Useful calculators
Estimate how your calorie intake and daily activity could influence your bodyweight over time.
Whether you’re aiming to lose weight, gain weight or maintain your current weight, this calculator helps you understand your estimated energy balance and how to review your progress.
Results are estimates, not guarantees.
2. Understand your results
Your result provides an approximate indication of how your bodyweight could change based on your estimated daily energy expenditure and planned calorie intake.
Your maintenance calories are themselves an estimate, calculated using factors such as your age, height, weight and activity level. Your actual energy expenditure can vary from day to day, and your calorie requirements can change as your bodyweight changes.
Your weight can also fluctuate because of hydration, food intake, digestion and changes in training. If you’re aiming to gain weight, the calculator cannot determine how much of that gain will come from muscle rather than body fat.
Use this result as a starting point, not a guaranteed prediction. Monitor your average bodyweight over several weeks and use your actual progress to help decide whether your calorie intake needs adjusting.
Compare your average bodyweight after a few weeks with your starting weight to see how your weight is actually changing.
Use an average of several weigh-ins where possible, rather than relying on a single day’s weight.
Actual average weekly weight change
Percentage change per week
Enter the number of weeks and your current average bodyweight to review your progress.
Context matters
As your weight changes, your body generally requires a different amount of energy. Changes in muscle mass and other tissues can also influence your resting energy requirements. This means your maintenance calories won’t necessarily stay the same throughout your goal.
Your daily energy expenditure depends partly on how active you are. Changes to your job, step count, training frequency or general movement can affect your maintenance calories, even if your planned workouts remain consistent.
Your actual calorie intake may differ from your planned intake because of portion sizes, food preparation, tracking accuracy and changes in eating habits. Food also requires energy to digest and process, which contributes to your total daily energy expenditure.
Hydration, sodium intake, carbohydrate intake, menstrual-cycle changes and digestive contents can affect scale weight. Increased training stress can also temporarily increase water retention, masking changes in body fat or other tissues.
Sleep and stress can influence appetite, food choices, training performance, recovery and daily activity. They can also affect short-term weight fluctuations, making progress harder to interpret from individual weigh-ins.
During prolonged weight loss, energy expenditure can decrease because you’re carrying less bodyweight and, in some cases, because your body reduces energy expenditure beyond what would be expected from weight change alone. During weight gain, energy requirements can also rise.
3. How to apply this
Your initial estimate is a starting point, not a fixed calorie requirement.
Once you’ve established your calorie target, monitor your average bodyweight over the following weeks.
If your weight is changing at roughly the rate you’re aiming for, you may not need to adjust anything.
If your progress is consistently faster or slower than expected, review your actual food intake, activity and training before deciding whether to change your calories.
Remember that short-term fluctuations are normal. A few days without a change on the scales doesn’t necessarily mean your progress has stopped.
As your bodyweight, activity and routine change, your calorie requirements may change too. Reassessing your estimate periodically can help keep your approach appropriate for your current circumstances.
4. Method and further reading
For a dynamic model that accounts for changes over time, see the NIH Body Weight Planner. This calculator does not implement the NIH dynamic weight-change model.
