Calculating client macros is the easy part. Choosing appropriate inputs, explaining the result and knowing when to adjust it are where coaching judgement matters.
Follow a repeatable workflow: collect relevant inputs, estimate initial calories, apply a suitable goal adjustment, set protein and fat, allocate remaining calories to carbohydrate, then review the trend against adherence and real-world progress.
A branded calculator can automate the arithmetic while keeping the coach responsible for interpretation and adjustment.