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Weight Loss Timeline Calculator

Sustainable weight loss starts with realistic expectations. This calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, then applies a daily calorie deficit matched to your chosen loss rate. Enter a goal weight to generate a week-by-week projection showing exactly where you could be at each step of your journey.

Quick Answer

Losing 1 lb per week requires a 500-calorie daily deficit. Enter your stats and goal weight to see a personalized week-by-week projection.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

Enter your details above to calculate your weight loss timeline.

How the Formula Works

  1. Calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation.

    Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

  2. Multiply BMR by your activity multiplier to get your Total Daily Energy Expenditure (TDEE).

    TDEE = BMR × Activity Multiplier (1.2 – 1.9)

  3. Derive your daily calorie deficit from the 3,500-calorie-per-pound rule.

    Deficit (cal/day) = Loss Rate (lbs/week) × 3,500 ÷ 7

  4. Subtract the deficit from your TDEE to get your daily calorie target.

    Daily Calories = TDEE − Deficit

  5. If a goal weight is provided, project weekly weight milestones from current weight to goal weight.

    Projected Weight (week n) = Starting Weight − (Loss Rate × n)

Methodology & Sources

Reviewed and updated April 5, 2026 · Prepared by GetHealthyCalculators Editorial Team

References

  • Dietary Reference Intakes for Energy · National Academies of Sciences, Engineering, and Medicine
  • Very Low-Calorie Diets · National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
  • Calorie restriction and weight loss in obese individuals · American Journal of Clinical Nutrition (AJCN)

Limitations

  • This calculator uses a linear weight loss model — real-world weight loss is non-linear due to metabolic adaptation, water weight fluctuations, and changes in body composition.
  • TDEE estimates carry a margin of error of roughly ±10%, meaning your actual calorie needs may differ from the projection.
  • The 3,500-calorie-per-pound rule is a simplification; it does not account for shifts in lean mass, glycogen stores, or hormonal adaptation.
  • As body weight decreases, TDEE also decreases — projections become less accurate over longer timelines without recalculation.
  • Water weight can cause significant short-term swings that do not reflect actual fat loss.
  • Consult a registered dietitian or physician before following any plan that brings your intake below 1,200 calories (women) or 1,500 calories (men) per day.

Frequently Asked Questions

How is the weight loss timeline calculated?
The calculator first estimates your TDEE using the Mifflin-St Jeor BMR equation and an activity multiplier. It then derives a daily calorie deficit from your chosen loss rate using the 3,500-calorie-per-pound rule (e.g., 1 lb/week = 500 cal/day deficit). If you enter a goal weight, it divides the total weight to lose by your weekly loss rate to estimate total weeks, then projects week-by-week milestones.
What is the safest rate of weight loss?
Most health guidelines recommend 0.5–1 lb (0.2–0.45 kg) per week as a safe, sustainable rate. Faster loss is possible but increases the risk of muscle loss, nutrient deficiencies, and metabolic slowdown. Rates above 2 lbs per week are generally not recommended without medical supervision.
Why does the calculator warn me about low calories?
Eating below 1,200 calories per day (women) or 1,500 calories per day (men) makes it very difficult to meet essential nutrient needs and can trigger metabolic adaptation — where your body reduces energy expenditure to match the lower intake. The warning is a prompt to consult a healthcare provider before following such a plan.
Why does the projection stop at 104 weeks?
The calculator caps projections at two years (104 weeks) because linear weight loss models become increasingly inaccurate over longer periods. Metabolic adaptation, changes in activity, and shifts in body composition all affect real-world results. Recalculating your TDEE every 10–15 lbs of weight loss will keep your projections accurate.
How often should I recalculate my calorie target?
As you lose weight, your TDEE decreases because a lighter body requires fewer calories to function. Re-entering your current weight into the calculator every 10–15 lbs (4–7 kg) of weight loss will ensure your daily calorie target remains accurate.
Can I use this calculator to plan weight loss after pregnancy?
This calculator is intended for general adult use and does not account for the specific caloric needs of postpartum or breastfeeding individuals. Breastfeeding increases calorie requirements by approximately 300–500 calories per day. Always consult your healthcare provider before starting a calorie deficit after pregnancy.

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