Slim Fit Polos run small. If you normally wear a Large, we suggest purchasing a 2XL. This however limits the largest size garment to those who wear XL sizes, as they would purchase a 3XL. The guide below shows the sizing by measurements. Review the chart to ensure you select the best size for your body type. Note the pictures below for visuals.

Model is 5'8 with a 47 inch chest. He is wearing a 2XL slim fit polo in the initial photo. Below this photo, you can see how the Large, Extra Large, 2X Large, and 3X Large fits his body type.