Plug in your age, gender, current weight, height, formula (normal/lean mass), activity level, and weight goal (lose/maintain/gain). Click calculate and it will tell you how many grams of carbs, protein and fat you need to be in ketosis.

I suspect it's an average estimate, and will only give you a ball-park answer, but it's a good start.

https://healthyeater.com/keto-diet-macros

I have no affiliation with this page. I've been keto for decades, but a relative wanted info and I found this for her, and thought I'd share it with the group.