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Weight Loss Calculator

Estimate a daily calorie target from TDEE and a percentage-based weekly weight-loss pace. Add an intended target weight for an optional adult BMI reference check.

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Your Weight Loss Result

Daily calorie target —

Practical interpretation

Important: Estimate only—not medical advice.

How the Weight Loss Calculator works

Formula: TDEE = Mifflin–St Jeor BMR × activity factor; weekly loss = weight × selected percentage; daily deficit ≈ weekly kg × 7,700 ÷ 7; target = TDEE − deficit.

The selected rate scales with current body weight instead of applying a fixed 500-calorie deficit. If supplied, the intended target is compared with the adult BMI lower reference of 18.5 using height. Targets below 1,200 kcal for females or 1,500 kcal for males are rejected with guidance to select a slower pace.

Assumptions and limits: The 7,700 kcal/kg value is a static planning approximation, not a prediction of linear long-term weight loss. Metabolic adaptation, water, appetite, activity, and adherence change over time. Results are estimates for education and planning, not medical advice.

How to use your result

Use the result as a starting point, not a pass-or-fail score. Keep your inputs consistent, observe relevant trends over time, and adjust only when the trend—not one day—shows the estimate does not fit your needs.

Body measurements and equation-based targets always contain uncertainty. If your result conflicts with symptoms, a diagnosis, medication guidance, pregnancy needs, an eating-disorder recovery plan, or instructions from your care team, follow your qualified health professional.

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Frequently Asked Questions

How does the Weight Loss Calculator set a calorie target?

It estimates resting energy with the Mifflin–St Jeor equation, applies your activity factor to estimate TDEE, and subtracts the daily deficit associated with your selected weekly percentage. The result is a planning estimate, not a guaranteed intake or outcome.

Why is the weekly loss rate a percentage of body weight?

A percentage scales the starting pace to current body weight instead of assigning everyone the same fixed deficit. This calculator offers 0.25%, 0.5%, 0.75%, and 1.0% per week, but an appropriate pace depends on individual context.

What does the optional intended target weight do?

It does not change the calorie calculation. When entered, it lets the calculator compare that target with the lower adult BMI reference of 18.5 for your height and show a non-blocking caution if the target is below that reference.

Why can the calculator reject a selected loss rate?

The calculator rejects combinations that estimate less than 1,200 kcal per day for females or 1,500 kcal per day for males. These are calculator guardrails, not personalized prescriptions; choose a slower rate or seek qualified guidance.

Does 7,700 kcal always equal one kilogram of weight loss?

No. The 7,700 kcal per kilogram value is a static planning approximation. Real weight change is not linear because water, energy expenditure, appetite, activity, body composition, and adherence change over time.

How accurate is the estimated daily calorie target?

TDEE equations estimate population averages and can differ from measured needs. Track a multi-week body-weight trend, energy, performance, and adherence, then reassess after a meaningful change instead of reacting to daily scale fluctuations.

Can I use kilograms or pounds?

Yes. You can enter metric or imperial measurements. Imperial values are converted to canonical metric values for the formula, and weight-related results are displayed in your selected unit system.

Who should get individualized guidance before losing weight?

Minors, pregnant or breastfeeding people, anyone with an eating-disorder history, and people managing a medical condition or medication should consult a qualified clinician. This calculator is educational and is not medical advice.

Scientific References

  1. A new predictive equation for resting energy expenditure in healthy individuals American Journal of Clinical Nutrition
  2. What is the required energy deficit per unit weight loss? International Journal of Obesity
  3. Body Weight Planner National Institute of Diabetes and Digestive and Kidney Diseases
  4. Steps for Losing Weight Centers for Disease Control and Prevention
  5. Adult BMI Categories Centers for Disease Control and Prevention
  6. Healthy Weight and Heart Health National Heart, Lung, and Blood Institute

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