Calculator Inputs
Formula Used
The calculator uses the Mifflin St Jeor equation for estimated BMR.
Male BMR = 10 × weight kg + 6.25 × height cm - 5 × age + 5.
Female BMR = 10 × weight kg + 6.25 × height cm - 5 × age - 161.
If body fat is entered, it also estimates Katch McArdle BMR.
Katch BMR = 370 + 21.6 × lean body mass in kg.
TDEE = selected BMR × activity multiplier + extra exercise calories.
Daily deficit = weekly loss target × 7700 ÷ 7.
Target calories = TDEE - deficit, adjusted by adherence and calorie floor.
Protein calories use 4 calories per gram. Fat uses 9. Carbohydrate uses 4.
How to Use This Calculator
- Select your unit system first.
- Enter age, height, current weight, and goal weight.
- Add body fat percent only if you know it.
- Choose your activity level honestly.
- Enter a realistic weekly weight loss target.
- Set macro preferences for protein and fat.
- Press the calculate button.
- Review calories, timeline, BMI, and macro targets.
- Use CSV or PDF buttons to save your plan.
Example Data Table
| Current Weight | Goal Weight | Activity | Weekly Loss | Estimated Daily Target |
|---|---|---|---|---|
| 85 kg | 75 kg | Light activity | 0.5 kg | About 1,900 calories |
| 95 kg | 82 kg | Moderate activity | 0.75 kg | About 2,150 calories |
| 180 lb | 165 lb | Sedentary | 0.4 kg | About 1,650 calories |
Weight Loss Planning Guide
Purpose
This calculator helps you estimate a daily calorie target for weight loss. It also shows maintenance calories, deficit size, BMI, goal timing, and macro targets. These values can help you build a simple food plan. They can also help you avoid random dieting.
Why Calories Matter
Weight loss usually needs a calorie deficit. This means your body uses more energy than you eat. The calculator first estimates resting energy use. Then it adds activity. The result is your estimated maintenance need. Your planned deficit is then subtracted from that number.
Activity Level
Activity has a large effect on results. Choose a level that matches your real week. Do not choose a higher level to force larger meals. That can slow progress. You can add extra exercise calories only when they are not already included in your activity level.
Goal Pace
A steady pace is easier to maintain. Many people prefer a modest weekly target. Faster loss may create hunger, fatigue, or poor training performance. The calculator marks the pace as moderate or aggressive. Use that note as a planning signal.
Macros
Protein supports fullness and lean mass. Fat supports hormones and meal satisfaction. Carbohydrates fill the remaining calories. This setup gives a balanced starting point. You can adjust macros based on appetite, culture, training, and food preference.
Tracking
Scale weight changes daily. Water, salt, sleep, and stress can hide fat loss. Compare weekly averages instead of one weigh in. Review your plan after two or three weeks. If weight does not move, reduce calories slightly or increase activity.
Safety
This tool gives estimates only. It is not medical advice. Very low calorie diets need professional guidance. People with illness, pregnancy, eating disorders, or medication concerns should speak with a qualified clinician before changing diet.
FAQs
1. What does this weight loss calculator estimate?
It estimates maintenance calories, deficit needs, goal calories, BMI, timeline, and basic macro targets. The numbers are planning estimates, not guaranteed outcomes.
2. Which formula is used for BMR?
It uses the Mifflin St Jeor equation. If body fat is supplied, it also uses the Katch McArdle method and averages both estimates.
3. What is a safe weekly weight loss target?
A moderate target is often near 0.5% to 1% of body weight weekly. Higher rates may be harder to sustain.
4. Why did my calorie target hit the floor?
The calculator raises the target when the deficit would push calories below your selected minimum. This helps avoid extreme recommendations.
5. Should I eat back exercise calories?
Only add exercise calories when they are not already represented by your activity level. Double counting can overestimate your calorie budget.
6. Why are carbs calculated last?
Protein and fat are set first. Remaining calories are assigned to carbohydrates because carbs are flexible and depend on preference and training.
7. How often should I update the calculation?
Update it after meaningful weight change, activity changes, or several weeks of stalled progress. Smaller bodies usually need fewer calories.
8. Is this calculator medical advice?
No. It is an educational planning tool. Ask a qualified professional before major diet changes, especially with health conditions.