How Many Calories Do I Burn a Day?

The average adult burns about 2,437 calories a day. A woman of median US height and weight burns 2,014 to 2,543 kcal and a man 2,581 to 3,345 kcal, depending on activity. Both figures come from the National Academies’ 2023 energy report, which measured burn in 5,456 adults and published equations to estimate yours.

How many calories does the average person burn a day?

About 2,437 kcal, with a standard deviation of 592 kcal. That is mean total energy expenditure, the formal name for everything you burn in a day, across 5,456 adults with a mean age of 52.6. It was measured with doubly labeled water, a lab method that follows your burn through ordinary life instead of a short test.

An average hides the groups, so I pulled the report’s own tables. They give the burn of a weight-stable adult at the median US height and weight, split by activity level. Activity level is your total burn divided by your resting burn. The report’s tables call below 1.53 inactive, 1.53 to 1.69 low active, 1.69 to 1.85 active and 1.85 to 2.5 very active.

Median US adult	Inactive	Low active	Active	Very active
Women, all adults (161.2 cm, 73.2 kg)	2,014	2,178	2,317	2,543
Women, 19–30 (162.7 cm, 69.3 kg)	2,152	2,316	2,454	2,683
Women, over 70 (156.8 cm, 69.7 kg)	1,737	1,896	2,035	2,249
Men, all adults (175.4 cm, 87.2 kg)	2,581	2,799	2,994	3,345
Men, 19–30 (176.1 cm, 81.4 kg)	2,775	2,988	3,177	3,516
Men, over 70 (172.2 cm, 83.3 kg)	2,181	2,389	2,586	2,896

Values in kcal a day. Find your row, then pick the level that matches a normal week.

Two groups of women weigh almost the same, 69.3 kg and 69.7 kg, yet the older group burns 415 kcal less at the inactive level, which is 19% lower. The tables use ages 25 and 80 for those groups. In the inactive equation that is 55 years × 7.01 = 386 kcal for age and 5.9 cm × 5.72 = 34 kcal for height, with a few kcal back from the extra 0.4 kg. That sum is mine, but it reproduces the table.

The NHS gives a looser guide of 2,000 kcal a day for an average woman and 2,500 for an average man. It says age, weight, height and exercise change that. The table above is the same idea in more detail. Write down the low-active number from your row today as a first guess, then test it against the scale for a few weeks.

What makes up the calories I burn in a day?

Three things: resting metabolism, digesting food and moving. Resting energy expenditure, the energy your body uses just to keep running, typically accounts for 60 to 70 percent of the total. The thermic effect of food, the cost of digesting and absorbing a meal, is about 10 percent. Physical activity is the variable part, and the report puts it at 15 to 50 percent.

I built the split for the average adult. The report measured resting burn in 2,364 of its adults, at a mean of 1,487 kcal. It takes activity as whatever is left after resting burn and food. Those are different subsets of people, so the shares won’t add up the way one person’s day would.

Part of the day’s burn	kcal a day	Share
Resting metabolism	1,487	61%
Digesting food (10% of the total)	244	10%
Everything you do while awake	706	29%
Total	2,437	100%

Fat-free mass, which is muscle, organs, bone and water, explains 60 to 80 percent of the differences between people in resting burn. The same chapter puts fat tissue at about 5 kcal per kg and fat-free mass at about 20 kcal per kg. Ten kilograms of each is 50 kcal against 200 kcal a day, by my arithmetic. Those are tissue rates, so they say nothing about how fast anyone gains muscle.

To see how far activity can move it, I used the 2024 Compendium of Physical Activities, which rates a walk at 3 mph at 3.8 METs. One MET is about 1 kcal per kg per hour. A 70 kg adult therefore uses 3.8 × 70 = 266 kcal an hour, of which 2.8 × 70 = 196 kcal is on top of resting. Half an hour adds 98 kcal. Against the 2,269 kcal day of the woman below, that is 4%.

The only slice you can move on a Tuesday is the last row of that table, and it moves slowly. Each activity has its own number under calories burned, the odd ones included, like how many calories sex burns.

How much does my job change the activity part?

Work gets a rating as well. The Compendium’s occupation table lists four rows that cover most days:

• Sitting at a computer: 1.3 METs
• Standing light tasks, such as store clerk or bartending work: 1.8
• Standing work of light to moderate effort, such as nursing patient care or laundry: 3.3
• Walking around an office at a moderate pace: 3.8

Each MET above resting is about 1 kcal per kg per hour. A 70 kg adult therefore uses 21, 56, 161 and 196 kcal an hour on top of resting for those four.

Compare two 8-hour days. A whole day at a desk adds only 8 × 21 = 168 kcal. That’s little. Six hours at the desk and two walking around the office add 6 × 21 + 2 × 196 = 518 kcal. The 350 kcal gap is close to the 305 kcal between the inactive and active levels for the 35-year-old woman in the next section, and no gym is involved. I pick my activity level from a normal week of work and walking, not from whether I trained yesterday.

How do I work out how many calories I burn?

Use the 2023 National Academies equations. They were fitted to doubly labeled water measurements, the same lab method as the average above. Enter age in years, height in cm and weight in kg. The answer comes out in kcal a day, for adults 19 and over, as listed in Table 5-5 of the report.

Activity level	Women	Men
Inactive	584.90 - 7.01 × age + 5.72 × height + 11.71 × weight	753.07 - 10.83 × age + 6.50 × height + 14.10 × weight
Low active	575.77 - 7.01 × age + 6.60 × height + 12.14 × weight	581.47 - 10.83 × age + 8.30 × height + 14.94 × weight
Active	710.25 - 7.01 × age + 6.54 × height + 12.34 × weight	1,004.82 - 10.83 × age + 6.52 × height + 15.91 × weight
Very active	511.83 - 7.01 × age + 9.07 × height + 12.56 × weight	-517.88 - 10.83 × age + 15.61 × height + 19.11 × weight

Here is the sum once, for a woman aged 35, 165 cm and 70 kg at the low-active level. It reads 575.77 - 7.01 × 35 + 6.60 × 165 + 12.14 × 70, which is 575.77 - 245.35 + 1,089.00 + 849.80, or 2,269 kcal. I ran it for three adults. The question was how far the activity level moves the answer.

Adult	Inactive	Low active	Active
Woman, 35, 165 cm, 70 kg	2,103	2,269	2,408
Man, 35, 178 cm, 85 kg	2,730	2,950	3,139
Woman, 62, 160 cm, 60 kg	1,768	1,926	2,062

Values in kcal a day. Neighboring levels sit 136 to 220 kcal apart. If you can’t decide between two, keep the lower one as your working number.

These are estimates. The report lists a root-mean-square error of 246 kcal a day for women and 339 kcal for men. So the 2,269 for the first woman means roughly 2,000 to 2,500. Your own weigh-ins are the final check. If it held steady through two weeks of honest logging, your average intake is your real burn, and it overrules any equation.

The calorie calculator needs only age, height, weight and activity to give you your own number. The NASEM 2023 equations behind it set no goal below 1,200 calories on the female formula or 1,500 on the male one.

Does age, muscle or sex change how many calories I burn?

Age changes little before 60. In a pooled analysis of 6,421 people from 29 countries, expenditure adjusted for fat-free mass was stable from age 20 to 60. After that it fell by about 0.7% a year. Adjusted expenditure also stayed stable during pregnancy, though what a pregnant or breastfeeding woman should eat is for her midwife or doctor to set.

Sex shows up mostly through body composition. The same paper found no effect of sex on adult expenditure once fat-free mass and fat mass were in the model. Men in the tables burn more because they carry more fat-free mass and weigh more.

The equations add a little age and a lot of weight. At the same height, weight and activity, each year of age takes off 7.01 kcal a day for women and 10.83 for men. A decade is about 70 kcal for a woman and 108 kcal for a man. Weight counts for more. Each kilogram adds 11.71 to 12.56 kcal for women and 14.10 to 19.11 for men. Recalculating after you gain or lose 5 kg therefore moves the answer by roughly 60 kcal for women and 70 to 96 kcal for men.

Recompute your number when your weight changes by 5 kg or your job changes. A birthday alone isn’t a reason.

Will I burn fewer calories after I lose weight?

A little fewer, and the equation shows how many. Weight is a term in it, so the drop is the weight coefficient times the kilograms you lose. The 35-year-old woman at 165 cm and 70 kg, low active, has 12.14 kcal per kg in her equation. After losing 7 kg her estimate is 575.77 - 245.35 + 1,089.00 + 12.14 × 63 = 2,184 kcal. That is 85 kcal lower than the 2,269 before. Small, but real. The man at 178 cm and 85 kg has 14.94 per kg. Losing 8.5 kg, a tenth of his weight, takes him from 2,950 to 2,823 kcal, or 127 kcal less.

The gap to your old target shrinks with you. If she ate 500 kcal under her old estimate and kept eating the same amount, she would now sit 415 kcal under her new one. Hall’s 2008 model adds a second effect: it predicts that the energy held in each kilogram lost changes as more of the loss comes from lean mass.

One kilogram moves the estimate by only 12 to 19 kcal, far inside the 246 and 339 kcal typical error, so recalculating after every weigh-in buys nothing. The equation also sees only age, height and weight. It can’t tell whether your body burns more or less than the average person of your size, and only your own log can. I repeat the 28-day check from the end of this page after every 5 kg and leave the target alone in between.

How accurate is the calorie burn on my watch?

Not very, at least for energy. Stanford fitted seven wrist-worn devices to 60 volunteers who sat, walked, ran and cycled. Each was checked against a lab method. The median error in energy expenditure ranged from 27.4% to 92.6%. No device came in below 20%. Heart rate was far closer than energy for every device.

A 27.4% error on a 500 kcal workout is 137 kcal either way. That test dates from 2017, so newer watches may do better, but the direction holds: energy is the weakest number on the wrist.

Use the watch for your own trend, such as active minutes this week against last week. Don’t treat a single day’s figure as a measurement. To check a walk, compare the watch with the steps to calories calculator, which uses published MET values. The per-hour and per-step sums are in calories burned walking. One mile gets its own page: how many calories you burn walking a mile.

What should I do with my number this week?

Pick your estimate from the table or the equation. Log everything you eat for 28 days and weigh yourself the same way each morning. If the scale is flat, your logged average is your burn.

If it drifts, adjust by the drift. Multiply the change in kg by 7,700 kcal, the 3,500-per-pound rule that Hall’s 2008 analysis found fits people with a lot of body fat and overstates the need for leaner people. Divide by 28 and add it to your logged average if you lost weight, or subtract it if you gained. An average of 2,300 kcal with 0.8 kg lost gives 2,300 + 0.8 × 7,700 ÷ 28 = 2,520 kcal. That is a rough number, so use it only to see whether the equation is in the right place. Take the number to a doctor instead of this page if you are under 18, pregnant or breastfeeding, or your weight changes without a change in eating or activity.

Burn describes what you use, and what to eat is a separate decision. Calsa turns your weigh-ins into a smoothed trend instead of daily jumps and, when the trend calls for it, suggests a new goal. Whether to take it is up to you.