Protein and fat are two essential macronutrients your body needs every day. Protein supports muscle repair, immunity, and appetite control, while dietary fat helps absorb fat-soluble vitamins, supports hormones, and provides lasting energy. This Protein Fat Calculator turns your age, sex, height, weight, activity level, and goal into personalized daily gram targets for protein and fat — so you never have to rely on generic charts.
The calculator estimates your maintenance calories with the Mifflin-St Jeor equation, applies your chosen goal adjustment, then splits the calories into protein and fat based on your preferred intake settings. It also shows the calories and grams left for carbohydrates, giving you a complete daily framework.
Athletes, gym-goers, and anyone managing their weight can use these numbers as a practical starting point. Adjust the protein and fat settings to match your training style, and treat the output as a reference rather than a rigid prescription.
🥩 Protein & Fat Target Calculator
Estimate your daily protein and fat grams from your body stats, activity level, and goal.
📊 Your Daily Targets
How to Use This Tool
Using the Protein Fat Calculator takes about 30 seconds. Start by entering your age, sex, height, and current body weight — use the unit dropdowns to switch between cm/inches and kg/lb. Next, select the activity level that best represents your average week. Be honest here: “Moderate” means real, planned exercise 3–5 days per week, not just walking between meetings. Then pick your goal: fat loss, maintenance, or muscle gain. Finally, choose a protein target and a fat intake percentage that fit your eating style.
Click Calculate Targets and you will get your estimated daily calories plus gram and calorie targets for protein, fat, and the carbs left over. The step-by-step breakdown below the results shows exactly how the numbers were derived, which makes it easy to see what changes when you adjust a setting. Use the Reset button to return to the default example values.
How It Works (The Math Behind It)
The calculator uses the Mifflin-St Jeor equation, widely regarded as one of the most accurate predictive formulas for resting energy expenditure in healthy adults:
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
The basal metabolic rate (BMR) is the energy your body burns at complete rest. Multiplying BMR by an activity factor between 1.2 and 1.9 gives your total daily energy expenditure (TDEE) — the calories needed to hold your weight steady. A goal multiplier then converts this into a calorie target: 0.8 for a 20% deficit, 1.0 for maintenance, and 1.12 for a lean 12% surplus.
Protein grams are computed directly from body weight using your chosen factor (1.2–2.2 g per kg), and protein calories are calculated at 4 kcal per gram. Fat is a percentage of the calorie target at 9 kcal per gram. Whatever calories remain are assigned to carbohydrates at 4 kcal per gram. This “what’s left” approach keeps the three macronutrients balanced and makes the numbers easy to follow.
Worked Examples
BMR = (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 700 + 1093.75 − 150 + 5 = 1649 kcal
TDEE = 1649 × 1.375 ≈ 2267 kcal
Protein (1.6 g/kg) = 112 g → 448 kcal · Fat (30%) ≈ 680 kcal → 76 g · Carbs ≈ 1139 kcal → 285 g
BMR = (10 × 60) + (6.25 × 165) − (5 × 25) − 161 = 600 + 1031.25 − 125 − 161 = 1345 kcal
TDEE = 1345 × 1.55 ≈ 2085 kcal, then × 0.8 = 1668 kcal target
Protein (2.0 g/kg) = 120 g → 480 kcal · Fat (30%) ≈ 500 kcal → 56 g · Carbs ≈ 687 kcal → 172 g
Notice how the protein target stays anchored to body weight while fat scales with calories. That is intentional: protein needs are tied to lean mass preservation, especially during a deficit. The examples also show why body composition changes only when you combine a realistic calorie level with consistent training — the numbers simply set the framework.
Tips & Best Practices
- Round your targets to the nearest 5 grams for daily meal planning — exact grams are impractical to track.
- At least 0.8 g/kg is the minimum for general health; active people and those in a deficit will benefit from 1.6–2.2 g/kg.
- Keep fat at no less than 20% of calories to support hormone function and fat-soluble vitamin absorption, and no more than 40% unless you are deliberately following a low-carb plan.
- Weigh in consistently, ideally in the morning, and recalculate every 2–4 weeks as your weight moves.
Common Mistakes to Avoid
Another frequent issue is choosing a fat loss goal that is too aggressive. A 20% deficit is sustainable for most people; slashing calories by half is not. If the calculator warns that protein plus fat exceeds your target calories, lower the fat percentage or raise the calorie goal rather than dropping protein below 1.6 g/kg. Remember that the calculator is a starting estimate, not a medical prescription — if you have health conditions or are an athlete with unusual needs, consider working with a registered dietitian.
Reference Data
| Activity Level | Factor | Example |
|---|---|---|
| Sedentary | 1.2 | Desk job, minimal exercise |
| Light | 1.375 | 1–3 workouts per week |
| Moderate | 1.55 | 3–5 workouts per week |
| Active | 1.725 | 6–7 workouts per week |
| Athlete | 1.9 | Hard daily training / physical job |
| Protein Target | g/kg | Suitable For |
|---|---|---|
| Basic | 1.2 | Inactive adults, general health |
| Standard Fitness | 1.6 | Recreational athletes, most lifters |
| Athletic | 2.0 | Strength athletes, serious gym-goers |
| Bodybuilding | 2.2 | Bodybuilders in a cut or bulk |
Frequently Asked Questions
Is the Mifflin-St Jeor equation accurate? It is one of the most validated BMR formulas, but it is still an estimate. Individual results vary by body composition, genetics, and hormones. Track your weight for 2–3 weeks and adjust by roughly 100–200 kcal if needed.
Why are my carbs “remaining” instead of set? Because protein and fat are the priorities in this calculator, carbs fill in the leftover calories. This flexible approach works for most people, whether you prefer a moderate or lower-carb diet.
Do I need to eat my exact gram numbers every day? No. Targets are averages over the week, and day-to-day variation is completely normal. Consistency across days matters more than perfection on any single day.
Additional Resources
For deeper reading on protein needs and dietary fat, these evidence-based sources are a good starting point: