The only thing necessary for ketosis is lack of insulin, which can be achieved by low carb and moderate protein. The amount of fat you eat is pretty much irrelevant for ketosis, because for the body it does not really matter much if it uses the fat you eat or your body fat for fuel. With the lack of carbs and protein, it will happily produce ketones from whatever fat is available. There is also a lower limit of fat intake because the body can give off body fat only quite slowly, but the calculator should take care of that.
PS: Yesterday I've updated the calculator to make it a bit more intuitive: Keto Calculator. I am happy for any suggestion to improve it!