Macronutrient Calculator | Macros
Calculate your daily protein, carbohydrate, and fat targets based on your TDEE and goals.
Quick Presets
Step 1, Body Stats
Step 2, Activity Level
BMR Formula
Step 3, Goal
Enter key calculates · Escape resets
What Is the Macronutrient Calculator | Macros?
This calculator takes you through three steps: body stats (sex, age, weight, height) to compute BMR and TDEE, activity level to multiply BMR, and goal selection to adjust calories up or down. Macro targets in grams are then derived from the calorie total based on goal-appropriate ratios.
- ›Two BMR formulas, Mifflin-St Jeor (recommended; validated in 2005 meta-analysis) and Harris-Benedict (revised 1984). Both shown for comparison.
- ›Five activity levels, sedentary to extra active, each with a standard multiplier (×1.2 to ×1.9).
- ›Five goal presets, aggressive cut (−500 kcal), moderate cut (−250), maintenance, lean bulk (+250), aggressive bulk (+500).
- ›Goal-appropriate macro splits, protein percentage is highest in cuts to preserve muscle; carbs higher in bulks for fuel.
- ›Visual macro bars, percentage distribution shown as colour-coded progress bars.
- ›Food source suggestions, three example foods per macro category.
- ›Step-by-step working, collapsible panel showing every BMR, TDEE, and macro calculation step.
- ›localStorage persistence, your last inputs are restored automatically.
Formula
Mifflin-St Jeor BMR (recommended)
Male: BMR = 10W + 6.25H − 5A + 5
Female: BMR = 10W + 6.25H − 5A − 161
Harris-Benedict BMR (revised 1984)
Male: BMR = 88.362 + 13.397W + 4.799H − 5.677A
Female: BMR = 447.593 + 9.247W + 3.098H − 4.330A
TDEE and Calorie Target
TDEE = BMR × activity factor
Target = TDEE + goal adjustment
Macro Calories
Protein: 4 kcal per gram
Carbohydrate: 4 kcal per gram
Fat: 9 kcal per gram
| Symbol | Name | Description |
|---|---|---|
| W | Weight (kg) | Body weight in kilograms |
| H | Height (cm) | Standing height in centimetres |
| A | Age (years) | Age in years (15–100) |
| BMR | Basal Metabolic Rate | Calories burned at complete rest per day |
| TDEE | Total Daily Energy Expenditure | BMR × activity factor, total daily calories burned |
How to Use
- 1Load a preset or enter stats: Click a Quick Preset (Active Male 80 kg, Active Female 60 kg, Athlete 90 kg) or enter sex, age, weight, and height manually.
- 2Choose weight and height units: Toggle between kg/lbs and cm/ft·in using the unit buttons next to each input.
- 3Select activity level: Pick the activity level that best describes your typical week, sedentary, lightly active, moderately active, very active, or extra active.
- 4Choose a BMR formula: Mifflin-St Jeor is the default and is validated by a 2005 meta-analysis. Harris-Benedict is also shown for comparison. Both results appear in the output.
- 5Select your goal: Choose from Aggressive Cut (−500 kcal), Moderate Cut (−250), Maintenance, Lean Bulk (+250), or Aggressive Bulk (+500).
- 6Press Enter or click Calculate Macros: Results show your BMR (both formulas), TDEE, target calories, and daily grams of protein, carbs, and fat with percentages.
- 7Review the step-by-step working: Expand the collapsible panel to see every intermediate calculation including the exact BMR formula substitution.
Example Calculation
Active male, 28 years, 80 kg, 178 cm, Lean Bulk goal
Step 1: Mifflin-St Jeor BMR (male)
BMR = 10×80 + 6.25×178 − 5×28 + 5
= 800 + 1112.5 − 140 + 5
= 1777.5 kcal/day
Step 2: TDEE (moderately active ×1.55)
TDEE = 1777.5 × 1.55 = 2755 kcal/day
Step 3: Goal adjustment (Lean Bulk +250 kcal)
Target = 2755 + 250 = 3005 kcal/day
Step 4: Macro split (Lean Bulk: 25% P / 45% C / 30% F)
Protein: 3005 × 25% ÷ 4 = 188 g
Carbs: 3005 × 45% ÷ 4 = 338 g
Fat: 3005 × 30% ÷ 9 = 100 g
Result: 188g protein / 338g carbs / 100g fat = 3004 kcal
| Goal | Calorie Adj | Protein | Carbs | Fat |
|---|---|---|---|---|
| Aggressive Cut | −500 kcal | 40% | 30% | 30% |
| Moderate Cut | −250 kcal | 35% | 35% | 30% |
| Maintenance | 0 kcal | 30% | 40% | 30% |
| Lean Bulk ★ | +250 kcal | 25% | 45% | 30% |
| Aggressive Bulk | +500 kcal | 25% | 50% | 25% |
Protein: the non-negotiable macro
During a calorie deficit, high protein intake (35–40% of calories) preserves lean muscle mass. Research shows ~1 g per pound of bodyweight (2.2 g/kg) as an effective upper target for athletes. At 80 kg (176 lbs), this means up to 176 g protein per day during a cut.
Understanding Macronutrient | Macros
BMR Formulas, Which to Use?
The Mifflin-St Jeor equation (1990) is the most validated formula for estimating resting metabolic rate in healthy adults. A 2005 meta-analysis of 60 studies found it to be within ±10% for most adults and more accurate than the Harris-Benedict formula, especially for overweight individuals.
The Harris-Benedict equation (revised 1984) is older but still widely used in clinical settings. It tends to overestimate BMR by 5–15% compared to measured values. Both results are shown so you can see the range.
- ›If your two BMR estimates differ by more than 200 kcal, the lower estimate is usually more accurate.
- ›BMR formulas assume you are at complete rest in a thermoneutral environment, actual RMR during light daily activity is always higher.
- ›Body composition matters: muscle burns more calories than fat. BMR formulas use bodyweight, not lean mass, so leaner individuals may have a higher actual BMR than predicted.
Activity Multipliers (Harris-Benedict Scale)
| Level | Multiplier | Typical Profile |
|---|---|---|
| Sedentary | ×1.2 | Desk job, little or no exercise |
| Lightly active | ×1.375 | Light exercise 1–3 days/week |
| Moderately active | ×1.55 | Moderate exercise 3–5 days/week |
| Very active | ×1.725 | Hard exercise 6–7 days/week |
| Extra active | ×1.9 | Physical job + training, or twice-daily training |
Understanding the Three Macronutrients
- ›Protein (4 kcal/g), essential for muscle repair and synthesis, immune function, enzymes, and hormones. Sources: chicken, eggs, fish, legumes, dairy, tofu. Recommended: 1.6–2.2 g/kg for athletes (Academy of Nutrition and Dietetics).
- ›Carbohydrates (4 kcal/g), the preferred fuel for the brain and high-intensity exercise. Includes simple sugars and complex starches. Fibre (a carb) is not digested and contributes negligible calories. Sources: rice, oats, fruit, vegetables, bread.
- ›Fat (9 kcal/g), required for fat-soluble vitamin absorption (A, D, E, K), hormone production, and cell membrane integrity. Sources: olive oil, avocado, nuts, salmon, eggs. Minimum 20% of calories is recommended to avoid hormonal disruption.
The 500-calorie rule for weight change
One pound (0.45 kg) of body fat contains approximately 3,500 kcal. A sustained deficit of 500 kcal/day theoretically produces ~0.5 kg of fat loss per week. In practice, metabolic adaptation and water weight mean actual loss may differ. A moderate deficit of 250–500 kcal/day is generally recommended to minimise muscle loss.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest, essentially just to stay alive (breathing, circulation, temperature regulation).
TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to account for all movement during the day. It represents your total calorie burn.
- ›BMR is the floor, you cannot consume fewer calories than this long-term without metabolic damage.
- ›TDEE is your maintenance level, eating at TDEE keeps weight stable.
- ›Calorie deficits and surpluses are calculated relative to TDEE, not BMR.
Which BMR formula is more accurate, Mifflin or Harris-Benedict?
A 2005 meta-analysis of 60 studies found the Mifflin-St Jeor equation to be the most accurate for the general population, within ±10% of measured RMR for 82% of subjects.
The Harris-Benedict equation (revised 1984) tends to overestimate BMR by 5–15%. It was derived from a less diverse sample and is considered slightly less accurate for modern populations.
Both formulas are shown in the results, treat the output as an estimate and adjust based on real-world weight changes over 2–3 weeks.
How much protein do I need per day?
Protein recommendations vary by goal:
- ›General health: 0.8 g/kg bodyweight (WHO minimum)
- ›Fat loss: 1.6–2.0 g/kg to preserve muscle during a calorie deficit
- ›Muscle gain: 1.6–2.2 g/kg (Academy of Nutrition and Dietetics)
- ›Athletes: up to 2.2 g/kg (roughly 1 g/lb of bodyweight)
Higher protein intakes (2.2+ g/kg) are safe for healthy adults but provide diminishing returns for muscle synthesis beyond ~2.2 g/kg.
What macro split should I use for weight loss?
For fat loss, the most important factor is the calorie deficit, not the exact macro split. That said, a higher protein ratio helps preserve muscle:
- ›Moderate cut: 35% protein / 35% carbs / 30% fat, balanced and sustainable
- ›Aggressive cut: 40% protein / 30% carbs / 30% fat, prioritises muscle preservation
- ›Low-carb: 35% protein / 20% carbs / 45% fat, reduces insulin, some find it satiating
Protein is the most satiating macro and has the highest thermic effect of food (25–30% of protein calories are used in digestion), making it doubly useful in a cut.
What is the best macro ratio for building muscle?
For muscle gain, a slight calorie surplus combined with adequate protein and carbohydrates works best:
- ›Lean bulk: 25% protein / 45% carbs / 30% fat (recommended)
- ›Protein: 1.6–2.2 g/kg, enough for muscle protein synthesis; more than this shows diminishing returns
- ›Carbs: higher carb intake provides glycogen for training and supports insulin (anabolic hormone)
- ›Fat: minimum 20–25% to support testosterone and hormonal health
A lean bulk surplus of +250 kcal/day minimises fat gain. More aggressive surpluses increase fat gain without proportionally faster muscle growth.
How many calories do I need per day?
Your daily calorie need (TDEE) depends on sex, age, weight, height, and activity level. Typical ranges:
- ›Sedentary woman (65 kg): ~1,700–1,900 kcal/day
- ›Moderately active woman (65 kg): ~2,000–2,200 kcal/day
- ›Sedentary man (80 kg): ~2,100–2,400 kcal/day
- ›Moderately active man (80 kg): ~2,600–3,000 kcal/day
- ›Highly active athlete (90 kg): ~3,200–4,000 kcal/day
Use this calculator to get a personalised estimate based on your inputs, then track weight for 2–3 weeks to calibrate.
Are the macro percentages fixed, or can I adjust them?
This calculator uses evidence-based preset splits per goal (e.g., 25/45/30 for lean bulk). These are starting points, not rigid rules. Individual adjustments you might make:
- ›Higher protein: if you feel you need more to recover or if you are very lean and cutting
- ›Higher carbs: if you do high-intensity exercise (CrossFit, sprinting, weightlifting)
- ›Higher fat: if you follow a low-carb or paleo-style approach
- ›Lower fat: if you prefer a high-carb performance diet (common in endurance sports)
The minimum recommended fat intake is ~20% of calories to avoid hormonal issues. Protein rarely needs to exceed 35% unless in a very aggressive cut.
Does the calculator save my inputs?
Yes, all inputs are saved to your browser's localStorage after each calculation and restored when you return. Click Reset to clear all fields and remove saved data. Nothing is sent to any server.