Use a measuring tape to measure the length and circumference of each foot while standing. Measure from the heel to the longest toe for the length and at the ball of the foot for the circumference. Write down the sizes to compare with sock size charts.
Natural fibers like cotton have some stretch while synthetics have more stretch and recovery. Wool and blends will shrink some when washed and dried. Try on different fabrics to test how they stretch and fit on your actual feet. Account for differences in fibers when selecting the right sock size.
Casual and dress socks fit differently than athletic sock designs. Athletic socks incorporate more stretch to avoid constriction during activities. Hiking and work socks are usually thicker and may require sizing up. Looser casual socks should align closely to your actual foot size.
Socks shouldn't be painfully tight but also shouldn't have excessive bulging material in the toes. The ideal fit leaves some - but not too much - toe wiggle room for maximum comfort. Tight toe seams can lead to discomfort over time.
Wash socks delicately and allow to air dry when possible. Avoid high heat drying cycles that can damage the sock's elasticity over time. Fold and pair socks to help retain their original shape and fit. Replace socks with broken down elastic for maximum comfort.