Calculator
Example Data Table
| Sex | Age | Height | Weight | Activity | Goal | Calories | Protein (g) | Fat (g) | Carbs (g) |
|---|---|---|---|---|---|---|---|---|---|
| Male | 28 | 178 cm | 78 kg | Moderately active | Cut (15%) | 2,350 | 150 | 70 | 270 |
| Female | 34 | 165 cm | 62 kg | Lightly active | Maintain | 1,950 | 110 | 55 | 240 |
Numbers above are illustrative examples for comparison.
Formula Used
- BMR (Mifflin-St Jeor): Male = 10W + 6.25H − 5A + 5, Female = 10W + 6.25H − 5A − 161 (W=kg, H=cm, A=years).
- BMR (Katch-McArdle): LBM = W × (1 − BF%), BMR = 370 + 21.6 × LBM.
- TDEE: TDEE = BMR × Activity Factor.
- Goal Calories: Cut/Bulk adjusts TDEE by percent or fixed kcal, Maintain uses TDEE, Custom uses your number.
- Macros: Protein and fat are set by your methods; carbs are remaining calories.
- Energy values: Protein = 4 kcal/g, Carbs = 4 kcal/g, Fat = 9 kcal/g.
- Fiber guide: ≈ 14 g per 1000 kcal (general guideline).
How to Use This Calculator
- Select your units, sex, age, height, and weight.
- Choose an activity level that matches most weeks.
- Pick a BMR method; add body fat % if available.
- Select your goal: cut, maintain, bulk, or custom calories.
- Set protein and fat methods, then choose values.
- Choose meals per day to see per-meal macro targets.
- Click Calculate to show results above the form.
- Use Download CSV or Download PDF to save your plan.
Energy Targeting and TDEE Inputs
IIFYM planning starts with a maintenance estimate. This calculator uses Mifflin‑St Jeor or Katch‑McArdle to estimate basal metabolic rate, then multiplies by an activity factor from 1.2 to 1.9. A 78 kg, 178 cm, 28‑year male at 1.55 activity may land near 2,700 kcal/day, while lighter profiles often fall closer to 1,900–2,200. Use this as a baseline for tracking.
Goal Adjustments for Cut, Maintain, Bulk
To change body weight, the calculator applies a controlled calorie shift. For cutting, a 10–25% reduction is common; bulking often uses a 5–15% increase to support training. You can also apply a fixed kcal adjustment for tighter control. Weekly averages matter more than single days, so targets are easy to revise.
Macro Allocation Logic and Practical Ranges
Protein and fat are set first, then carbohydrates fill the remainder. Protein can be entered as grams per kg, grams per lb, or a fraction of calories; many trainees start around 1.6–2.2 g/kg. Fats can be a percent of calories or grams per kg, with a body‑weight safety floor to avoid overly low intakes. Carbs then support performance and flexibility.
Meal Distribution and Consistency Tracking
The per‑meal split converts daily macros into workable targets across 1–10 meals. This helps align meals with schedules, fasting windows, or training sessions. Rounding to 1 g or 5 g reduces logging friction and makes meal templates easier to reuse. If rounding changes calories, the calculator shows the difference for transparency.
Export, Review, and Iteration
Macro targets work best as a feedback loop. Export results to CSV for spreadsheets or coaching check‑ins, and generate a simple PDF for offline reference. Re‑run the calculator after meaningful changes in body weight, activity, or training volume, or after two to three weeks of stable tracking. Small, data‑driven updates beat frequent overcorrections, with fewer surprises over time.
FAQs
What does IIFYM mean?
It means “If It Fits Your Macros”: you can include any foods if your daily protein, carbs, fats, and calories match your targets.
Which BMR method should I choose?
Use Mifflin‑St Jeor if you do not know body fat %. Choose Katch‑McArdle when you have a reliable body fat estimate, because it accounts for lean body mass.
Why did my carbs become very low or zero?
If protein and fat settings consume most calories, there is little remaining energy for carbs. Lower fat %, lower protein, or raise calories until carbs fit your preferences and training needs.
How often should I update my targets?
Update after noticeable weight change, activity changes, or when progress stalls for 2–3 weeks. Use weekly average scale weight and training performance to guide small adjustments.
Do I need to hit macros perfectly every day?
No. Aim for consistency across the week. Many people use a ±5–10 g window for macros and focus on calorie accuracy, adequate protein, and sustainable habits.
What does the rounding option do?
Rounding simplifies tracking by nudging grams to neat values (1 g or 5 g). The calculator shows the calorie difference after rounding so you can decide whether to keep or adjust the plan.