Measure the penis. Use a ruler or measuring device to measure the length and girth of the erect penis. Make sure to measure the circumference at the base of the penis.
Use the measurements to find the right condom. Match the penis length and size to a condom size chart. Most brands provide a size chart that lists the different sizes of condoms that companies have.
Consider the condom material. Condoms can be made of different materials such as latex, polyisoprene or polyurethane, each of which has a different level of flexibility.
Try different brands and sizes. Just like other things, different condom brands produce condoms that fit differently, so try different brands and sizes to find the one that works best for you and your partner.