Fat Loss Calorie Calculator

Find targets for cutting, maintenance, and protein planning. Adjust activity, deficits, and goal timelines easily. Build sustainable fat loss plans with clearer intake numbers.

Calculator Inputs

Unit system

Sex

Age

Height (cm)

Current weight (kg)

Goal weight (kg)

Activity level

Body fat % (optional)

Needed for Katch-McArdle and lean-mass protein settings.

Metabolic formula

Deficit mode

Weekly loss target (kg/week)

Protein multiplier (g/kg)

Fat multiplier (g/kg)

Protein basis

Example Data Table

Profile	Sex	Age	Height	Weight	Goal	Activity	Deficit	Target Calories	Macros
Office worker cut	Male	32	178 cm	88 kg	80 kg	Moderate	0.50 kg/week	2,298 kcal/day	160g P / 64g F / 271g C
Lean mass guided cut	Female	29	165 cm	72 kg	66 kg	Light	20% TDEE	1,590 kcal/day	132g P / 53g F / 147g C

Formula Used

Mifflin-St Jeor BMR: Men: 10W + 6.25H − 5A + 5. Women: 10W + 6.25H − 5A − 161. Here, weight is kilograms, height is centimeters, and age is years.

Katch-McArdle BMR: 370 + 21.6 × lean body mass. Lean body mass equals weight × (1 − body fat % / 100).

Total Daily Energy Expenditure: TDEE = BMR × activity factor.

Daily deficit from weekly target: (weekly loss in kg × 7700) ÷ 7.

Daily deficit from percentage: TDEE × deficit %.

Target calories: TDEE − daily deficit.

Macro split: Protein calories = grams × 4, carbohydrate calories = grams × 4, fat calories = grams × 9. Carbohydrates receive the remaining calories after protein and fat.

How to Use This Calculator

Choose metric or imperial units.
Enter age, sex, height, current weight, and goal weight.
Select the activity level that best matches your normal week.
Optionally add body fat percentage for lean-mass calculations.
Pick either an expected weekly loss rate or a TDEE percentage deficit.
Set protein and fat multipliers to match your nutrition approach.
Press calculate to see calories, macros, timeline, and warning flags.
Use the CSV or PDF buttons to save your result summary.

Frequently Asked Questions

1. Which calorie formula should I choose?

Use auto for convenience. It selects Katch-McArdle when body fat is available, otherwise Mifflin-St Jeor. Mifflin works well for most adults, while Katch can better reflect leaner physiques.

2. What is a reasonable weekly fat loss target?

Many people aim for about 0.25 to 1.00 kilograms weekly. Slower targets often preserve training quality, hunger control, and adherence better than very aggressive cuts.

3. Why does the calculator show warnings?

Warnings appear when calories drop below a common reference floor, below estimated BMR, or when the projected rate becomes aggressive. They highlight sustainability concerns, not diagnosis.

4. Why are carbohydrates sometimes very low?

Carbs receive whatever calories remain after protein and fat are assigned. Raising protein or fat multipliers can shrink carbs quickly, especially during aggressive deficits.

5. Should I base protein on current, goal, or lean weight?

Goal weight works well for most cuts. Current weight can suit larger athletes. Lean mass can be useful when body fat is known and you want a more individualized protein target.

6. Is the estimated timeline exact?

No. Real progress changes with water balance, adherence, training load, menstrual cycle, stress, and metabolic adaptation. Treat the timeline as a planning estimate.

7. Can I use this during muscle gain phases?

This page is tuned for fat loss. You can still use the BMR and TDEE estimates, but calorie and macro targets should be adjusted upward for gaining phases.

8. Does the calculator replace professional nutrition advice?

No. It gives structured estimates. People with medical conditions, pregnancy, eating disorders, or prescribed diets should use guidance from a qualified clinician or dietitian.