Feetures sock sizing
Feetures prints 1 chart for the models here: adult. The Feetures size chart page shows each one as the maker prints it, with the models that use it.
adult: Use the published range and wear the left and right socks on the matching feet. The chart says nothing about wide feet, so sizing up is no promise of more room.
Look up your size. See the fit checklist for heel position, toe room and cuff clearance.
Wash and dry Feetures socks
Wash inside out in cold water and tumble dry low. Do not use bleach or fabric softener.
A different instruction on the exact sock takes precedence over general brand guidance. Use the care lookup and your own drying estimate in the rotation planner.
Guarantee and return checks
The lifetime guarantee includes replacement for holes, thinning, lost stretch or shrinking. Use the guarantee route for a pair that has developed one of those problems.
The guarantee page distinguishes a 30-day return for the original order from a replacement claim. Start an ordinary return promptly for a new pair you do not want to keep.