Longevity Tools
Find exactly how many calories your body needs each day — at rest and with activity. Then split those calories into optimal protein, carb, and fat targets that support your health and longevity goals.
Your Metabolic Numbers
Daily Calorie Targets by Goal
Daily Macro Targets
Your Basal Metabolic Rate (BMR) is the number of calories your body burns simply to stay alive — to keep your heart beating, your lungs breathing, your brain functioning, and your cells repairing. It is the energy cost of existence itself, measured at complete rest. Even if you spent an entire day in bed without moving, your body would still consume your BMR in calories just to maintain its basic biological machinery.
Your Total Daily Energy Expenditure (TDEE) takes that baseline and layers on the calories you burn through movement — walking, working out, fidgeting, climbing stairs, and every other form of physical activity throughout your day. TDEE is the number that actually governs your weight: eat at your TDEE and your weight holds steady; eat below it and you lose weight; eat above it and you gain. It is the single most important metabolic number for anyone trying to manage their body composition intelligently.
Understanding both numbers removes the guesswork from nutrition entirely. Instead of following generic advice or unsustainable crash diets, you have a personalized, science-based calorie target built specifically for your body, your age, your height, your weight, and your lifestyle.
This calculator uses the Mifflin-St Jeor Equation — the most widely validated BMR formula in modern nutrition science, recommended by the Academy of Nutrition and Dietetics over older methods like the Harris-Benedict equation. The formulas are:
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Your BMR is then multiplied by an activity factor — ranging from 1.2 (sedentary) to 1.9 (extremely active) — to produce your TDEE. The macro split uses a standard balanced ratio: 30% of calories from protein (4 kcal/g), 40% from carbohydrates (4 kcal/g), and 30% from fat (9 kcal/g). Protein targets are also cross-checked against the evidence-based recommendation of 1.6–2.2g per kg of body weight for active individuals.
The connection between nutrition and lifespan is one of the most robustly studied areas of longevity science. Chronic overconsumption of calories is one of the leading drivers of obesity, type 2 diabetes, cardiovascular disease, and certain cancers — collectively responsible for the majority of preventable deaths worldwide. Conversely, maintaining a healthy body weight through accurate calorie awareness is one of the most powerful things you can do to extend both your lifespan and your healthspan — the years you remain fully functional and energetic.
Protein intake is particularly critical as we age. After age 30, adults naturally lose 3–8% of muscle mass per decade in a process called sarcopenia. Adequate protein intake — combined with resistance exercise — is the primary nutritional defense against this decline. Preserving muscle mass into older age is strongly associated with independence, metabolic health, reduced fall risk, and longevity.
Knowing your numbers is the first step. The days you fuel your body with intention are the days you invest in a longer, more energetic future. Every meal is a choice — and now you have the data to make it a good one.
Enter your age, sex, weight, height, and activity level as accurately as possible. For activity level, most people overestimate — if you work a desk job and exercise three times per week, "lightly active" is almost certainly the right choice. Overestimating activity is the most common reason people plateau on a diet they believe should be working.
Once you have your TDEE, set your calorie target based on your goal: subtract 300–500 calories for steady fat loss (roughly 0.5–1 lb per week), eat at maintenance to hold your current weight, or add 200–300 calories above TDEE to support lean muscle growth without excessive fat gain. Recalculate every 4–6 weeks as your weight changes, since your BMR shifts with your body composition.
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