Free health planning calculator
Weight Loss Calculator
Estimate a daily calorie target, timeline, and weight loss percentage from age, height, weight, activity level, and goal weight. Results are educational estimates and should not replace medical advice.
How the weight loss calculator works
This weight loss calculator estimates maintenance calories from basal metabolic rate and activity level, then compares that estimate with the calorie deficit required for your goal. The calculator uses body weight, height, age, sex, daily activity, target weight loss, and either a fixed number of days or a fixed daily calorie reduction.
The plan tab answers two common questions. If you know your deadline, it estimates the daily calorie target needed to reach the goal. If you know how many calories you can reduce each day, it estimates how many days the goal may take and the approximate target date.
Weight loss formula
The calculator estimates BMR with the Mifflin St Jeor equation: 10 x weight in kg + 6.25 x height in cm - 5 x age + 5 for men, or minus 161 for women. Maintenance calories are estimated by multiplying BMR by an activity factor. Weight loss energy is estimated as about 3,500 calories per pound, or about 7,700 calories per kilogram.
Safe use and realistic expectations
A calculator can help with planning, but real weight change varies with water weight, medication, hormones, sleep, training history, food tracking accuracy, and medical conditions. Many adults choose a slower deficit because it is easier to sustain, easier to recover from, and less likely to create very low calorie targets.
Do not use this calculator to diagnose, treat, or manage an eating disorder, pregnancy nutrition, adolescent growth, or a medical condition. For those cases, work with a qualified clinician or registered dietitian.
Frequently asked questions
What is a weight loss calculator?
A weight loss calculator estimates calorie needs, daily deficit, timeline, and weight loss percentage from personal measurements and a target.
How do I calculate weight loss percentage?
Subtract current weight from initial weight, divide by initial weight, then multiply by 100. For example, a change from 200 lb to 180 lb is 10%.
How many calories equal one pound of weight loss?
A common planning estimate is 3,500 calories per pound. It is useful for rough projections, but individual results can vary.
Is this calculator medical advice?
No. It is an educational planning tool. Ask a clinician before starting a major calorie deficit, especially if you have a medical condition or use medication that affects weight.