How many calories do you burn a day? Resting burn, walking and what the NHS figures mean

What does burning calories mean?

A calorie is a unit of energy. In everyday British use, “calories” usually means kilocalories, written kcal. The NHS explains that energy is often shown in kcal and may also be given in kilojoules (kJ).¹ Pre-packed food labels in the UK must show energy in both kJ and kcal.³

Your body uses energy all day, including when you are asleep. The NHS puts the idea simply: to stay at about the same weight, the calories your body uses should match the calories you eat and drink, and eating more than you use leads to weight gain.¹ This guide is about the “use” side of that sum. It makes no promise about weight loss.

Two parts matter. One is the energy your body spends at rest, which researchers call resting energy expenditure. The other is the extra energy you spend on movement. The first is estimated with an equation. The second is estimated from a table of activities. Both are estimates, and this page shows how far each can be trusted.

How can you estimate your resting burn? A worked example in stones, feet and inches

The Mifflin-St Jeor equation was built from 498 healthy adults aged 19 to 78 (247 women and 251 men), whose resting energy was measured by indirect calorimetry.⁵ For women it is 10 x weight (kg) plus 6.25 x height (cm) minus 5 x age (years) minus 161. For men it is the same with plus 5 instead of minus 161. The result is kcal per day.⁵

The authors found that the older Harris-Benedict equations overestimated measured resting energy expenditure by 5%.⁵ The new equation explained a good deal of the variation between people (R2 of 0.71) but not all of it.⁵ That means two people with identical inputs can still differ.

The example

These figures are invented to show the arithmetic. A woman aged 40 weighs 11 st 4 lb and is 5 ft 7 in tall.

1. Weight: 11 st 4 lb is 11 x 14 + 4 = 158 lb. One pound is 0.45359237 kg, so 158 lb is 71.7 kg.
2. Height: 5 ft 7 in is 67 in. One inch is 2.54 cm, so 67 in is 170.2 cm. We use 170 cm.
3. Equation: 10 x 71.7 = 717; 6.25 x 170 = 1,062.5; 5 x 40 = 200. So 717 plus 1,062.5 minus 200 minus 161 gives 1,418.5 kcal a day.

So the estimate for her resting burn is about 1,419 kcal a day. For a man of the same age and measurements the equation gives 166 kcal more, because plus 5 replaces minus 161.⁵

The usual next step is to multiply by an activity factor. No source read for this guide supplies one, so this page stops at resting and uses the Compendium table below for activity. It gives a cleaner link between what you did and what it cost.

What do common activities cost?

The Compendium of Physical Activities lists activities by MET, short for metabolic equivalent. One MET is defined as 1 kcal per kilogram of body weight per hour, roughly the energy cost of sitting quietly.⁷ So energy in kcal is the MET value multiplied by your weight in kilograms and by the hours spent. The 2011 edition holds 821 codes for specific activities.⁶

The table applies that sum to 30 minutes for two weights: 71.7 kg (11 st 4 lb) and 79.4 kg (12 st 7 lb). The values include the energy you would have used anyway at rest, so they are gross figures, and they are estimates, not measurements on you.⁷

Read the table the way you would read a map scale. It tells you that thirty minutes of brisk walking costs roughly five times what sitting does, not that your own walk burned exactly 172 kcal.

The NHS 12-week guide gives 266 kcal for an hour of brisk walking at 3.5 mph for a person of 70 kg, lower than the Compendium sum above. Both are estimates.¹⁸

How many calories does walking, a mile or 10,000 steps use?

The NHS says fast walking uses more calories than walking at a moderate pace, and that a brisk walk is about 3 miles an hour, faster than a stroll.¹¹⁵

For steps, the BHF says 10,000 steps is almost five miles (eight kilometres), depending on stride length, and takes most people one to two hours in one go. It says that many steps burn between 300 and 800 calories, depending on your weight and height.¹⁴ The range is wide because weight and pace change the answer.

A mile and 10,000 steps in numbers

Take the 71.7 kg woman from above walking at 3.7 mph, which is the middle of the Compendium’s 3.5 to 3.9 mph brisk band and a choice made for this example, not a measured speed. A mile takes 60 divided by 3.7, which is about 16.2 minutes. Gross energy is 4.8 x 71.7 x (1 / 3.7), which is about 93 kcal per mile.⁸

For 10,000 steps, take almost five miles as 4.9 miles. At 3.7 mph that takes about 1.3 hours, so 4.8 x 71.7 x (4.9 / 3.7) is about 456 kcal gross. That sits inside the BHF’s 300 to 800 range.¹⁴ The Compendium sum and the BHF range agree, but both remain estimates.

The NHS guidelines are written in minutes, not steps: at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week for adults, plus strengthening activities on at least 2 days.¹⁶ The NHS page on walking describes brisk walking as a way to burn excess calories without setting a step target.¹⁵

What does the NHS say about daily calories?

The NHS says an average man needs 2,500 kcal a day and an average woman 2,000 kcal a day, and adds that the figure can differ based on age, weight, height and how much exercise a person does.¹ The NHS Better Health page gives the same averages, 2,000 for women and 2,500 for men, to stay at a healthy weight.² The gap between them is 500 kcal a day.

These are averages for a group, not targets for you. The Scientific Advisory Committee on Nutrition (SACN), in its 2011 report on energy, warns that its dietary reference values are for large groups and should not be applied to individuals, because physical activity and energy expenditure vary so much.⁴

If you are thinking of cutting back, the NHS Better Health page says to aim to reduce intake by around 600 calories a day, and to talk to a GP or healthcare professional first if you have a medical condition, a special diet or a history of eating disorders.² Note that the page is undated, so check the NHS site for the current wording.

Energy is only one part of a healthy weight. For the measures the NHS actually uses, see BMI and healthy weight and waist measurement.

Does muscle burn more than fat?

A little. Wang and colleagues re-evaluated resting metabolic rates per kilogram per day of about 13 kcal for skeletal muscle and 4.5 kcal for fat tissue.¹² The BHF puts it in everyday words: the more muscle you have, the more calories your body naturally burns, even when not exercising.¹⁷

Here is the size of the difference. Ten kilograms of muscle at rest would use 10 x 13 = 130 kcal a day, and ten kilograms of fat would use 10 x 4.5 = 45 kcal. The gap is 85 kcal a day for 10 kg of tissue. That is real, but modest. Building muscle is worthwhile for other reasons, and the NHS asks for strengthening work on at least 2 days a week,¹⁶ but it does not rewrite your daily burn.

If you want to know what your own body is made of, see the guide to body composition and the page on body fat percentage.

How accurate is the number on a watch or band?

A Stanford study tested seven wrist-worn devices on 60 volunteers. Most measured heart rate adequately, but they estimated energy expenditure poorly: no device achieved an error below 20 percent, and the authors urged caution in using the energy figures.¹³ The study dates from 2017 and covers the devices of that time, so it should not be applied to a particular current model. What it does show is that calories burned on a wrist display are an estimate with a wide margin.

A bathroom scale does not measure the calories you burn at all. It weighs you and, if it is a body composition scale, estimates measures such as body fat. Those estimates have their own margin of error, covered in the guide to smart scale accuracy.

A sensible way to use the numbers

• Use the resting estimate as a rough starting point, not a budget.
• Use the activity table to compare options, such as a walk against a bike ride, rather than to count to the last calorie.
• Weigh once a week if you weigh yourself at all. An NHS weight-loss guide warns that weight fluctuates from day to day, so daily weighing may not give a true picture.¹⁸
• Where a health professional has given you a number, use theirs.

Frequently asked questions