Are you following the Multi-Diet plan? I don't know much about that plan, but I can imagibe their protein calculator is using their own formula.

Their plan sound a bit misguided, simply because protein requirements should relate to current Lean Body Mass (LBM), not adeal weight.

Low protein requirements are a corner stone of the old food pyramid, and the low-fat diets plans, as they consider it none-essential, and they focus on more carbs.

It all depends on the plan you follow. I can go easily over 400 grams of protein, and my kidneys are fine.

Wa'il