Here is a helpful guide for determining what size glove a baseball outfielder should use based on their age:
Age Range Recommended Glove Size
Under 8 years 10.5-11.5 inches
8-12 years 11.5-12 inches
12-16 years 12-12.75 inches
16+ years 12.75-13.5 inches
It's important to note that these are general recommendations and the best glove size may vary depending on the individual player's hand size and personal preference. It may also be helpful to try on different sizes and models to see which glove feels most comfortable and offers the best fit.
It's also worth noting that outfielders typically use larger gloves than infielders. A larger glove can provide more support and protection for the hand, as well as a larger pocket for easier catching.
Additional information for once you find the perfect glove →
Break it in properly! A new glove will be stiff and will need to be broken in. Have the player catch and throw a ball with the glove to soften it up. The player can also use a glove mallet to work the pocket, softening the leather and helping form the glove to their liking.