BMR Calculator

What the boxes mean

Sex at birth, age, weight and height feed the Mifflin-St Jeor equation. Activity level is the multiplier that turns a resting figure into a whole-day one. The units toggle swaps kg and cm for pounds and total inches.

Activity is the box that decides whether this page is useful, so the options are written the way an Indian week actually runs:

• Sedentary: office job, cab or metro to work, no exercise. This is most of urban India, whatever the step counter on the phone says.
• Light: a walk in the society park or a gym visit one to three days a week.
• Moderate: real exercise three to five days a week. Badminton, running, a proper gym session.
• Active: hard training six or seven days.
• Very active: a physical job all day (a delivery rider, farm labour, a site worker, a nurse on the ward) or training twice a day.

Mifflin-St Jeor, worked for a 70 kg man

male:   BMR = 10 × kg + 6.25 × cm − 5 × age + 5
female: BMR = 10 × kg + 6.25 × cm − 5 × age − 161

The default is a 34-year-old man, 70 kg, 165 cm, exercising three to five days a week.

BMR  = 10 × 70 + 6.25 × 165 − 5 × 34 + 5
     = 700 + 1031.25 − 170 + 5
     = 1566.25 kcal

TDEE = 1566.25 × 1.55 = 2427.69 kcal

BMR (at rest)	1,566 kcal
Daily calories burned	2,428 kcal
To lose about half a kg a week	1,928 kcal
To gain about half a kg a week	2,928 kcal

The multipliers are the standard set: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active. The same man with a desk job and no exercise drops to 1,880 kcal a day. As a delivery rider on the road all day he goes up to 2,976.

Notice that 1,566 of the 2,428 is spent lying still. Roughly two thirds of what you burn is your liver, brain, kidneys and heart doing their job. Exercise is the smaller slice, which is why “I will burn it off at the gym” so rarely balances the books.

1,566 kcal on a plate

A figure in kcal means nothing until it is next to food you actually eat. These are approximate, because a roti in Ludhiana is not a roti in Madurai:

Item	Roughly
Phulka, no ghee	70 to 80 kcal
Roti with ghee	100 kcal
Cup of cooked rice (about 150 g)	200 kcal
Katori of dal	150 kcal
Samosa	250 kcal
Cutting chai with sugar	60 to 70 kcal
Plate of poha	250 to 300 kcal

So the resting burn is about twenty phulkas, or eight cups of rice, or six samosas, before the day has started. The full 2,428 kcal is a normal thali at lunch and dinner, breakfast, two chais and one evening snack. That is how a moderately active man stays at 70 kg without ever thinking about it, and it is also why one extra samosa every day, on paper, is close to 12 kg a year at 7,700 kcal per kilogram. In practice the body adapts and it is less, but the direction is right.

How this squares with the ICMR-NIN numbers

The Indian reference for how much people should eat is the ICMR-NIN Nutrient Requirements for Indians, last revised in 2020. It works from a reference man of 65 kg and a reference woman of 55 kg and quotes energy by work intensity: about 2,110 kcal a day for a sedentary man, 2,710 for moderate work and 3,470 for heavy work, and for women about 1,660, 2,130 and 2,720. Those are the 2020 figures as I have them; NIN publishes the full table and that is the place to check the exact line.

The calculator will not match them, and should not. The RDA is a population average for a reference body. The equation is an estimate for yours. A 70 kg man with a desk job gets 1,880 kcal here against NIN’s 2,110 for a sedentary 65 kg man, and the gap is mostly the multiplier: NIN’s sedentary factor is about 1.53, the calculator’s is 1.2, because the NIN definition still assumes the walking, standing and housework that an Indian day used to include and that a cab commute and a Swiggy account have removed.

Which of the two is right for you is an empirical question. Eat to one of them for three weeks, weigh yourself every morning, and the scale will tell you.

Choosing the activity level honestly

This is the input everyone gets wrong, and always in the same direction.

A 10,000-step day on the phone is not moderate; it is the top of light. Feeling exhausted after a nine-hour shift at a desk is not activity. A desk job plus gym three times a week is moderate, not active. Very active is a farm worker in harvest season or a rider doing forty deliveries, not an enthusiastic gym habit.

Picking one level too high adds 400 or 500 kcal to the maintenance figure, and then the “deficit” built on it is no deficit at all. When in doubt, pick lower.

One thing the equation cannot see: at the same weight an Indian body usually carries less muscle than the American sample Mifflin and St Jeor worked with in 1990, and muscle is what burns at rest. So 1,566 is, if anything, slightly generous for a thin-fat build. Nothing to do about that except treat the number as a starting point.

If what you want is a target to eat to, rather than a burn figure, go to the calorie calculator, which starts from this same equation and subtracts for the rate of loss you choose. If you are not sure the weight is fat in the first place, the body fat calculator will tell you with a tape measure, and the BMI calculator shows where 70 kg at 165 cm lands on the Indian cut-offs.