark the tip of your longest toe, measure the distance in millimetres, repeat on the other foot, and keep the larger number. Do it in the late afternoon. It takes about two minutes, and that one number is what every size chart is built on, including the one behind our shoe size conversion calculator.
The details matter more than they look. One US shoe size is a third of an inch, 8.47 mm, so a half size is only 4.2 mm. A pencil held at an angle, a foot measured sitting down, or a tape read from the wrong end can each move the result by that much. This guide covers the method, the arithmetic that turns a length into a size, four worked examples, what the feet of 6,068 measured US soldiers look like, and the dimension a size number leaves out: width.
What you need before you start
The kit is a sheet of paper longer than your foot (two sheets taped end to end for a large foot), a pencil, a hard floor next to a wall, and a ruler or tape measure marked in millimetres. Avoid carpet. The heel sinks, the paper creases, and the mark drifts, so use a hard floor or put a large book under the paper.
If there is no clear stretch of wall, any fixed square edge works: a heavy book stood on its end, a door frame, the side of a sturdy box. What the method needs is a flat reference for the heel to press against, so the measurement starts from a known zero.
Wear what you will wear in the shoe. For most shoes that means bare feet or thin socks. For hiking or winter boots, measure over the thick sock you will actually use, because it adds a couple of millimetres to the length and more to the girth.
How to measure my foot size, step by step
A second person makes this easier, but it works alone if you move slowly. The five steps:
- Tape the paper to the floor with one short edge flush against the wall.
- Stand on it with your full weight on the foot being measured and your heel touching the wall. Bend the knee slightly and let your weight move forward, the way you stand in a shoe.
- Hold the pencil straight up and down and mark the tip of your longest toe. On many feet that is the second toe, not the big toe.
- Step off and measure from the wall edge to the mark in a straight line, parallel to the long side of the paper.
- Repeat on the other foot and write down both numbers.
Three habits throw off an otherwise careful measurement. Tilting the pencil inward puts the mark short of the true toe tip, sometimes by several millimetres. Letting the tape wander off square reads a diagonal instead of a length and inflates the number. Lifting the heel while you mark the toe hands back something close to a seated measurement. If your two readings for the same foot differ by more than 2 or 3 mm, do it again.
Why standing, late in the day, and both feet
Body weight flattens the arch and spreads the foot forward, so a standing foot measures a few millimetres longer than the same foot measured sitting. Charts assume a weight-bearing foot, so a seated measurement quietly steers you toward a size that is too small. Feet also swell a little over a day on your feet. Measuring in the late afternoon captures the foot you will actually be walking on.
Almost nobody has two identical feet. A gap of a few millimetres between left and right is normal. A pair of shoes has one size, so fit the larger foot. The smaller foot gets some spare room, which a sock, an insole or a lacing change can take up; the reverse, a larger foot squeezed into the smaller foot's size, has no fix.
How many millimetres make a shoe size
The US and UK scales count in thirds of an inch, the old English barleycorn. The Continental European scale counts in Paris points of two-thirds of a centimetre, measured along the shoe rather than the foot. Japan and Korea skip the historical units and label the foot length itself in 5 mm steps, as China's current standard does (older Chinese labels double the centimetres and subtract 10). In millimetres:
A 4 mm measuring error is therefore already half a US size, and 7 mm is a whole EU size. That is why the pencil angle and the square tape matter: each can cost that much on its own.
A shoe size measurer turns the same idea into hardware. The Brannock Device, the sliding metal plate in shoe shops, was invented by Charles F. Brannock in 1925. It reads heel-to-toe length, heel-to-ball length and width in one placement. It is quicker and more consistent than paper, but it measures the same standing length the paper method does, so a careful home measurement should land within a few millimetres of it.
From foot length to shoe size: the formula
A foot length to shoe size men chart looks like a table of arbitrary numbers, but every row sits on one straight line. Wikipedia's shoe size article gives the US men's size as roughly three times the foot length in inches, minus 22:
Here S is the US men's size and L is the foot length in inches. The 3 is the three barleycorns in an inch, so every inch of foot adds three sizes, and the 22 fixes where the count starts. US women's sizes, on the most common retail convention, sit 1.5 higher for the same foot:
A metric measurement needs dividing by 2.54 before it goes into the formula. Rearranged, the same line tells you how to convert shoe size to inches, giving the foot length a size is built for:
A men's size 6 in inches is (6 + 22) ÷ 3 = 9.33 inches of foot, and a men's 10 is 10.67 inches. For a women's shoe size in inches, subtract 1.5 first: a women's 8 is a men's 6.5, which is 9.5 inches.
Worked example 1: a man between sizes
A man's larger foot measures 26.4 cm, which is 10.394 inches:
The calculator rounds to the nearest half size and shows a 9. But the foot sits just above a 9, which is built for 26.2 cm, rather than below it. For a close-fitting shoe such as a running shoe or a boot, try the 9.5 too. The 9.5 is built for a 26.7 cm foot, so it leaves him about 3 mm of spare room; the 9 is built for a foot 1.5 mm shorter than his.
Worked example 2: one measurement in every system
A woman's larger foot measures 24.4 cm. The formula gives a men's-scale 6.8, which rounds to 7, so her US women's size is 8.5. From the same length the calculator gives UK 6, EU 39.5, Japan 24.5 and China 39. By comparison, a 26 cm foot size is a men's 8.5 or a women's 10.
Worked example 3: a child with growing room
A four-year-old's foot measures 17.3 cm. The nearest row in the toddler chart is 10C at 17.1 cm, and the foot is already 2 mm past it. The next size, 11C, is built for 18.0 cm, leaving about 7 mm of room, close to one full size. Treat one size as the ceiling: in a shoe two or three sizes long, the foot slides forward with every step and the extra toe catches on stairs and kerbs.
Worked example 4: the insole trap
Someone measures the insole of a shoe that fits well, gets 28.6 cm, and types it in as foot length. The calculator returns a men's 12. The shoe was actually a 10. A shoe's last is longer than the foot it fits by an allowance that Wikipedia puts at 13 to 17 mm, close to two sizes. Take about 1.5 cm off an insole reading before converting, and 28.6 cm becomes 27.1 cm, a men's 10.
What the average foot size of a man and a woman really is
Pages about the average shoe size for men usually quote a single number with no source. A better answer comes from feet that were actually measured. The US Army's 2012 anthropometric survey, ANSUR II, measured 4,082 male and 1,986 female soldiers and published the raw data. Running those foot lengths through the same formula the calculator uses gives this:
| Percentile | Men's foot length | US men's size | Women's foot length | US women's size |
|---|---|---|---|---|
| 5th | 250 mm | 7.5 | 226 mm | 6 |
| 25th | 263 mm | 9 | 238 mm | 7.5 |
| 50th (median) | 271 mm | 10 | 246 mm | 8.5 |
| 75th | 280 mm | 11 | 254 mm | 9.5 |
| 95th | 293 mm | 12.5 | 268 mm | 11 |
The foot lengths are from the ANSUR II public data files; the sizes are computed with this site's conversion formulas. The mean male foot was 271.2 mm and the mean female foot 246.3 mm, so the average male shoe size by this route is a US men's 10 and the average shoe size for women a US women's 8.5. The middle half of each group spans only two sizes.
Women's foot size compared to men's is where the table surprises. The average woman's foot in the sample is 24.9 mm shorter, almost three full sizes, yet her label is only 1.5 lower, because women's numbers start 1.5 higher on the same foot. Soldiers are not a random sample of the population, so treat the table as a well-measured reference group rather than a census.
For a male foot size chart or a ladies foot size chart at every half size, use the adult charts on the calculator page, which list the foot length beside each US, UK, EU, Japan, China and Korea size. Print one and it doubles as a printable foot size chart: find your measured length in the foot length column and read across.
Measuring a child's foot
The paper-and-wall method works for children as it does for adults, with one change: have the child stand rather than holding a foot in the air, because a small child rarely keeps a foot still enough to mark, and standing gives the weight-bearing length the chart expects. Asking a small child to "stand like a statue" for five seconds helps.
What changes is how often. A common rule of thumb is to re-measure toddlers every two to three months and older children about twice a year. Between measurements, press a thumb across the toe of a worn shoe while the child stands; less than a thumb's width in front of the longest toe means it is time.
Children's sizes also use their own scale. US toddler and little-kid sizes run from 1C to 13.5C, then restart at 1Y for big kids, so a 1Y is larger than a 13C. The kids' chart on the calculator page lists every step from 1C to 6Y with its foot length, which avoids that trap entirely: measure, find the length, read the label.
Measuring width, and reading a shoe width chart
Length is what a size converts, but width is what most often makes a correctly sized shoe feel wrong. There are two ways to get it at home. Wrap a soft tape around the ball of the foot, just behind the toes, standing, snug but not tight, for the girth. Or trace the standing foot and measure straight across the widest point of the outline for the breadth.
Width scales with length more closely than people expect. In the ANSUR II data the mean foot breadth was 101.9 mm for men and 92.7 mm for women, and for both sexes the breadth averaged about 37.6% of foot length. In that sample women's feet were shorter, not narrower for their length. The spread around that average is wide, though. A 2019 study in Scientific Reports that analysed 1.2 million 3D foot scans from North America, Europe and Asia concluded that at least three widths per length class are needed to fit 90% of customers.
US brands mark width with letters, and the same letter means a different width for men and women. Read this as a men's shoe width chart and a women's one side by side:
| Width | Men's letter | Women's letter |
|---|---|---|
| Narrow | B | 2A (AA) |
| Medium (standard) | D | B |
| Wide | 2E (EE) | D |
| Extra wide | 4E (EEEE) | 2E (EE) |
These letters are a US retail convention, not a published standard, and the girth behind each letter varies between brands more than length does. If your foot is noticeably wide or narrow, a home measurement tells you to ask for a wide or narrow option up front; the fit itself is best settled by trying the shoe or ordering two widths from a shop with free returns.
Comparing measurement methods
The paper-and-wall method is not the only option, and it is worth knowing where it sits before assuming a gadget is better.
| Method | Typical accuracy | Cost | Time | Best for |
|---|---|---|---|---|
| Paper-and-wall (this guide) | Within a few millimetres, done carefully | Free | About 2 minutes | Most home measurements, adults and children |
| Printable paper ruler | Similar to paper-and-wall, if printed at 100% scale | Free (needs a printer) | About 2 minutes | Anyone without a ruler or tape measure |
| Phone camera app | Within a few millimetres, if calibrated | Free to a few dollars | 1 to 2 minutes | A quick re-check, or a foot that is hard to trace |
| Brannock Device | Highest, adds width and ball length | Free at a shoe shop | Under a minute | A first fit with an unfamiliar brand, or wide and narrow feet |
Done carefully, none of these disagree much. The real gap comes from technique, such as an angled pencil, a seated foot or a phone held at a tilt, far more often than from the method. Paper wins as the default because it needs nothing most homes lack and leaves no room for a calibration error.
Put the measurement to use
Take the larger foot's length to the shoe size conversion calculator and enter it in the foot length field. It returns US men's and women's, UK, EU, Japan/Mexico and China sizes at once, and its kids' mode reads a child's measurement against the C and Y scales. If your tape was in inches and the chart you are reading is in centimetres, the unit converter switches between them in one step.
Clothing that is sized from a body measurement follows the same logic of measuring first, then converting between national systems. The bra size calculator and our guide on how to measure bra size apply it to band and cup sizes, and the history of metric to imperial conversion explains why the US never adopted the metric system that Japanese and Korean sizes are built on.