The formula that I use to target macros is based loosely on Dr. Jan Kwasniewski's Optimal Diet.
First figure you *ideal* weight in kilos. The weight where you could really strut a bikini. I call it the HSIS weight (Hot Stuff In Swimwear) For me 145lbs=65kg.
HSIS weight in kilos plus/minus 10% is the range for protein grams so for me that is about 58-72/day
HSIS weight divided by 2 is your target carbs, for me about 32
HSIS weight times 2 to 3 is the range for fat grams so the low end for me is 130 gams/day and that is tough to make.