I bought both sizes in orange and black. The medium fits my iphone 14 pro with a case, but I have to work it into the bag. This isn't an issue to me- just trying to describe the snug fit. The large has enough space to slip the iphone 14 in and out quickly. The large also fits the iphone 16 comfortably. I love both sizes for different reasons. The medium is great for long runs, when I wear pace tights and my phone gets sweaty sitting in the thigh pocket.
The large size is very ideal to keep my wallet, lip balm, hair ties, keys and other items in one place. I use the larger bag for my hiking packs, work backpack and medium to large purses where items can enter a black hole. My husband also has his own Janji pouch (size L) that he uses for his backpack when commuting by bike or hiking.