Weight Loss Calculator
See exactly when you'll reach your goal — with a visual timeline, milestones, and meal ideas.
100% free. No signup required.
This calculator provides estimates for educational purposes only and is not medical advice. Actual weight loss varies based on individual metabolism, adherence, and other factors.
How this calculator works
Unlike simple calculators that assume you lose weight at a constant rate, we simulate your journey week by week. Your body burns fewer calories as you get lighter - so we recalculate your TDEE at every step using the Mifflin-St Jeor equation, the most accurate published formula for most adults. We also never plan an intake below your estimated resting metabolism or the 1,200 cal (women) / 1,500 cal (men) guideline floor. The interactive chart shows how your weight drops over time, with milestones to keep you motivated along the way.
Use the deficit slider to find your sweet spot between speed and sustainability. Add your body fat percentage to see how much fat vs. lean mass you'll lose. Toggle the comparison mode to see how increasing your activity level could shorten your timeline.
Once you have your calorie target, find your ideal protein/carb/fat split or browse low-calorie recipes to start building your meals.
Frequently asked questions
How long does it take to lose 10 kg?
It depends on your starting weight, because the evidence-supported rate is 0.5-1% of body weight per week - this calculator sizes your deficit to that rate, between 250 and 750 calories per day. At about 0.45 kg (1 lb) per week, losing 10 kg takes roughly 22 weeks (about 5.5 months). A milder deficit takes longer but is more sustainable, while an aggressive deficit is faster but harder to maintain and may lead to muscle loss.
What is a safe rate of weight loss?
The evidence supports losing 0.5-1% of your body weight per week - for most people that is a daily calorie deficit of roughly 250-750 calories. Losing weight faster than this often means you are losing muscle along with fat, and it is harder to sustain long-term. Slow, steady weight loss is more likely to stay off.
How many calories should I cut to lose weight?
Size your deficit at 0.5-1% of your body weight per week - for most people that is roughly 250-750 calories per day below your Total Daily Energy Expenditure (TDEE), the calories you burn daily. This calculator never plans an intake below your estimated resting metabolic rate or the 1,200 calorie (women) / 1,500 calorie (men) guideline floor. The BMR line is not a physiological limit - but the estimate itself carries around 150 calories of error, and eating under it makes muscle loss and nutrient shortfalls more likely.
Why does weight loss slow down over time?
As you lose weight, your body requires fewer calories to function (lower TDEE). This means the same calorie intake that created a deficit initially becomes closer to maintenance. This is called metabolic adaptation. To continue losing, you may need to slightly reduce calories or increase activity. Our calculator accounts for this by recalculating TDEE as your weight decreases.
Is a 1000 calorie deficit safe?
For most people, no - a 1000 calorie deficit exceeds the evidence-supported rate of 0.5-1% of body weight per week and often costs muscle along with fat. This calculator caps the deficit at 750 calories per day, and lower for lighter bodies. A 500 calorie deficit is a sustainable starting point for most people. If you have significant weight to lose, consult a healthcare provider about an appropriate deficit level.
Formulas and scientific references Mifflin-St Jeor equation (1990) for calories, with the deficit sized at 0.5-1.0% of body weight per week rather than a flat 500 kcal, and floored at estimated resting metabolic rate.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990;51(2):241-247
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 2005;105(5):775-789
- Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism, 2011;21(2):97-104
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition, 2014;11:20
- Fothergill E, Guo J, Howard L, et al. Persistent metabolic adaptation 6 years after "The Biggest Loser" competition. Obesity, 2016;24(8):1612-1619
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Why the static 3,500 kcal per pound rule overstates long-term weight loss. The Lancet, 2011;378(9793):826-837
This calculator gives a general educational estimate, not medical or individualized nutrition advice. Prediction equations are wrong by more than 10% in roughly 1 in 3 people.