Reweight Calculator
Safe weight loss is typically 0.25–0.5 kg/week. Max sustainable: ~1 kg/week.
Reweight Calculator — Guide & Formula
The Reweight Calculator tells you how many weeks and days it will take to reach your target weight at a given weekly rate of loss or gain. It also estimates the required daily calorie deficit or surplus.
Formula
- Total change = |current weight − target weight| (kg)
- Weeks to goal = total change ÷ weekly rate
- Daily calorie deficit/surplus = weekly rate × 7,700 ÷ 7
What is 7,700 kcal per kg?
Pure fat tissue contains approximately 9 kcal per gram (9,000 kcal/kg), but body weight change is a mix of fat, water, and lean tissue. An average effective caloric value of ~7,700 kcal per kg of body weight change is widely used in clinical and dietary practice.
Safe rate of weight loss
| Rate | Daily deficit | Notes |
|---|---|---|
| 0.25 kg/week | ~275 kcal/day | Very gradual, highly sustainable |
| 0.5 kg/week | ~550 kcal/day | Standard recommendation — sustainable |
| 0.75 kg/week | ~825 kcal/day | Moderate, requires discipline |
| 1 kg/week | ~1,100 kcal/day | Aggressive — may risk muscle loss |
Tips for reaching your goal
- Combine calorie reduction with regular physical activity
- Prioritise protein intake (1.6–2.2 g/kg body weight) to preserve muscle
- Track progress weekly, not daily (daily weight fluctuates 1–2 kg due to water)
- Losing more than 1 kg/week typically results in significant muscle loss
References
- Hall KD et al. (2011). "Quantification of the effect of energy imbalance on bodyweight." Lancet 378(9793):826–837.
- Stiegler P, Cunliffe A (2006). "The role of diet and exercise for the maintenance of fat-free mass." Sports Med 36(3):239–262.
See Also
- 90 kg to 80 kg at 0.5 kg/week
- 85 kg to 75 kg at 0.5 kg/week
- 80 kg to 70 kg at 0.5 kg/week
- 100 kg to 85 kg at 0.75 kg/week
- 75 kg to 65 kg at 0.5 kg/week
- 70 kg to 60 kg at 0.5 kg/week
- 95 kg to 80 kg at 1 kg/week
- 110 kg to 90 kg at 0.75 kg/week
- 65 kg to 60 kg at 0.25 kg/week
- 60 kg to 55 kg at 0.5 kg/week
