Monster Calorie Calculator
Your maintenance calories, targets for losing or gaining at the pace you pick, and the macro split to go with them — more goal rates and diet styles than the standard calculators offer.
How it works
Your resting burn (BMR) comes from the Mifflin-St Jeor equation — men: 10×kg + 6.25×cm − 5×age + 5; women: the same minus 161. Multiplying by your activity factor gives TDEE, the calories that hold your weight steady. A pound of body fat stores roughly 3,500 kcal, so a steady 500 kcal/day deficit or surplus moves weight by about a pound a week (the goal menu uses that math, with safety floors of 1,500 kcal for men and 1,200 for women). Macros convert at 4 kcal per gram of protein or carbs and 9 per gram of fat.
Formula & worked example
Formula: BMR uses Mifflin-St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women. TDEE = BMR × an activity factor from 1.2 (sedentary) to 1.9 (athlete). Your goal then adds or subtracts calories — never below a floor of 1,500 (men) or 1,200 (women) — and macros split the target using 4 kcal per gram of protein or carbs and 9 kcal per gram of fat.
Worked example: A 30-year-old man of 80 kg and 180 cm: BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal. At moderate activity (× 1.55) he maintains on 2,759 kcal, and the Balanced 30/40/30 split works out to 207 g protein, 276 g carbs and 92 g fat.
When to use this
- You are setting a daily calorie target for losing, maintaining or gaining — with a number, not a guess.
- You want macro grams attached to that target in the split you actually eat.
- Your weight has plateaued and you want to re-derive the target from current stats.
- You are sanity-checking an app's suggested target against the standard equations.
How to use it, step by step
- Enter sex, age, height and current weight.
- Pick the activity level that matches your week, not your best week.
- Choose the goal — the target adjusts by the standard ±250/500 kcal steps.
- Pick a macro style and read grams, not just percentages.
- Re-run monthly as weight changes; a lighter body needs less.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Weight / height | Current stats the equations run on | Weigh weekly; height in cm or ft/in |
| Activity level | Multiplier over resting burn | Sedentary 1.2 to athlete 1.9 |
| Goal | Deficit or surplus step | ±500 kcal ≈ 0.5 kg/week theoretical |
| Macro style | Protein/carb/fat percentage split | Balanced 30/40/30 default |
Another worked example
A 35-year-old woman, 70 kg and 165 cm, sedentary job: BMR is 1,395 kcal and maintenance (TDEE) about 1,674 kcal a day. A −500 goal sets her target near 1,174 kcal — aggressive enough that many people do better on the −250 step (about 1,424), trading speed for a plan they can still be on in month three.
Frequently asked questions
How many calories do I need to maintain my weight?
That is your TDEE: BMR multiplied by activity (1.2 sedentary up to 1.9 athlete). For a moderately active 30-year-old man at 80 kg and 180 cm it is about 2,760 kcal a day — the calculator shows yours with every activity level for comparison.
How big a deficit is safe for weight loss?
A 250–500 kcal daily deficit (roughly 0.25–0.5 kg a week) is the range most guidelines consider sustainable. The fast −1,000 option is aggressive, and this calculator floors targets at 1,500 kcal (men) and 1,200 kcal (women) — eating below that belongs under medical supervision.
Why do macros matter if calories are equal?
Calories drive weight change, but the split drives how you feel getting there: protein protects muscle and satiety, carbs fuel training, fats cover hormones and absorption. The four styles let you match the split to how you actually eat.
Is Mifflin-St Jeor the best formula?
For most adults it is the most accurate of the common equations in validation studies, which is why dietitians default to it. If you know your body-fat percentage, the BMR Calculator's Katch-McArdle option can be closer for very lean or very heavy builds.
⚡ Want BMR three different ways?
The BMR Calculator compares Mifflin-St Jeor, Harris-Benedict and Katch-McArdle side by side.
Why do two calculators give me different targets?
They may use different BMR equations (Mifflin–St Jeor here), different activity multipliers, or different deficit steps. Differences of ±100 kcal are normal; treat the first two weeks of real results as the calibration and adjust by ~100 kcal at a time.
Should I eat back exercise calories?
Usually not on top of an activity multiplier — the multiplier already assumes your typical training. Double-counting exercise is the most common reason a 'deficit' does not lose weight.