Blue Collar Prepping has an interesting article about how to do this. It goes into more detail, and greater complexity, than the usual approach to determining MPBR, but it does so in a useful way and is well explained. Recommended reading for rifle shooters, whether novice or experienced.
If you haven't run into the concept before, here are a few articles explaining it:
- What is “Maximum Point Blank Range” Hunting?
- Maximum point-blank range
- Understanding MPBR For Better Shooting
- Learn Your Maximum Point-Blank Range