TDEE Calculator

TDEE calculators are accurate to within approximately plus or minus 10 percent for most people. For someone with a TDEE of 2,500 kcal, the real number could be anywhere from 2,250 to 2,750 kcal. The Mifflin-St Jeor equation predicts within 10 percent of measured BMR for about 70 percent of people. The activity multiplier introduces additional imprecision because it relies on self-assessment. Best practice is to use the calculator as a starting point, then adjust based on two to four weeks of actual weight tracking.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest, just to keep you alive. This includes breathing, circulation, brain function, and cell repair. TDEE (Total Daily Energy Expenditure) includes BMR plus all other energy expenditure: digestion, movement, exercise, and even fidgeting. BMR typically makes up 60 to 70 percent of TDEE. You should eat according to your TDEE, not your BMR. Eating at BMR level would be a very aggressive deficit for most people.

Australia officially uses kilojoules. All food labels must display energy in kJ. One calorie (kcal) equals 4.184 kilojoules. To convert, multiply calories by 4.2 to get kJ, or divide kJ by 4.2 for calories. Most international nutrition research and fitness communities use calories. This calculator displays both so you can use whichever you prefer. For reference, an average Australian adult's TDEE is roughly 8,000 to 10,500 kJ (1,900 to 2,500 kcal).

BMR naturally declines with age, roughly 1 to 2 percent per decade after age 20. The primary driver is loss of lean body mass (sarcopenia). Adults lose approximately 3 to 8 percent of muscle mass per decade after age 30. Lower muscle mass means lower BMR and therefore lower TDEE. Older adults also tend to be less physically active and have lower NEAT. Hormonal changes including declining testosterone, oestrogen, and growth hormone contribute to both muscle loss and metabolic slowdown. This is why strength training becomes increasingly important with age.

Yes, but the difference is often overstated. Muscle tissue burns approximately 13 kcal per kg per day at rest. Fat tissue burns approximately 4.5 kcal per kg per day. So 1 kg of muscle burns about 8.5 kcal more per day than 1 kg of fat. Gaining 5 kg of muscle would increase BMR by roughly 40 to 65 kcal per day. The bigger metabolic benefit of muscle comes from the training itself, post-exercise oxygen consumption, and improved insulin sensitivity, not just resting metabolic rate.

NEAT (Non-Exercise Activity Thermogenesis) is the energy you burn from all movement that is not formal exercise: walking, standing, fidgeting, cooking, cleaning, typing. NEAT can vary by up to 2,000 kcal per day between individuals of similar size. For most people, NEAT accounts for more of their daily calorie burn than deliberate exercise. NEAT subconsciously decreases when you are in a calorie deficit. Tracking daily step count is one of the best proxies for NEAT. Research suggests maintaining 8,000 to 10,000 or more steps per day helps counteract the NEAT decline during weight loss.

Recalculate every 4 to 6 weeks if you are actively losing or gaining weight. For every 1 kg of weight lost, TDEE decreases by roughly 15 to 20 kcal per day from both reduced BMR and reduced movement cost. If weight loss stalls for two or more weeks, recalculate or adjust your activity level downward. After significant weight loss of 10 or more kilograms, adaptive thermogenesis means your actual TDEE may be lower than any calculator predicts. For weight maintenance with no major changes, recalculating every 6 to 12 months is sufficient.

Yes. Men generally have a higher TDEE than women, primarily because men have more lean body mass on average. The Mifflin-St Jeor equation has separate formulas for each sex. Even after accounting for body size and composition, small hormonal differences influence metabolic rate. Women's TDEE fluctuates with the menstrual cycle and can be 100 to 300 kcal higher in the luteal phase. During pregnancy, energy needs increase by approximately 340 kcal per day in the second trimester and 450 kcal in the third trimester.

Fitness trackers have variable accuracy. A Stanford study in 2017 found that even the most accurate wrist-worn devices had a median error of about 27 percent for energy expenditure, while heart rate accuracy was much better at about 5 percent error. They tend to overestimate calorie burn, especially during weight training and high-intensity intervals. Use your tracker to compare relative activity between days rather than treating the calorie number as exact. Do not eat back all exercise calories your tracker reports, as this commonly leads to overeating.

There is no universal minimum, but common clinical guidelines suggest women generally not go below approximately 1,200 kcal per day (5,000 kJ) and men not below approximately 1,500 kcal per day (6,300 kJ) without medical supervision. Below these thresholds it becomes difficult to meet micronutrient needs from food alone. Very low calorie diets under 800 kcal per day should only be followed under medical supervision. The NHMRC does not set a specific minimum calorie intake but emphasises meeting all nutrient reference values. Anyone with a history of eating disorders should approach calorie tracking with caution.