Calculator Inputs
Example Data Table
| Profile | BMR formula | Activity | Deficit plan | Likely target |
|---|---|---|---|---|
| 82 kg male, 35, 175 cm | Mifflin St Jeor | Light | 0.5 kg/week | About 2,000 kcal/day |
| 70 kg female, 30, 165 cm | Mifflin St Jeor | Moderate | 20 percent | About 1,650 kcal/day |
| 200 lb male, 42, 5 ft 10 in | Harris Benedict | Sedentary | 500 kcal/day | About 1,900 kcal/day |
| 60 kg athlete, 28, 22% fat | Katch McArdle | Very active | 0.25 kg/week | About 2,150 kcal/day |
Formula Used
Mifflin St Jeor for men: BMR = 10 × weight kg + 6.25 × height cm − 5 × age + 5.
Mifflin St Jeor for women: BMR = 10 × weight kg + 6.25 × height cm − 5 × age − 161.
Revised Harris Benedict for men: BMR = 88.362 + 13.397 × weight kg + 4.799 × height cm − 5.677 × age.
Revised Harris Benedict for women: BMR = 447.593 + 9.247 × weight kg + 3.098 × height cm − 4.330 × age.
Katch McArdle: BMR = 370 + 21.6 × lean body mass kg.
Total daily energy expenditure: TDEE = BMR × activity factor + weekly exercise calories ÷ 7.
Calorie target: Target = TDEE − planned daily deficit. The calorie floor is applied when needed.
Weight change estimate: Weekly loss kg = daily deficit × 7 ÷ 7700. Weekly loss lb = daily deficit × 7 ÷ 3500.
Macro formulas: protein calories = protein grams × 4. Fat calories = fat grams × 9. Carb grams use remaining calories ÷ 4.
How to Use This Calculator
- Select metric or imperial units.
- Enter age, height, current weight, and target weight.
- Choose the formula that best matches your available data.
- Select an activity factor that reflects an average week.
- Pick a deficit mode: goal rate, percent, or manual calories.
- Set a calorie floor, protein target, fat percentage, and meal count.
- Press the calculate button. Review the result above the form.
- Download the CSV or PDF summary for later planning.
Calories Needed to Lose Weight
A weight loss calorie plan starts with energy balance. Your body uses energy for breathing, digestion, movement, and training. This calculator estimates that daily need first. Then it subtracts a selected deficit. The result is a practical calorie target for gradual fat loss.
Estimate Your Base Need
The first step is basal metabolic rate. BMR is the energy used at rest. The Mifflin St Jeor method works well for most adults. The revised Harris Benedict method gives another view. The Katch McArdle method can help when body fat percentage is known.
The second step is total daily energy expenditure. TDEE multiplies BMR by an activity factor. A desk job uses a lower factor. Active work and planned exercise use higher factors. You can also enter weekly exercise calories. The tool spreads those calories across seven days.
Choose a Deficit
The third step is the deficit. A small deficit is easier to keep. A larger deficit may work faster, yet it is harder. The calculator supports goal rate, percent deficit, and manual deficit modes. This helps match different planning styles.
A useful goal is usually steady. Many people choose about half a kilogram per week. Some choose one pound per week. The tool converts your goal into calories. It uses the idea that one kilogram of fat stores about 7700 calories. One pound stores about 3500 calories.
Check Safety and Macros
Safe floors matter. Very low calorie targets can reduce energy, mood, training quality, and nutrient intake. The calculator includes a minimum calorie setting. It also flags very aggressive deficits. These warnings are planning guides. They are not medical advice.
Macronutrients make the target easier to use. Protein helps preserve lean mass. Fat supports hormones and satiety. Carbohydrates fill the remaining calories. You can choose protein by body weight. You can set fat as a percentage. The calculator then estimates grams for each macro.
Meal planning can also help. The meal count option divides daily calories into equal meals. This is not required. It simply gives a quick starting point. You may eat fewer or more meals. The best pattern is the one you can repeat.
Track and Adjust
The timeline estimate is only an estimate. Water weight can change quickly. Sodium, stress, sleep, and training can shift scale weight. Use weekly averages instead of one weigh in. Adjust the target after two or three weeks if progress stalls.
For better results, combine the calorie target with simple habits. Track food honestly. Eat high protein meals. Include fiber rich foods. Lift weights when possible. Walk more during the day. Sleep enough. Consistency turns the calculation into progress.
Use measurements with care. Height, weight, age, and sex affect the estimate. Activity choices can be overestimated. Start with the option that matches an average week, not your hardest day. Review energy, hunger, gym performance, and mood. If the plan feels impossible, reduce the deficit. Sustainable targets beat perfect numbers and supports healthier long term change without burnout.
FAQs
How many calories should I eat to lose weight?
Your target depends on BMR, activity, exercise, and deficit size. Many plans use a 250 to 750 calorie daily deficit. This calculator estimates a personal target and shows warnings when the deficit looks aggressive.
Which BMR formula should I choose?
Mifflin St Jeor is a good default for most adults. Harris Benedict gives a second estimate. Katch McArdle is useful when you know body fat percentage because it uses lean body mass.
What is TDEE?
TDEE means total daily energy expenditure. It estimates all calories you burn in a day. It includes resting needs, daily movement, and planned exercise. Your calorie target is usually below this number.
Is a 500 calorie deficit best?
A 500 calorie deficit is common, but it is not best for everyone. Smaller bodies may need less. Very active people may handle more. Adherence, recovery, and hunger matter.
Why does the calculator use a calorie floor?
A calorie floor prevents very low targets from appearing as normal plans. Low intake can make nutrition harder. It can also reduce energy and training quality. Use professional guidance for strict diets.
How accurate is the weight loss timeline?
The timeline is an estimate. It assumes the same deficit continues. Real progress changes with water balance, digestion, adherence, and metabolic adaptation. Use it for planning, not exact prediction.
Should I include exercise calories?
Enter exercise calories only when they are not already reflected in your activity factor. Double counting can inflate TDEE. When unsure, keep activity conservative and adjust using real progress.
How much protein should I use?
Many weight loss plans use about 1.6 to 2.2 grams per kilogram of body weight. Higher protein may support fullness and lean mass. Personal needs can vary.
Can I use imperial units?
Yes. Choose imperial units. Enter feet, inches, pounds, and a weekly loss goal in pounds. The calculator converts those values internally for the formulas.
Why are carbs calculated last?
Protein and fat targets are set first because they support structure and satiety. Carbohydrates receive the remaining calories. You can change protein or fat settings to adjust carb grams.
When should I adjust my calories?
Review weekly weight averages after two or three weeks. Adjust only when progress clearly stalls. Small changes become powerful when repeated every single week.