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About this tool
Calculate your Total Daily Energy Expenditure (TDEE) and macronutrient splits based on your goals.
The Calorie & Macro Calculator works out your daily calorie target and the gram split of protein, carbs and fat behind it, using the Mifflin-St Jeor equation for BMR (10 × kg + 6.25 × cm − 5 × age, then +5 for men or −161 for women), an activity multiplier from 1.2 to 1.9 for TDEE, and a goal adjustment of ±250 or ±500 kcal. It then divides the target into a 30% protein / 40% carbohydrate / 30% fat split and converts those calories to grams at 4, 4 and 9 kcal per gram. Everything is shown — BMR, TDEE and target — so you can see which step produced the number, not just the final figure.
Open Calorie & Macro Calculator on AltFTool — it loads instantly in your browser.
Fill in Age, Gender, Height (cm) and Weight (kg) in the left card. Age, Height and Weight are all required — leave one blank and nothing is calculated.
Pick an Activity Level, from 'Sedentary (Little or no exercise)' up to 'Very Active (Physical job or 2x training)', then set Your Goal anywhere between 'Aggressive Weight Loss (-500 kcal)' and 'Aggressive Weight Gain (+500 kcal)'.
Press 'Calculate Macros'. The Daily Target card shows your kcal figure with your BMR and TDEE underneath, and the Protein, Carbs and Fats tiles split it 30% / 40% / 30% beside a Macro Distribution chart.
You can see that a −500 goal is a deficit against your maintenance number rather than an arbitrary figure, which makes it easy to adjust later.
The 30/40/30 split is converted at 4 kcal per gram of protein and carbohydrate and 9 per gram of fat, so you get numbers you can actually log.
The BMR step uses the equation most dietetic practice guidelines favour for non-athletes, and the tool tells you the BMR it derived so you can cross-check it.
BMR is what you would burn at complete rest; TDEE is BMR multiplied by an activity factor to cover movement, exercise and digestion. This tool uses 1.2 for sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 active and 1.9 very active — so an office worker and a construction worker with identical bodies can differ by more than 1,000 kcal a day.
The tool offers −250 and −500 kcal per day. A 500 kcal daily deficit corresponds to roughly 0.45 kg of body weight per week using the traditional 7,700 kcal-per-kg approximation, while −250 is about half that and is generally easier to sustain. Very low targets are a matter for a dietitian or doctor rather than a calculator.
It is a balanced general-purpose split that sits inside the widely used acceptable macronutrient distribution ranges (roughly 10-35% protein, 45-65% carbohydrate, 20-35% fat). At a 2,000 kcal target it works out to 150 g protein, 200 g carbohydrate and 67 g fat. Athletes, low-carb eaters and people with medical conditions will want a different ratio.
It predicts measured resting energy expenditure within 10% for roughly 70-80% of people, and it tends to be less accurate at the extremes of body composition because it uses total weight rather than lean mass. Treat the output as a starting point, then adjust based on two to four weeks of real weight data. This is general information, not medical or dietary advice.
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