How calorie needs are estimated here
This calculator starts with basal metabolic rate, or BMR. BMR estimates how many calories your body uses at rest. It then multiplies BMR by an activity factor to estimate maintenance calories, also called total daily energy expenditure.
From that maintenance estimate, the calculator builds common planning targets for moderate fat loss, aggressive fat loss, and lean bulking.
Core formulas
Maintenance Calories = BMR ร activity multiplier
Moderate Cut = maintenance ร 0.85
Aggressive Cut = maintenance ร 0.75
Lean Bulk = maintenance ร 1.10
Mifflin-St Jeor is used as the main BMR estimate. Katch-McArdle is shown only when body fat percentage is available.
BMR vs maintenance calories
BMR is not the same as daily calorie needs. BMR estimates resting energy use only. Maintenance calories include movement, exercise, and general daily activity, which is why the maintenance number is higher.
This difference is important because most people should plan cuts, maintenance, and bulks from maintenance calories, not from BMR alone.
| Measure |
Meaning |
Used For |
| BMR | Resting baseline energy estimate | Starting point |
| Maintenance | BMR adjusted for activity | Weight maintenance planning |
| Cut target | Calories below maintenance | Fat loss planning |
| Lean bulk target | Calories above maintenance | Gradual gain planning |
Why Katch-McArdle is optional
Katch-McArdle uses lean body mass, so it requires body fat percentage. When body fat is entered, the calculator can compare a lean-mass-based BMR with the standard Mifflin-St Jeor result. If body fat is not entered, the main estimate remains Mifflin-St Jeor.
This is useful because the two methods may differ when body composition differs significantly from average assumptions.
Frequently Asked Questions
What is the difference between BMR and maintenance calories?+
BMR is the estimated energy your body uses at rest. Maintenance calories are your estimated daily calories after activity is added on top of BMR. Use the result as a practical starting point, not as a fixed prescription. Calorie needs, protein targets, macro splits, and maintenance estimates vary with body size, activity, metabolism, training history, appetite, tracking accuracy, and day-to-day movement. Adjust gradually using real progress and energy levels.
Why does the calculator show multiple targets?+
Because the best calorie target depends on the goal. Maintenance, fat loss, and lean bulking all require different energy levels. Use the result as a practical starting point, not as a fixed prescription. Calorie needs, protein targets, macro splits, and maintenance estimates vary with body size, activity, metabolism, training history, appetite, tracking accuracy, and day-to-day movement. Adjust gradually using real progress and energy levels.
What is a moderate cut?+
In this calculator, a moderate cut is about 15% below maintenance calories. It is a structured middle ground between maintenance and a more aggressive deficit. Use the result as a practical starting point, not as a fixed prescription. Calorie needs, protein targets, macro splits, and maintenance estimates vary with body size, activity, metabolism, training history, appetite, tracking accuracy, and day-to-day movement. Adjust gradually using real progress and energy levels.
Why is Katch-McArdle optional?+
Because it needs lean body mass, which requires body fat percentage. Without body fat input, the calculator cannot produce the Katch-McArdle estimate. Use the result as a practical starting point, not as a fixed prescription. Calorie needs, protein targets, macro splits, and maintenance estimates vary with body size, activity, metabolism, training history, appetite, tracking accuracy, and day-to-day movement. Adjust gradually using real progress and energy levels.
Are these calorie numbers exact?+
No. They are structured estimates. Real calorie needs vary with training load, body composition, movement, recovery, and measurement error. Use the result as a practical starting point, not as a fixed prescription. Calorie needs, protein targets, macro splits, and maintenance estimates vary with body size, activity, metabolism, training history, appetite, tracking accuracy, and day-to-day movement. Adjust gradually using real progress and energy levels.