Difficult time understanding caloric requirement

hchavarria

Hello folks. I'm getting serious about my fitness goals and needed a place to track my calories and macronutrient requirements. Based on my needs i ended with LoseIt or MFP. I noticed that they both give different caloric need requirements and differ by 400 calories. I made sure i entered the same data in both apps but I have not found any data on how MFP calculates caloric needs. In LoseIt they do not account for excrcise and ask that you enter it yourself just like in MFP. Any insight on how MFP does this? I'm not saying its wrong I just need to understand where the difference comes from