In terms of physical comfort, the fit is the most significant factor. You can’t just wear whatever barong is at your disposal as long as you can fit in it. Otherwise, you won’t be able to move much, or the excess fabric will keep getting in the way. Likewise, the fit also matters when it comes to how the barong will look on you. You will want it to wrap around your body enough that it doesn’t look stuffy or baggy. Here is how you will determine if the barong perfectly fits your figure.
For the length, the barong itself should reach the bottom of your butt. That is around the middle point between your shoulders and the base of your feet. If cut too short or too long, it would look awkward. For the sleeves, the length should cover your wrists and not go past that. Also, make sure that the seams on the sleeves are not located any lower than the top of your shoulder.
When it comes to the form, make sure that you can still maximize your range of motion when you try wearing your barong. It’s supposed to not feel suffocating for your chest, armpits, and upper back, yet not too spacious at the same time. For the collar, the available space should allow you to fit a finger in. Any tighter than that, and you won’t be able to breathe with ease.