This is a simple math calculator for air fuel ratio tuning. You enter your target AFR that you desire. Make a dyno run and record AFR data. Then Enter the data from the dyno run and data from your fuel map and then press calculate. the output from the app will be the new fuel map value you can try for getting closer to your desired AFR target. ex. if you target is 12.8 and your actual recorded while running is 12.0. then you will need to subtract fuel from your fuel map and the app will tell you what percentage you will need to remove from the map to run closer to your desired/target AFR.