TDEE Calculator - Daily Calorie & Macro Targets

What Is TDEE and Why It Matters

Your Total Daily Energy Expenditure is the total number of calories your body burns in a full 24-hour period. It encompasses every energy-consuming process — from the involuntary work of keeping your heart beating and lungs breathing to the calories torched during a sprint workout and even the energy spent digesting your lunch. TDEE is the single most important number in any nutrition plan because it defines the line between gaining weight and losing it. Eat consistently below your TDEE and you will lose body fat over time. Eat above it and you will gain weight. Eat at it and your weight will stay roughly the same. Understanding your personal TDEE removes the guesswork of generic “2,000 calorie” guidelines and replaces it with a number rooted in your own physiology, size, and lifestyle.

The Mifflin–St Jeor Equation Explained

This calculator uses the Mifflin–St Jeor equation, published in 1990 and widely regarded as the most accurate predictive formula for resting metabolic rate in healthy adults. It replaced the older Harris–Benedict equation (1919), which tends to overestimate calorie needs by 5–15% in modern populations due to changes in average body composition. The Mifflin–St Jeor formula takes your weight in kilograms, height in centimetres, and age in years, then applies a gender-specific constant (+5 for males, −161 for females) to produce your Basal Metabolic Rate (BMR). Your BMR is then multiplied by an activity factor — ranging from 1.2 for sedentary desk workers up to 1.9 for elite athletes — to arrive at your TDEE.

Why Activity Level Is the Biggest Error Source

The most common mistake people make when calculating their TDEE is overestimating their activity level. The activity multiplier represents your entire day, not just your workout. Someone who exercises for an hour but spends the remaining 23 hours sitting at a desk, commuting, and watching television is still largely sedentary. A genuinely “Very Active” person is on their feet all day — think construction workers, mail carriers, or full-time athletes in heavy training. If you are unsure, start one level lower than you think you are and adjust based on results after two to four weeks. A small underestimate is far less costly than a large overestimate, which can completely erase a planned caloric deficit.

Metabolic Adaptation and Why Calories Need Adjusting

Your metabolism is not fixed. As you lose weight, your body becomes smaller and requires fewer calories to maintain itself — a process called metabolic adaptation. For every 10 pounds lost, your TDEE can drop by roughly 50–100 calories per day. This is why weight loss often stalls after several weeks even with consistent adherence: the deficit that worked at the start is no longer a deficit at your new, lighter body weight. The solution is to recalculate your TDEE every four to six weeks and update your calorie targets. Crash dieting accelerates adaptive thermogenesis even further, which is one reason this calculator caps its most aggressive rate at 1.5 lb per week and encourages the moderate 1 lb per week option for most people.

The Dangers of Eating Too Little

Aggressive caloric restriction — eating well below your BMR — does not accelerate fat loss in a sustainable way. Very low calorie diets trigger a cascade of negative effects: increased cortisol production, significant lean muscle loss, hormonal disruption (including suppressed thyroid output and, in women, loss of menstrual regularity), impaired immune function, and intense cravings that often lead to binge episodes. Research shows that deficits greater than 25% of TDEE dramatically increase the ratio of muscle lost relative to fat lost. A moderate deficit of 500–750 calories per day (roughly 1–1.5 lb per week) preserves muscle, keeps energy levels stable, and is far more sustainable over months of dieting. If your calculated target falls below 1,200 cal for women or 1,500 cal for men, it is worth consulting a dietitian rather than simply cutting harder.

Protein Requirements for Active Individuals

The government-set Recommended Dietary Allowance of 0.36 g of protein per pound of body weight is a minimum to prevent deficiency, not an optimal target for anyone trying to build muscle or retain it during a cut. Sports nutrition research consistently supports intakes of 0.7–1.0 g per pound of body weight for active individuals. During a caloric deficit, pushing protein even higher — up to 1.2 g/lb — helps preserve lean mass while your body draws on fat stores for energy. This calculator targets 0.8–1.0 g per pound of your current body weight, adjusted slightly by goal. If the gram number seems high, try spacing your protein across four or five meals and including a source at every sitting: eggs, poultry, fish, dairy, legumes, or a quality protein powder.

Calorie Cycling: A Smarter Way to Diet

Calorie cycling (sometimes called zig-zag dieting) alternates between higher-calorie and lower-calorie days while keeping your weekly average on target. On training days you eat more — typically 10–20% above your daily target — to fuel performance and recovery. On rest days you eat less, creating a slightly deeper deficit when your body does not need the extra fuel. The weekly total stays the same as eating a flat number every day, but the variation offers two key benefits: it can reduce the metabolic slowdown associated with prolonged dieting, and it makes adherence easier because you always have a higher-calorie day on the horizon. The calorie cycling plan available to subscribers in this calculator automatically distributes your weekly calories into a research-backed pattern across all seven days of the week.

Looking for related tools? Try our Macro Calculator to break your calories into protein, carbs, and fat targets, or explore all Health & Fitness tools.