Information

Size Guide

Getting your On Cloudmonster size right means secure heel lockdown, confident midfoot hold, and enough toe room for your foot to spread naturally on longer road runs. Here is how to find that fit.

Measure both feetWear your running socksAllow a thumb-width of toe roomHalf-up if between sizes

End of day

Best time to measure

Thumb width

Toe clearance

Size up half

Between sizes

Road running

Intended use

How a well-fitted On Cloudmonster should feel

The engineered knit upper of the On Cloudmonster wraps the midfoot securely without creating pressure points. Your heel should sit firmly in the heel cup with minimal lift, and your toes should have room to spread during the propulsion phase without hitting the front of the shoe.

  • Snug midfoot hold without pinching
  • Heel stays seated through a full stride
  • Toe room roughly a thumb-width from longest toe to shoe end
  • Test the fit while wearing your actual running socks

How to measure your foot accurately

Feet are typically at their largest late in the day and after activity. Stand on a flat surface, measure both feet, and use the larger measurement as your size reference. If you are between US sizes, round up to the next half size.

  • Stand while measuring, not sitting
  • Measure foot length and forefoot width
  • Measure both feet and use the larger
  • Compare to our US size chart for the best match

On Cloudmonster sizing notes

The On Cloudmonster fits true to size for most runners. Runners with a wider forefoot or those who prefer extra toe room for marathon-distance training often find a half size up comfortable. The engineered knit adapts to foot shape over the first few runs.

Frequently asked questions

Does the On Cloudmonster run true to size?

Yes, for most runners the On Cloudmonster fits true to standard US sizing. If you have a wider forefoot or prefer extra room for long efforts, a half size up is a safe choice.

Should I size up for marathon training?

Many runners who log high mileage prefer a half size up to allow for foot swelling over longer distances. If your forefoot feels close in your current size, sizing up is a practical move.

What if one foot is larger than the other?

Use your larger foot as the size reference. You can adjust lacing on the smaller foot for a more secure hold without going down in size.

What socks should I wear when trying on or testing fit?

Use the same socks you plan to run in. Running-specific socks are typically thinner than casual socks and affect how the upper wraps the midfoot. Testing with the wrong sock can lead to an inaccurate size choice.