BMR and TDEE, explained simply
Your BMR (basal metabolic rate) is the energy your body uses just to keep you alive at rest — breathing, pumping blood, staying warm. Your TDEE (total daily energy expenditure) is that plus everything you do: moving, working, exercising. TDEE is the number that matters most, because it is roughly the calories you burn on a normal day. This calculator uses the well-regarded Mifflin-St Jeor equation for BMR, then scales it by your activity level.
Calories and your goal
To stay the same weight, you eat around your TDEE. To lose weight gently, you eat a little less; to gain, a little more. The "gentle" options here use a modest change of a few hundred calories — the kind of pace that tends to be sustainable. Crash diets with huge cuts usually backfire, and they are not something this tool will suggest.
What about macros?
The split this calculator shows is 30% protein, 40% carbohydrate and 30% fat. At the worked example's maintenance figure of 2,701 kcal that means 203 g of protein, 270 g of carbohydrate and 90 g of fat — protein for muscle, carbohydrate for energy, fat for hormones and general health. It is one workable split among many: athletes often want more protein, and a different split still has to add up to the same daily total. Treat the grams as a starting point to adjust from, not a prescription.
Please read this
These figures are general estimates, not a personalised diet plan or medical advice. Everybody's needs differ, and very low intakes can be harmful. Before making big changes to how you eat — especially if you are very active, have a health condition, are pregnant, or have any history of disordered eating — please talk to a doctor or a registered dietitian.
Worked example: maintenance, loss and gain
Take a man aged 35, weighing 80 kg, 178 cm tall, moderately active (activity factor 1.55). The Mifflin-St Jeor equation gives his BMR as 10 × 80 + 6.25 × 178 − 5 × 35 + 5 = 800 + 1,112.5 − 175 + 5 = 1,742.5 kcal. His TDEE is 1,742.5 × 1.55 = 2,700.88, shown as 2,701 kcal. Maintenance means eating around that figure. Gentle loss subtracts 500: 2,700.88 − 500 = 2,200.88, shown as 2,201 kcal. Gentle gain adds 300: 2,700.88 + 300 = 3,000.88, shown as 3,001 kcal. The macro split at maintenance, using the calculator's 30% protein, 40% carbohydrate and 30% fat split, is protein 2,701 × 0.30 ÷ 4 = 203 g, carbohydrate 2,701 × 0.40 ÷ 4 = 270 g, and fat 2,701 × 0.30 ÷ 9 = 90 g. The division by 4 and 9 reflects the energy in each gram: roughly 4 kcal per gram of protein or carbohydrate, 9 kcal per gram of fat.
| Goal | Daily calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| Maintain | 2,701 kcal | 203 g | 270 g | 90 g |
| Gentle loss | 2,201 kcal | — | — | — |
| Gentle gain | 3,001 kcal | — | — | — |
A second example, with the floor in play
Take a woman aged 28, weighing 62 kg, 165 cm tall, lightly active (factor 1.375). Her BMR is 10 × 62 + 6.25 × 165 − 5 × 28 − 161 = 620 + 1,031.25 − 140 − 161 = 1,350.25 kcal. Her TDEE is 1,350.25 × 1.375 = 1,856.59, shown as 1,857 kcal. Gentle loss gives 1,856.59 − 500 = 1,356.59, shown as 1,357 kcal, with macros of protein 1,357 × 0.30 ÷ 4 = 102 g, carbohydrate 1,357 × 0.40 ÷ 4 = 136 g, and fat 1,357 × 0.30 ÷ 9 = 45 g. Notice what did not happen: the loss figure stayed above the calculator's floor of 1,200 kcal for women, so no clamping kicked in. The floor exists for the opposite case — a smaller, less active person whose TDEE minus 500 would fall below 1,200 (women) or 1,500 (men). In that case the calculator stops at the floor rather than suggesting an intake the page itself warns can be harmful. A floor is not a target: eating at the floor is still very low, and the page advises talking to a doctor or registered dietitian before making big changes, especially with a health condition, pregnancy, or any history of disordered eating.
Activity factors, and why BMR is not the same as BMI
The five activity levels on this page carry fixed multipliers: sedentary 1.2, lightly active 1.375, moderately active 1.55, very active 1.725, and extremely active 1.9. Moving one level changes everything downstream: the same man above at the sedentary factor would have a TDEE of 1,742.5 × 1.2 = 2,091 kcal instead of 2,701, a difference of 610 kcal a day from activity alone. That is why honest activity selection matters more than decimal-point precision on height or weight. One confusion to clear up: BMR is not BMI. BMI, covered by the BMI Calculator, relates weight to height as a screening number; BMR is the energy cost of staying alive at rest. They share inputs but answer different questions, and neither on its own is a diet plan — which is why this page pairs its calorie figure with a macro split, a goal adjustment, and the warning to adjust based on how your body actually responds over a few weeks.
Frequently asked questions
How many calories should I eat to lose weight?
On this page's worked example, gentle loss means your TDEE minus 500 kcal: the 35-year-old man at 2,701 kcal maintenance would aim for 2,201 kcal, and gentle gain means TDEE plus 300, or 3,001 kcal for him. The calculator never drops the loss figure below 1,200 kcal for women or 1,500 kcal for men — it stops at that floor instead. Your own figure depends on your age, weight, height and activity level, so run your numbers through the calculator above rather than borrowing his.
Are these numbers exact?
No — they are good estimates. Real needs vary with genetics, muscle mass and more, so adjust based on how your body actually responds over a few weeks.
Why does the loss figure have a floor?
Because very low intakes can be harmful, and the calculator refuses to suggest them. Gentle loss subtracts 500 kcal from TDEE, but if that result falls below 1,200 kcal for women or 1,500 kcal for men, the calculator stops at the floor instead. The floor is a safety limit, not a recommendation: eating at the floor is still very low, and the page advises professional guidance before making big dietary changes, especially with a health condition, pregnancy, or any history of disordered eating.
Should I eat below my BMR?
Not as a plan. BMR is what your body uses just to stay alive at rest — breathing, pumping blood, staying warm — so an intake below BMR means the deficit is being taken from basic functioning, not just from activity. The calculator's loss figures stay above BMR for most people precisely because the 500 kcal reduction comes off TDEE, which includes activity. If your loss figure ever approaches your BMR, treat that as a signal to get professional advice rather than to push further.