Why Mifflin-St Jeor?
It is widely used for BMR estimates in healthy adults and pairs well with standard activity multipliers.
Weight Loss Calculator
Plan how many calories to eat and how long it may take to reach your goal weight.
Plan your weight loss
Enter your stats, activity, goal weight, and how many weeks you want to take.
About this calculator
How to use Weight Loss Calculator, plus the formulas and logic behind the results.
Tool description
This calculator estimates a daily calorie target from your BMR, activity level, and how fast you want to lose weight. It uses the common 7,700 kcal per kg of fat rule.
How to use
- Select metric or US units.
- Enter sex, age, height, current weight, and activity.
- Set your goal weight and timeline in weeks.
- Use the suggested calories as a starting point and adjust based on weekly scale trends.
Formulas & reference
BMR = Mifflin-St JeorTDEE = BMR × activity factorDaily deficit = (kg to lose × 7700) ÷ (7 × weeks)Target calories = TDEE − daily deficit (min 1200 kcal)
Safe loss pace
- 0.25–0.5 kg (0.5–1 lb) per week is typical for many adults
- Faster loss may suit medically supervised plans
- Protein and resistance training help preserve lean mass
Calculation logic
Total weight to lose is spread evenly across your timeline. The resulting deficit is subtracted from TDEE, with a floor of 1200 kcal/day for safety.
Very aggressive timelines can push calories too low. If the target hits 1200 kcal, extend your timeline or consult a clinician.
Weight Loss Calculator FAQ
Common questions about this calculator and how to use the results.
What if my goal is higher than current weight?
Use the Weight Gain Calculator instead—this tool is for loss planning only.
Is 1200 kcal a hard limit?
The calculator floors at 1200 kcal/day; many people need more, especially if very active.
Metric or US units?
Either works. Height, weight, and goal weight convert internally.
Do I need to hit calories exactly?
Treat the number as a starting target. Adjust ±100–200 kcal after 2–3 weeks of tracking.
Medical advice?
This is educational—not a substitute for personalized nutrition or medical care.