Enter your details to get a daily calorie target and estimated timeline for reaching your goal weight.
How the Weight Loss Calculator Works
Enter Age, Weight, Height & Goal
Calculate BMR (Mifflin-St Jeor)
Multiply by Activity Level for TDEE
Apply a Safe Calorie Deficit
Estimate Weeks to Goal Weight
What is a Weight Loss Calculator?
A Weight Loss Calculator determines the daily calorie intake needed to lose weight at a safe, sustainable rate by first calculating your Total Daily Energy Expenditure (TDEE) — the number of calories you burn in a day including activity — and then applying a moderate calorie deficit. Because fat loss fundamentally comes down to consistently consuming fewer calories than you burn, this calculator gives you a concrete, personalized number to work toward instead of vague advice like "eat less and move more."
Our free online weight loss calculator also estimates how long it will realistically take to reach your goal weight based on the size of your calorie deficit, helping you set an honest timeline rather than chasing crash-diet promises that are rarely sustainable or healthy.
How the Calculation Works
- Calculate BMR using the Mifflin-St Jeor formula:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161 - Calculate TDEE by multiplying your BMR by an activity multiplier ranging from 1.2 (sedentary) to 1.9 (extremely active).
- Apply a calorie deficit of approximately 500 calories per day, which corresponds to roughly 0.45 kg (1 lb) of fat loss per week, a rate widely considered safe and sustainable by health authorities.
- Estimate your timeline by dividing your total weight to lose by the expected weekly rate of loss.
Why a Moderate Deficit Beats a Crash Diet
Very aggressive calorie deficits often backfire. They tend to cause greater muscle loss alongside fat loss, slower metabolic rate adaptation, increased hunger and cravings, and a much higher risk of rebound weight regain once normal eating resumes. A moderate deficit of around 500 calories per day preserves more lean muscle mass, keeps energy levels more stable, and is far easier to sustain consistently — which matters more than any single week's rate of loss, since consistency over months is what actually produces lasting results.
| Deficit Size | Approx. Weekly Loss | Sustainability |
|---|---|---|
| 250 kcal/day | ~0.25 kg (0.5 lb) | Very sustainable, slower results |
| 500 kcal/day | ~0.45 kg (1 lb) | Balanced, widely recommended |
| 750–1000 kcal/day | ~0.7–0.9 kg (1.5–2 lb) | Harder to sustain long-term |
Activity Level Guide
| Activity Level | Description |
|---|---|
| Sedentary | Desk job, little to no structured exercise |
| Lightly Active | Light exercise 1–3 days per week |
| Moderately Active | Moderate exercise 3–5 days per week |
| Very Active | Hard exercise 6–7 days per week |
| Extremely Active | Physical job plus daily intense training |
Tips for Successful, Sustainable Weight Loss
- Prioritize protein: Higher protein intake helps preserve muscle mass and improves satiety during a deficit.
- Include resistance training: Strength training signals your body to retain muscle even while losing fat.
- Track progress with multiple metrics: Combine scale weight with waist-to-height ratio or body fat percentage for a fuller picture, since scale weight can fluctuate daily due to water and food volume.
- Recalculate every 10–15 lb lost: Your TDEE decreases as you lose weight, so periodically updating your calorie target keeps your deficit accurate.
- Avoid extreme restriction: Overly aggressive deficits raise the risk of nutrient deficiencies, muscle loss, and metabolic slowdown.
Limitations of This Calculator
This calculator provides population-level estimates based on validated formulas, but individual metabolic rates can vary by 10–15% due to genetics, muscle mass, hormonal factors, and other variables. Treat the calorie target and timeline as a starting point to adjust based on your real-world results over several weeks, rather than an exact guarantee.
Frequently Asked Questions
What is a safe rate of weight loss?
Most health guidelines recommend losing about 0.5 to 1 kg (1 to 2 lb) per week for sustainable, muscle-sparing fat loss.
Why isn't my weight loss matching the calculator's estimate?
Individual metabolic variation, water retention, hormonal cycles, and inconsistent tracking can all cause real-world results to differ from calculated estimates. Focus on trends over several weeks rather than daily fluctuations.
Should I eat back calories burned from exercise?
The activity multiplier in this calculator already accounts for your typical exercise level, so you generally don't need to add back exercise calories separately.
How often should I recalculate my calorie target?
Recalculate every 5–7 kg (10–15 lb) of weight lost, since your TDEE decreases as your body weight decreases.