Weight Loss Calculator
Plan weight loss with a daily calorie target, weekly deficit and exercise minutes, then see the estimated timeline to your goal.
Your goal weight — must be below your current weight.
0.25-1 kg per week is a sustainable, commonly recommended pace.
Daily calories to reach target
2,345 kcal
TDEE 2,895 − deficit 550 kcal
Estimated time to goal
20 weeks
≈ 140 days at 0.5 kg/week
Total to lose
10 kg
7,700 kcal per kg
BMR (Mifflin-St Jeor)
1,868 kcal
Calories at complete rest
Calorie-balance model using the Mifflin-St Jeor equation. Estimates only — real losses vary with adherence, muscle changes and metabolic adaptation. Talk to a doctor before starting any weight-loss plan.
Last updated: January 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
The weight loss calculator turns the calorie-balance model into a personal plan: a daily target, a deficit and a realistic horizon. People preparing for events, weddings or medical targets use it to see whether their goal is achievable at a healthy pace or needs more time. Those starting a fitness programme use it alongside the protein and macro calculators to make sure the deficit does not cost them muscle. Dietitians and trainers use the timeline to set expectations and recheck points, since the model assumes steady adherence. Because the tool refuses targets below 1,000 kcal, it quietly steers extreme dieters toward a safer pace. Like all estimates it assumes the activity factor is honest — over-reporting activity is the most common reason real results lag the plan, so most users learn to trust the scale trend over several weeks.
How to Use This Calculator
- Step 1: Choose a plan approach — Calorie target for a daily calorie goal, or Exercise time to see how much activity covers the same deficit.
- Step 2: Select your sex and enter your current weight; in calorie mode also enter your height, age and activity level.
- Step 3: Set a target weight below your current weight and pick a weekly loss rate between 0.25 and 1 kg.
- Step 4: In exercise mode choose an activity and session length, then read the minutes per week needed, the sessions required and the estimated time to goal.
Worked Example
A moderately active 30-year-old man weighing 90 kg at 178 cm has a Mifflin-St Jeor BMR of about 1,868 kcal, giving a TDEE of about 2,895 kcal at the 1.55 activity factor. Targeting 80 kg at 0.5 kg per week means a daily deficit of 550 kcal — 3,850 kcal a week, since 1 kg of body fat holds about 7,700 kcal. His daily calorie target is therefore about 2,345 kcal. With 10 kg to lose, the plan estimates roughly 140 days, or about 20 weeks. The same weekly deficit needs about 965 minutes of moderate walking, far fewer of a higher-MET sport like running.
Tips and Common Mistakes
- •Tip 1: Aim for 0.5-1 kg per week — faster rates usually shed water and muscle, not fat.
- •Tip 2: Eat 1.6-2.2 g of protein per kg of body weight to protect muscle during the deficit.
- •Tip 3: Recalculate every 3-4 kg lost, since TDEE falls as you shrink.
- ✗Mistake 1: Drastically cutting below the suggested target; very low intakes invite muscle loss and rebound hunger.
- ✗Mistake 2: Chasing the timeline too literally — plateaus are normal, so judge progress on weekly averages.
Expert Note
1 kg of body fat contains approximately 7,700 kcal. The safe rate of weight loss is 0.5-1 kg per week, requiring a daily deficit of 550-1,100 kcal. Below 1,000 kcal/day for men and 800 kcal/day for women, medical supervision is recommended. The TDEE decreases as weight is lost — recalculate every 3-4 kg.
Sources and References
- •Mifflin-St Jeor equation — American Dietetic Association
- •NIH Body Weight Planner — National Institutes of Health
- •WHO: Physical activity and energy expenditure guidelines
Official sources are linked so you can confirm the current rate yourself. Check the linked page for the latest notification before relying on these figures.
Frequently Asked Questions
How is my daily calorie target calculated?
The calculator estimates BMR with the Mifflin-St Jeor equation, multiplies it by your activity factor to get TDEE, then subtracts the deficit implied by your weekly loss rate — about 550 kcal per day for 0.5 kg per week, since 1 kg of body fat holds roughly 7,700 kcal.
Is 0.5 kg per week a safe rate of weight loss?
Yes — 0.5-1 kg per week is the commonly recommended sustainable range for most adults. Faster loss often comes from water and muscle rather than fat, and sharply restricted diets are harder to maintain and more likely to rebound.
Why do I need to eat more than 1,000 kcal even when dieting?
Very low intakes risk muscle loss, nutrient deficiencies and a slowing metabolism. The calculator refuses targets below 1,000 kcal — if your numbers go that low, a slower loss rate or a modest increase in activity is the healthier adjustment.
How accurate is the estimated timeline to my goal?
The timeline assumes the deficit is achieved every day and that all weight lost is fat, which is never perfectly true. Plateaus, water shifts and metabolic adaptation mean real timelines run longer — treat the estimate as a minimum, not a promise.
Should I focus only on calories, or also on what I eat?
Calories set the direction, but food quality decides how you feel while losing. A higher-protein, fibre-rich diet preserves muscle, keeps you full and protects micronutrients. Losing weight on empty calories leaves you hungry and prone to quitting.
When should I see a doctor before dieting?
If you have diabetes, heart or kidney disease, are pregnant or nursing, take regular medication, or plan to lose a large amount of weight, check with a doctor first. The same applies if you are under 18 or have a history of disordered eating.
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