HPTM measures a food's protein efficiency relative to your lean body mass (LBM). A score of 10 is a standardized benchmark: it means the food is dense enough to meet a 2g/LBM-kg target if total energy intake is scaled to a generic weight loss or maintenance level (approx. 20 kcal per kg of LBM).
Formula:HPTM = (Protein / (Calories * LBM)) * 10000
The metric does not account for your individual daily activity, but serves as a universal quality standard: foods with a score over 10 are on the "safe side," while foods under 10 require support from highly protein-dense choices to keep the day's total in balance.
The key insight of the HPTM metric and what makes it useful is that the protein requirement scales linearly while the calorie requirement does not. This means that it's much harder for bigger people to eat food of equivalent quality in terms of protein than it's for lighter people. Try changing the values in the calculator and observe how smaller people have higher HPTM scores. This essentially mean that less protein dense is better for them than the same food is relatively for bigger people. In other words, the food pyramid works as is for very light people, but for very large people it would be better inverted (as long as you cut the treats).