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Macro Calculator

Calculate your daily calorie and macro targets

Your Details

The Macro Calculator converts your body statistics into daily nutrition targets: an estimated calorie need plus the grams of protein, carbohydrate, and fat that fit your goal. Enter age, sex, height, weight, activity level, and whether you want to cut, maintain, or bulk, and it returns a starting point you can actually track. It is for people beginning a structured approach to eating who want a defensible number rather than one pulled from a magazine quiz.

How to Use

  1. Enter your details: age, sex, height, and weight. The formula uses each of these directly.
  2. Choose an activity level. The multipliers run from sedentary (1.2) to very active (1.9). Most people overestimate here, so pick the level that matches your typical week rather than your best one.
  3. Select a goal: cut, maintain, or bulk. This sets the calorie adjustment and the macro split.
  4. Read the output: estimated maintenance calories (TDEE), the goal-adjusted calorie target, and grams per macro.
  5. Track for two to three weeks before judging the result. The formula gives a starting point; your own trend data is the real feedback loop.

Worked Examples

Example 1 — cutting. A 34-year-old woman, 168 cm, 72 kg, moderately active. Her estimated maintenance is around 2,100 kcal. Choosing cut subtracts 500, giving a target near 1,600 kcal with protein set high (about 40% of calories) to protect muscle during the deficit. At roughly 0.5 kg per week, the first few kilos come off over about two months, after which the numbers should be recalculated at the new weight.

Example 2 — maintenance. A 40-year-old man, 180 cm, 80 kg, lightly active, estimates around 2,400 kcal for maintenance, with a balanced split near 30% protein, 40% carbohydrate, and 30% fat. Maintenance is the right phase for anyone whose weight is where they want it and who wants to improve body composition or training performance.

Example 3 — bulking. A 24-year-old man, 175 cm, 68 kg, very active, estimates roughly 2,900 kcal for maintenance; bulk adds 500 for about 3,400 kcal, with carbohydrate raised to 45% to fuel training volume and protein at 30%. A surplus this size tends to add around 0.25–0.5 kg per week, which is fast enough to make progress and slow enough to limit fat gain.

How the Numbers Are Calculated

The estimate runs in three stages:

  1. Basal metabolic rate (BMR). The Mifflin-St Jeor equation estimates the calories you would burn at complete rest, using weight, height, age, and sex. It is one of the most accurate general-population formulas available without measuring respiration directly.
  2. Total daily energy expenditure (TDEE). BMR is multiplied by an activity factor — 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extremely active — to account for movement and exercise.
  3. Goal adjustment and macro split. Cutting subtracts about 500 kcal per day, bulking adds about 500, and maintenance leaves TDEE unchanged. The calories are then divided using the goal-specific ratio: higher protein for cutting, higher carbohydrate for bulking. Protein and carbohydrate contribute 4 kcal per gram, fat 9 kcal per gram, which is how the percentages become gram targets.

Why the Estimate Can Miss

Every input in the formula is a proxy. Activity multipliers collapse an entire week of movement into one number, so someone with an active job and no gym sessions can look “sedentary” on paper while burning far more than the estimate suggests. BMR varies between individuals with the same statistics by a meaningful margin, and the equation knows nothing about muscle mass, which burns more energy at rest than fat.

There is also a measurement problem: people underreport intake, sometimes by several hundred calories a day. If the estimate says 2,100 and your weight does not move at what you believe is a 1,600-calorie intake, the discrepancy is more likely in the tracking than in the arithmetic. The formula is a hypothesis; two weeks of consistent weight data is the experiment that tests it.

A Note on Health Decisions

This calculator is a general-purpose estimate, not medical or dietary advice. It does not account for medical conditions, medications, pregnancy, eating disorders, or the specific requirements of competitive sport. Very low calorie targets should not be attempted without supervision, and weight and body-composition goals interact with mental and physical health in ways a formula cannot evaluate. If any of that applies to you, talk to a clinician or registered dietitian who can assess your individual situation.

Common Mistakes

  • Overstating activity level. Choosing “very active” because of one weekly class inflates the target by hundreds of calories and stalls progress.
  • Treating the first number as final. Recalculate after 4–6 weeks or after a meaningful weight change; the input has moved.
  • Chasing the macro split before total calories. Get the calorie target right first, then tune the split for satiety and performance.
  • Judging the result in a week. Water-weight swings obscure real trends; give it two to three weeks of consistent tracking.
  • Cutting too aggressively. A deficit far beyond 500 kcal is hard to sustain nutritionally and tends to cost muscle and sleep.
  • Ignoring how you feel. Persistent fatigue, poor sleep, and declining training performance are signals to revisit the target, not to push harder.

Features

  • BMR estimated with the Mifflin-St Jeor equation
  • Five activity levels with standard multipliers
  • Cut, maintain, and bulk goals with ±500 kcal adjustment
  • Protein, carbohydrate, and fat targets in grams using standard energy factors
  • Recaclulation-friendly inputs for each new phase
  • Fully client-side — body data never leaves the browser

Use Cases

  • Fat loss: Set a moderate, trackable deficit instead of guessing.
  • Muscle gain: Size a surplus that supports training without excess fat gain.
  • Maintenance: Find the intake that keeps weight stable while body composition improves.
  • Meal planning: Convert targets into portion decisions for the day.
  • Recomposition: Start from maintenance and adjust macros toward protein.

Frequently Asked Questions

How accurate is the Mifflin-St Jeor estimate for me personally?

It is a population formula, so it lands close for most adults and can be off by 10% or more for any individual. Factors the equation cannot see include muscle mass, genetic variation in metabolism, medication, thyroid function, and how much you actually move outside formal exercise. Use the result as a starting point, track your weight and energy over two to three weeks, and adjust by 100–200 kcal at a time based on what the scale and your gym performance do.

Is a 500-calorie deficit safe?

A 500 kcal deficit is a common, moderate target that tends to produce about 0.5 kg of fat loss per week, but it is not right for everyone. A deficit that leaves you under roughly 1,200 kcal per day (1,500 for men) is difficult to meet nutritionally without supervision, and aggressive deficits can cost muscle and disrupt sleep. If you are pregnant, underweight, or managing a health condition, speak to a clinician rather than calculating on your own.

Should I recalculate as my weight changes?

Yes. The formula takes body weight as an input, so after losing or gaining several kilograms the original targets are stale. A practical rhythm is to recalculate every 4–6 weeks, or whenever a planned phase changes, and to re-check activity level at the same time — people often underestimate how much their routine has changed.

Do macro ratios matter as much as total calories?

For weight change, total calories dominate. Macros matter for body composition, satiety, and performance: higher protein helps retain muscle in a deficit and tends to be more filling, while higher carbohydrate supports training volume. Hit the calorie target first, then treat the split as the lever you adjust for how you feel and perform.

Why does the tool use 4 calories per gram for protein and carbs, and 9 for fat?

Those are the standard Atwater factors, the accepted average energy yields for the three macronutrients. Protein and carbohydrate provide about 4 kcal per gram and fat about 9, which is why a high-fat food is energy-dense and why the same gram weight of fat contributes more than twice the calories. Alcohol adds a fourth figure, about 7 kcal per gram, which no macro calculator includes.

Is this medical or dietary advice?

No. It is an arithmetic estimate based on published formulas, offered for general information. It does not account for medical conditions, medications, eating disorders, pregnancy, or athletic periodization. For any decision with health consequences, work with a qualified clinician or registered dietitian who can assess your individual situation.

Reviewed by the HandyTools Hub team · Last updated