62/38 in millimeters
On a card whose left and right borders add up to 6 mm, 62/38 centering means a 3.7 mm border on one side and 2.3 mm on the other, a difference of 1.4 mm. That's easy to see at arm's length.
Questions
Can a 62/38 card get a PSA 10?
Not with a 62/38 front. PSA's Gem Mint 10 needs about 55/45 or better on the front. On the back, 62/38 still allows a 10, since the back limit is 75/25.
Is 62/38 good centering?
62/38 is noticeably off-center. On the front it falls inside PSA's range for a 9, where a card can land on either a 9 or an 8.
See every ratio on the centering chart, or read the full centering requirements.