Calculate your personalised calories, macros, hydration, and 12-week weight projection in under 60 seconds — powered by peer-reviewed science, completely free.
Not a rough estimate — a science-grade breakdown built for your exact body and goals.
Mifflin-St Jeor formula with FAO/WHO/UNU activity multipliers gives the most accurate calorie target for your lifestyle.
Protein, carbs, and fat targets calculated using ISSN and ACSM guidelines — scaled precisely to your body weight and goal.
EFSA-backed daily water targets adjusted for your body weight and activity level — not a one-size-fits-all 2L.
See your body weight trajectory plotted week by week based on your calorie deficit or surplus rate — realistic and science-backed.
Practical Indian food sources and sample meal plans from ₹100 to ₹500 per day, making nutrition affordable for everyone.
ICMR-NIN 2020 recommended daily allowances for Vitamin D, Iron, Calcium, Zinc, B12, Potassium and more.
No guesswork. No fitness trackers. Just your body stats and your goal.
Age, weight, height, and biological sex — used only to calculate your Basal Metabolic Rate with the gold-standard Mifflin-St Jeor equation.
Select your typical weekly activity level, then choose your goal — from aggressive fat loss to maximum muscle growth.
Instantly receive your calorie target, macro split, hydration goal, food sources, budget planner, and 12-week weight projection.
Whether you need a calorie deficit calculator to kickstart weight loss or a precise lean bulk calculator for muscle gain, NutritionOS provides an uncompromising, science-first approach. We aggregate evidence-based formulas—such as the Mifflin-St Jeor equation—into a single maintenance calorie calculator. Unlike a standard calorie calculator, our system factors in your exact physical activity level to accurately determine your TDEE (Total Daily Energy Expenditure).
If you are focused on optimizing body composition, our advanced macro calculator acts as your personal protein intake calculator and cutting calculator. We use recommendations from the ISSN (International Society of Sports Nutrition) to ensure your diet supports high performance, whether your goal is aggressive fat loss, body recomposition, or using a bulking calculator or weight gain calculator. Ideal for users worldwide, including those searching for an accurate maintenance calorie calculator india with localized, budget-friendly meal structures.
Evidence-based answers to common nutrition questions.
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a 24-hour period. It includes your Basal Metabolic Rate (BMR) plus the calories you burn through physical activity and digestion.
BMR (Basal Metabolic Rate) is the number of calories your body requires to perform basic life-sustaining functions, such as breathing, circulation, and cell production, while at complete rest.
To lose weight, you should eat fewer calories than your TDEE (caloric deficit). To gain muscle, you should eat more than your TDEE (caloric surplus). To maintain weight, eat exactly your TDEE. A standard deficit or surplus is usually 10-20% of your TDEE.
Weight loss requires a sustained caloric deficit. Calculate your TDEE, then consume 10-20% fewer calories than you burn each day. Combine this with a high-protein diet and resistance training to preserve muscle mass.
Muscle gain requires a slight caloric surplus, sufficient protein intake (1.6-2.2g per kg of body weight), and progressive overload through resistance training. Using a bulking calculator helps determine the right surplus to minimize fat gain.
For muscle growth and preservation, aim for 1.6 to 2.2 grams of protein per kilogram of body weight (0.7-1g per pound). Sedentary individuals need less (around 0.8g/kg), but higher protein diets are beneficial for weight management.
Body recomposition is the process of losing body fat and building muscle mass simultaneously. It is best achieved by eating at a slight caloric deficit or maintenance, consuming a high-protein diet, and engaging in intense resistance training.
NutritionOS uses the Mifflin-St Jeor equation, which is considered the gold standard and most accurate formula for estimating BMR in modern populations. However, all calculators provide estimates; you should monitor your progress and adjust intake accordingly.
We use the Mifflin-St Jeor equation for Basal Metabolic Rate (BMR) and evidence-based Physical Activity Level (PAL) multipliers to determine Total Daily Energy Expenditure (TDEE). Macronutrient ratios are based on peer-reviewed sports nutrition guidelines.
Yes, NutritionOS is 100% free forever. There are no signups, paywalls, or hidden fees. We believe access to scientific nutrition planning should be free for everyone.
Every formula, multiplier and recommendation in NutritionOS is sourced from published nutrition science. We don't make up numbers.
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Start My Plan →NutritionOS provides educational estimates based on established nutrition and exercise science. Calculations are derived from validated research, including the Mifflin-St Jeor equation and evidence-based nutrition guidelines. Individual requirements vary based on genetics, health status, activity levels, and other factors. Always consult a qualified healthcare professional before making significant dietary changes.