Calculate how many calories you should eat per day to lose, maintain, or gain weight. Uses the Mifflin-St Jeor equation with activity level and macronutrient breakdown.
Last updated: March 2, 2026
Calculate how many calories you should eat per day to lose, maintain, or gain weight. Uses the Mifflin-St Jeor equation with activity level and macronutrient breakdown. This tool runs in-browser for fast results without…
Yes. This calculator is completely free with no signup required. It runs entirely in your browser — no data is stored or shared.
It uses the Mifflin-St Jeor equation to calculate your Basal Metabolic Rate (BMR), then multiplies by an activity factor to estimate Total Daily Energy Expenditure (TDEE). Your goal (lose/maintain/gain) adjusts this by ±500 calories.
A deficit of 500 calories/day below your TDEE typically results in about 0.5 kg (1 lb) of weight loss per week. This calculator shows your target for different goals.
It's the most accurate BMR formula for most people: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (men) or −161 (women). Published in 1990 and validated by the American Dietetic Association.
TDEE Calculator
Calculate Total Daily Energy Expenditure using Mifflin-St Jeor BMR and activity multiplier. Shows calorie targets for weight goals.
Body Fat Calculator (Navy Method)
Calculate body fat percentage using the U.S. Navy method. Shows lean mass, fat mass, and body fat category.
Daily Water Intake Calculator
Calculate daily water needs based on body weight, activity level, and climate. Shows glasses and bottles per day.
Lifespan Calculator
Estimate your life expectancy based on age, sex, lifestyle, diet, exercise, sleep, stress, and health factors. See how long you have left and how to improve it.
Longevity Stack Calculator
Build and budget your biohacking longevity stack. Select from 20+ interventions across supplements, testing, devices, lifestyle, and premium categories with live cost tracking.
Macro Calculator
Calculate protein, carb, and fat grams from your calorie target. Presets for cutting, maintaining, and bulking.
One Rep Max (1RM) Calculator
Estimate your 1RM via Epley, Brzycki, and Lombardi formulas. Percentage chart for training loads.
Pregnancy Due Date Calculator
Calculate your due date from LMP or conception date. Shows trimester timeline, gestational age, and week-by-week milestones.
How many calories should you eat per day?
This calculator uses the Mifflin-St Jeor equation, which research has shown to be the most accurate formula for estimating Basal Metabolic Rate (BMR) for most people. Your BMR is multiplied by an activity factor to estimate Total Daily Energy Expenditure (TDEE).
A deficit of ~500 calories/day results in approximately 0.5 kg (1 lb) of weight loss per week. The calculator enforces a minimum of 1,200 calories/day — going below this is not recommended without medical supervision.
Macronutrient ranges follow general dietary guidelines: 25-35% protein, 40-55% carbs, 20-35% fat. Individual needs may vary — consult a registered dietitian for personalized advice.