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How Long to Hit Your Goal Body Fat Percentage

Going from 25% to 18% body fat when you weigh 180 lb means losing about 14 lb of fat, which takes roughly 28 weeks at a steady 0.5 lb of fat per week. Your target weight would be about 166 lb, because you keep your lean mass. The weekly calorie deficit works out to about 250 calories a day. We hold lean mass constant and only count fat lost.

Results

Visualization

BodyStd provides educational estimates only, using established formulas such as the 3,500-calorie-per-pound rule and the Mifflin-St Jeor equation. These tools do not diagnose any condition and are not medical advice. Weight-loss results vary widely by individual. Consult a physician or registered dietitian before starting any diet, exercise, or weight-loss program.

How It Works

Body fat is part of your total weight, so we first split weight into fat mass (weight x body fat %) and lean mass (the rest). We assume diet and training preserve lean mass, so the target weight is lean mass divided by (1 - goal body fat %). Fat to lose is the gap between current fat mass and the smaller fat mass at your goal. At a pace of R pounds of fat per week, weeks = fat to lose / R, and the daily deficit equals R x 3,500 / 7. The chart walks both body fat % and weight down together across the months.

What Should You Do?

Losing about 0.5-1 lb of fat per week is a realistic, muscle-sparing pace; faster rates tend to burn lean tissue and rebound. Keep protein high and lift weights so the scale drop is mostly fat. Re-measure body fat every few weeks rather than daily, because methods like calipers and scales have error. If the weeks-needed number feels long, that is normal: meaningful recomposition is a months-long project, not a quick fix.

Frequently Asked Questions

Why is my target weight higher than scale weight minus fat?

Because at a lower body fat % the same lean mass is a smaller share of total weight, so the goal weight includes the lean tissue you keep.

Is 0.5 lb of fat per week a good pace?

It is a safe, sustainable middle ground that protects muscle. Trained people may manage closer to 1 lb/week; beginners sometimes lose faster at first from water.

Do I really keep all my lean mass?

Not perfectly, but resistance training and adequate protein preserve most of it. The calculator assumes lean mass is held constant as a planning model.

How accurate are body fat scales?

Bioimpedance scales are convenient but can vary by hydration and time of day. Use trends, not single readings, and consider calipers or DEXA for a baseline.

Can women and men use the same math?

Yes. The formula is sex-neutral; only the healthy body fat ranges differ, which is why you set your own goal percentage.