To measure your foot size, stand on a firm surface, mark the back of your heel and the end of your longest toe, and measure the distance between them. Repeat for the other foot. Use the longer measurement when checking the shoe brand’s size chart.
You will need paper, a pencil and a ruler. A second person makes the markings easier, especially if you find yourself leaning forward to reach your toes.
1. Set up on a hard, level floor
Keep the paper still and stand naturally with your weight supported on both feet. Follow the manufacturer’s instructions about socks: use the kind you expect to wear with the shoes when the guide calls for them. Try to measure at a time representative of when you will wear the shoes.
2. Mark heel-to-toe length
Keep the pencil upright and mark the furthest point of the heel and longest toe. The longest toe is not necessarily the big toe. Step away and measure the straight distance between the marks. Record the result in centimetres or millimetres, then repeat to check it. If the results differ noticeably, repeat the measurement instead of averaging an obvious mistake.
3. Measure the other foot
Do not assume both feet match. Keep both measurements in your notes and start with the longer one when consulting a chart. Nike also advises using the longer measurement in its footwear size guide.
4. Use the chart for the exact brand and product
A UK, US or EU size is a label, not a measurement you can safely carry between every brand. Check whether the chart asks for foot length, insole length or another measurement. Those are not interchangeable. Follow its instructions for a measurement between sizes rather than adding an arbitrary amount.
What about width?
Length is only part of the fit. If shoes often squeeze the sides of your feet, look for width options and the brand’s width guidance. A rough outline of the widest part of your foot can help you describe the issue, but it is not a universal width-size conversion.
Sizing up to gain width may leave too much length. A different width or shoe shape can be a better option.
Check the fit before wearing shoes outside
- Try both shoes with the socks you intend to use.
- Walk on a clean indoor surface if the retailer permits it.
- Check for rubbing, toe pressure and unwanted heel movement.
- Do not count on a painful fit becoming comfortable after use.
Keep the packaging until you are sure. Measurements narrow the search; they cannot guarantee comfort in every shoe shape. If you are comparing older running models, see our running shoe comparison.