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IIFYM Calculator

Health

Calculate your IIFYM macro targets — protein set by bodyweight, fat as a percentage of calories, and carbs filling the rest — based on your TDEE and goal.

Reviewed by the thecalcu.com team · Last updated July 25, 2026

1580
30200
100250

Daily Calories

2,250
Protein (g/day)
154
Fat (g/day)
63
Carbs (g/day)
267
TDEE — Maintenance Calories
2,250

This calculator computes your Daily Calories, Protein (g/day), Fat (g/day), Carbs (g/day), TDEE — Maintenance Calories from the values you enter.

Inputs
GenderAgeWeightHeightActivity LevelGoal
Outputs
Daily CaloriesProtein (g/day)Fat (g/day)Carbs (g/day)TDEE — Maintenance Calories

What is a IIFYM?

An IIFYM Calculator determines your daily macronutrient targets, protein, fat, and carbohydrates, using the "If It Fits Your Macros" method popularized in flexible dieting and bodybuilding communities. Unlike calculators that split calories into fixed percentages for all three macros, the IIFYM method sets protein first based on body weight (since protein needs scale with lean mass, not total calorie intake), sets fat as a percentage of the calorie budget, and lets carbohydrates fill whatever calories remain.

This calculator starts by estimating your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, adjusted for your goal, a calorie deficit for cutting, maintenance calories for holding steady, or a surplus for bulking. From there, it applies the bodyweight-first protein allocation that distinguishes IIFYM from simpler tools like the Macro Calculator, which uses fixed macro percentages regardless of body weight. If your priority is total macro flexibility rather than a rigid meal plan, the IIFYM approach is designed specifically for that.

Why Use an IIFYM Calculator?

Fixed-percentage macro splits can misallocate protein, a heavier person following a 30%-protein plan may get more protein than needed, while a lighter person on the same plan may fall short of what's needed to preserve muscle during a deficit. Setting protein directly from body weight avoids this problem and reflects how most flexible dieting coaches actually program macros for clients.

It's especially useful during a cutting phase, when adequate protein is critical to prevent muscle loss alongside fat loss, and during a lean bulk, where hitting a specific protein floor matters more than obsessing over an exact percentage split. Pair it with the TDEE Calculator if you want to understand your maintenance calories in more depth before committing to a cut or bulk phase.

Who Should Use This Calculator?

Flexible dieters who want the freedom to eat a variety of foods while still hitting nutrition targets are the core audience for IIFYM. Bodybuilders and physique athletes in a structured cut or bulk phase benefit from the bodyweight-based protein floor that supports muscle retention or growth. Recreational gym-goers transitioning from a rigid meal plan to a more sustainable, food-flexible approach can use this to set a realistic starting point. Nutrition coaches working with clients on flexible dieting programs can use it as a quick reference for prescribing starting macros. People who've plateaued on generic percentage-based macro plans may find the bodyweight-first protein approach breaks through stalls by ensuring protein intake is adequate. Anyone new to macro tracking should also check the Protein Calculator to understand how protein targets shift across different activity levels and goals.

What Insights Does the IIFYM Calculator Give You?

Daily Calories is the primary result, your total calorie target after adjusting TDEE for your selected goal (cut, maintain, or bulk). Protein (g/day) shows your bodyweight-based protein target, calculated before fat and carbs to ensure it's never shortchanged by a percentage split. Fat (g/day) is calculated as roughly 25–30% of your daily calorie target, supporting hormone and nutrient needs. Carbs (g/day) is whatever calories remain after protein and fat are accounted for, converted to grams, this is usually your largest macro by weight and the one that flexes most with activity level and goal. TDEE, Maintenance Calories is shown alongside your goal-adjusted target so you can see exactly how large your deficit or surplus is.

How to use this IIFYM calculator

  1. Select your Gender, Male or Female.
  2. Enter your Age, Weight in kilograms, and Height in centimetres.
  3. Choose your Activity Level from the dropdown, matching your typical weekly exercise pattern.
  4. Select your Goal, Cut, Maintain, or Bulk.
  5. Review the Daily Calories result and your Protein, Fat, and Carbs targets in grams.
  6. Compare the TDEE figure to your goal-adjusted calorie target to see the size of your deficit or surplus.
Show formula & methodology ↓Show less ↑

Formula & Methodology

BMR (Mifflin-St Jeor equation):

Male: BMR = 10 × Weight(kg) + 6.25 × Height(cm) − 5 × Age + 5

Female: BMR = 10 × Weight(kg) + 6.25 × Height(cm) − 5 × Age − 161

TDEE:

TDEE = BMR × Activity Multiplier (1.2 to 1.9)

Goal-adjusted daily calories:

Cut: TDEE × 0.80 (≈20% deficit) · Maintain: TDEE · Bulk: TDEE × 1.10–1.15 (≈10–15% surplus)

IIFYM macro allocation (bodyweight-first):

Protein(g) = Weight(kg) × 2.2

Fat(g) = (DailyCalories × 0.275) ÷ 9

Carbs(g) = (DailyCalories − Protein×4 − Fat×9) ÷ 4

Worked example: A 70 kg, 30-year-old male, 175 cm tall, moderately active, aiming to Cut: BMR ≈ 1,674 kcal, TDEE ≈ 1,674 × 1.55 ≈ 2,595 kcal, Daily Calories ≈ 2,595 × 0.80 ≈ 2,076 kcal. Protein = 70 × 2.2 = 154g (616 kcal). Fat = (2,076 × 0.275) ÷ 9 ≈ 63g (571 kcal). Remaining calories for carbs = 2,076 − 616 − 571 ≈ 889 kcal → Carbs ≈ 222g.

For a fuller definition, see our glossary entry on IIFYM.

Frequently Asked Questions

What does IIFYM mean?
IIFYM stands for 'If It Fits Your Macros', a flexible dieting approach that focuses on hitting daily targets for protein, fat, and carbohydrates rather than restricting specific foods. As long as a meal fits within your macro targets for the day, the source of those calories (whether from chicken and rice or a slice of pizza) is considered flexible. It grew popular in bodybuilding and fitness communities as an alternative to rigid meal plans.
How is the IIFYM Calculator different from a regular macro calculator?
This calculator uses the IIFYM-specific allocation method: protein is set first based on your body weight (roughly 2.2g per kg), fat is set as a fixed percentage of total calories (around 25–30%), and carbohydrates fill whatever calories remain. Many generic macro calculators instead split all three macros as fixed percentages of total calories, which can under-allocate protein for lighter individuals or over-allocate it for heavier ones. The bodyweight-first method is closer to how flexible dieting coaches actually prescribe macros.
How much protein do I need on IIFYM?
This calculator allocates protein at approximately 2.2 grams per kilogram of body weight, a level well-supported by sports nutrition research for supporting muscle retention and growth during both calorie deficits and surpluses. For a 70 kg person, that works out to roughly 154g of protein per day. This is set before fat and carbs are calculated, since protein needs are driven by body weight rather than total calorie intake.
What percentage of calories should come from fat?
The IIFYM Calculator allocates fat as approximately 25–30% of total daily calories, which is within the range recommended by most dietary guidelines for supporting hormone production and nutrient absorption. Fat is calculated after protein because protein needs are fixed by body weight, and fat is calculated as a percentage of the remaining calorie budget after accounting for the goal-adjusted calorie target.
Are carbs bad for flexible dieting?
No, in the IIFYM approach, carbohydrates simply fill the remaining calories after protein and fat targets are met, and they are treated as an important energy source rather than something to minimize. Athletes and people with high activity levels often benefit from higher carb intake to fuel training and recovery. This calculator's carb allocation will typically be the largest of the three macros for most activity levels and goals.
What is the difference between IIFYM and keto?
IIFYM prioritizes hitting protein, fat, and carb targets with flexibility in food choice, and generally allows moderate-to-high carbohydrate intake depending on the remaining calorie budget. The [Keto Calculator](/keto-calculator/), by contrast, deliberately restricts carbohydrates to 5–10% of calories to induce ketosis, with fat making up the vast majority of intake. They are different macro strategies suited to different goals and preferences.
How do I use the IIFYM Calculator?
Enter your gender, age, weight in kilograms, and height in centimetres. Select your activity level from the dropdown, being honest about your typical weekly exercise. Then choose your goal, Cut, Maintain, or Bulk, and the calculator will show your daily calorie target along with protein, fat, and carb targets in grams.
Can I adjust the protein or fat targets manually?
This calculator uses evidence-based defaults (2.2g/kg protein, ~25–30% fat) that work well for most people pursuing flexible dieting, so manual adjustment isn't built into the tool. If you have specific needs, for example, a physician-recommended higher protein intake, you can use the [Protein Calculator](/protein-calculator/) to explore alternative protein targets by activity level and goal.
What happens to my macros when I switch from Cut to Bulk?
Switching your goal changes your total daily calorie target, a Cut applies a calorie deficit below TDEE while a Bulk applies a surplus, which directly changes how many carbs you're allocated, since carbs fill the remaining calories after protein and fat. Your protein target stays roughly the same (since it is based on body weight, not calorie level), while your fat and carb grams shift up or down with the new calorie total.
Is IIFYM suitable for weight loss?
Yes, IIFYM works well for weight loss because it uses a calorie deficit combined with adequate protein intake, which research consistently shows helps preserve lean muscle mass during fat loss. The flexibility of choosing your own foods within the macro targets also tends to improve long-term diet adherence compared to highly restrictive meal plans, which is often the deciding factor in whether a diet succeeds.
What is TDEE and why does the calculator show it?
TDEE (Total Daily Energy Expenditure) is your estimated maintenance calorie level, the number of calories that would keep your weight stable given your current activity level. The IIFYM Calculator shows your TDEE alongside your goal-adjusted daily calories so you can see exactly how much of a deficit or surplus your chosen goal creates. For a deeper breakdown of TDEE alone, see the [TDEE Calculator](/tdee-calculator/).
Also known as
IIFYMif it fits your macros calculatorflexible dieting calculatormacro calculator bodyweight proteinIIFYM macros