Why a tape measure beats a shoe size
Shoe sizes are labels, and labels differ between brands, between countries and between factories. Oopbuy shoes come from hundreds of different sellers, so a label is the least portable piece of information you can carry. A foot length in centimetres is portable everywhere.
Measuring takes five minutes. It saves the cost of a pair that does not fit, which is the single most common way buyers lose money on footwear.
The paper method
- Tape a sheet of A4 paper to the floor against a wall.
- Stand on it with your heel touching the wall.
- Mark the tip of your longest toe with a pencil, keeping the pencil vertical.
- Step off and measure from the paper's edge at the wall to the mark.
- Record the figure in centimetres, to one decimal place.
- Repeat on the other foot.
Use the larger of the two. Most people differ by a few millimetres, and shoes are not sold per foot.
The wall method
If you do not have paper, stand with your heel against a wall and place a book upright against your longest toe, parallel to the wall. Step away and measure the gap between the wall and the book. It is less accurate than the paper method because the book can shift, but it is close enough if you are careful.
Why evening matters
Feet swell during the day, especially after walking or in warm weather. A measurement taken first thing in the morning can be several millimetres short. Since shoes are worn during the day, the evening measurement is the one that matches reality.
Wear the socks you intend to wear with the shoes. A thick wool sock can add a few millimetres, and boots are usually worn with thicker socks than sneakers.
Measure your width too
Width is not usually listed on Chinese charts, but it is worth recording for your own reference. Measure across the widest part of the ball of your foot, from the inside edge to the outside edge, standing. Write it down beside your length.
| Measurement | How to take it | Why it helps |
|---|---|---|
| Foot length | Heel to longest toe, standing | The primary size decision |
| Foot width | Across the ball, standing | Deciding whether to size up |
| Instep height | Around the top of the foot | Choosing between laced and slip-on styles |
| Heel width | Around the back of the heel | Predicting heel slip |
Three of those four will never appear on a listing. They are useful for you, not for the seller — they tell you which styles to avoid.
Common measurement mistakes
- Measuring sitting down. The foot spreads and lengthens under weight; a seated measurement is short.
- Measuring to the big toe only. The second toe is longer for many people.
- Holding the pencil at an angle. It adds a few millimetres in the wrong direction.
- Using a worn-out shoe's insole. The insole has compressed and no longer matches the foot.
- Measuring once, years ago. Feet change with age, weight and activity.
From measurement to size
Take your number to the listing's chart. Find the foot-length column, and choose the size whose range includes your number. If you are at the top of a range, consider the next size up, particularly for boots and for any style with a stiff toe box.
Add roughly half a centimetre of room for normal walking comfort; more for running shoes, where the foot swells. Do not add room by choosing a larger size if the chart already includes it — check what the chart is measuring first.
Shoes you already own are a second opinion
Take a pair that fits well, pull out the insole and measure its length. Compare that with your foot length. The difference is the amount of room that pair gives you, and it is a useful target: if your best-fitting sneakers have 1 cm of insole beyond your foot, look for charts that leave a similar margin.
This is also a way to sanity-check a suspicious chart. If a listing claims that a 26 cm foot fits a shoe with a 24 cm insole, the chart is wrong.
Keep the numbers on your phone
Store foot length, width and the insole length of your best-fitting pair in a note. Add the sizes that worked from each seller you have used. After three or four pairs, you will have a personal size chart that is more reliable than any table on the internet — including ours. Our Oopbuy size chart guide explains how the conversion tables work, and the buying guide puts measurement into the full ordering process.