Body Fat Goal Calorie Calculator

Body Fat vs Weight Loss The goal of most fitness plans is not to lose weight, it is to lose fat while keeping muscle. Weight loss includes water, muscle and fat, and the scale cannot tell you which you got. This calculator holds lean mass constant and asks what has to come off the fat side.

Key Formulas Fat Mass = Body Weight × (Body Fat % / 100) Lean Mass = Body Weight − Fat Mass Target Body Weight = Lean Mass / (1 − Target BF%) Target Fat Mass = Target Body Weight − Lean Mass Fat to Lose = Current Fat Mass − Target Fat Mass Weeks = Fat to Lose ÷ Weekly Fat Loss Rate Daily Deficit = (Weekly Fat Loss × 3,500) ÷ 7

Notice what the third line does. You do not simply take 7% off the weight, because losing fat also lowers the total the percentage is measured against. Lean mass stays put and becomes a larger share of a smaller body, so the target weight falls out of the lean mass, not out of the starting weight.

Example Weight: 185 lbs, Body Fat: 22%, Target BF: 15% Fat Mass: 185 × 0.22 = 40.7 lbs Lean Mass: 185 − 40.7 = 144.3 lbs Target weight: 144.3 / (1 − 0.15) = 169.8 lbs Target fat mass: 169.8 − 144.3 = 25.5 lbs Fat to lose: 40.7 − 25.5 = 15.2 lbs At 0.75 lbs/week: 15.2 / 0.75 = 20.3, so 21 weeks Daily deficit: (0.75 × 3,500) / 7 = 375 calories

Safe Fat Loss Rates

A useful sanity check that does not appear on most calculators: a sustainable rate scales with how much fat you are carrying. Someone at 35% body fat can run at the top of that table for months. Someone already at 12% trying to reach 8% cannot, and pushing the rate there costs muscle rather than saving time.

How Low Is Too Low Essential fat, the amount your body needs for hormone production and organ padding, is roughly 3 to 5% in men and 10 to 13% in women. Those are floors, not targets. Sustainable year-round ranges sit well above them: about 10 to 20% for men and 18 to 28% for women. Below roughly 8% for men or 15% for women you are in physique-contest territory, which athletes hold for days, not seasons, and which in women is closely associated with losing the menstrual cycle and with bone density loss.

Important Disclaimer Body fat measurement methods vary a lot in accuracy. DXA is the practical gold standard; calipers and bioimpedance carry 2 to 4 percentage points of error, which is often larger than the change you are trying to detect. The 3,500-calories-per-pound rule used here is a simplification that overstates long-run loss, because expenditure falls as you get smaller. Expect the real timeline to run somewhat longer than the number this page gives you.