What Makes This Calculator More Advanced
Most calculators use only your total bodyweight, which treats someone at 20% body fat the same as someone at 40%. This one uses the Katch-McArdle formula when you provide body fat percentage, basing your metabolic rate on lean body mass instead of total weight, since muscle burns far more energy than fat does.
Protein is set off your lean mass rather than total bodyweight, and you get separate calorie and carb targets for training days versus rest days, so you're better fueled for lifting and still in a controlled deficit or surplus overall.
How This Calculator Works
With body fat %, we calculate lean body mass and use the Katch-McArdle formula for your baseline metabolic rate. Without it, we fall back to the Mifflin-St Jeor formula. Either way, we factor in your activity level to get maintenance calories (TDEE), then adjust for your goal and training experience, new lifters get a larger surplus allowance for muscle gain, advanced lifters get a tighter one since progress slows with experience.
Training day carbs are set higher to fuel your lifts and recovery; rest day carbs drop slightly with calories shifted toward fat, while protein stays constant every day.
Frequently Asked Questions
Do I need to know my body fat percentage?
No, but it makes the result meaningfully more accurate. A rough estimate from a mirror check or a body fat caliper is enough. Without it, we use a standard formula based on total weight.
Why does training experience change my numbers?
Newer lifters can build muscle and lose fat at the same time, so the plan allows a bit more flexibility. Advanced lifters see slower results per pound of effort, so the targets get tighter and more precise.
Should I retest my numbers?
Yes. Re-run the calculator every 4-6 weeks or whenever your weight shifts by more than 5-10 lbs.
Free Fat Loss & Muscle Building Guide
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