Calorie Calculator — Maintenance, Weight Loss & TDEE

How this calorie calculator works

Every plan starts with one number: how much energy your body uses in a day. The calculator finds that in two steps. First it estimates your Basal Metabolic Rate (BMR) — the calories you would burn if you did nothing but rest for 24 hours. Then it multiplies that figure by an activity factor to give your Total Daily Energy Expenditure (TDEE), which is the number of calories that keeps your weight steady.

Once you know your maintenance number, changing your weight becomes simple maths. Eat below it and your body draws on stored fat, so you lose weight. Eat above it and you gain. Because roughly 3,500 calories is stored in about half a kilogram (one pound) of body fat, a daily gap of 500 calories works out to about half a kilo of change per week.

Which formula should you pick?

The tool offers the three equations trusted by nutrition professionals. Each estimates BMR slightly differently:

If you are unsure, leave it on Mifflin-St Jeor. It needs only your age, sex, height and weight, and it is the option most experts reach for first.

Activity levels explained

The activity factor is where most people go wrong, usually by overestimating. Be honest — desk work with a couple of gym sessions is "light", not "very active".

How many calories to lose weight — safely

A gentle deficit is the one you can actually keep. Trimming 250–500 calories a day is comfortable for most people and protects muscle. Larger cuts speed things up but get harder to sustain and can leave you tired. A useful floor to remember: many health bodies suggest not dropping below about 1,200 calories a day for women or 1,500 for men without professional guidance, because very low intakes make it hard to get enough nutrients.

Weight also naturally bounces day to day with water and food in your system, so judge progress over a week or two rather than the daily scale reading. Pair the number with mostly whole foods and enough protein, and the results tend to stick.

The zigzag plan (beat the plateau)

Eating the exact same calories every day can cause progress to stall as your body settles into the routine. Zigzag cycling keeps the weekly total identical but varies each day — a few higher days and a few lower ones. That flexibility makes social meals easier and can help keep fat loss moving. A simple way to try it: take your daily loss target, add about 200 calories on three "high" days, and trim the remaining four "low" days so the seven-day total still matches.

Protein & GLP-1: protecting muscle while losing fat

The biggest shift in weight management right now is the rise of GLP-1 medications such as Ozempic, Wegovy, Mounjaro and Zepbound. They work by lowering appetite, which makes a calorie deficit almost effortless. But that same appetite drop creates a new problem: many people end up eating too little and losing muscle alongside fat — and muscle is what keeps your metabolism strong.

The fix is protein. Research on weight loss consistently points to a target of roughly 1.2–1.6 grams of protein per kilogram of body weight per day to preserve lean muscle during a deficit — well above the basic 0.8 g/kg baseline. Turn on GLP-1 mode above and the calculator highlights your protein target and a safe-minimum calorie line, so the goal becomes eating enough of the right things, not simply eating as little as possible.

This matters whether or not you take medication: hitting your protein number and keeping calories at a sensible floor is the same principle that protects muscle for anyone losing weight. As always, this is general education, not a treatment plan — your doctor or dietitian can tailor it to you.

Calories burned by common activities (per 30 minutes)

Exercise is a helpful nudge, but it is smaller than most people expect — which is why intake matters most. Rough guide for a 70 kg adult:

Roughly how many calories a day, by age and sex

These are ballpark maintenance ranges from national dietary guidance. They are averages for a moderately active person — your own number from the calculator above will be more personal, but this gives you a quick sanity check.

Notice the numbers drift down with age. That is mostly because we tend to lose muscle and move a little less over the years — which is exactly why protein and strength work matter more, not less, as you get older.

Calories in everyday foods

Counting calories gets far easier once you have a feel for what common foods cost you. The figures below are typical values for a normal serving — brands and portion sizes vary, so treat them as a guide rather than a lab measurement.

A quick lesson hides in that list: fats such as oil, cheese and nuts pack the most calories into the smallest space, while vegetables give you volume and fibre for very little. Building meals around lean protein and plenty of vegetables is the simplest way to feel full on fewer calories.

Not every calorie is equal

A calorie is just a unit of energy, so on a pure maths level 200 calories of soda and 200 calories of chicken and rice affect your weight the same way. In real life, though, they behave very differently. Protein and fibre keep you satisfied for hours and cost a little energy just to digest, while sugary drinks and refined snacks are absorbed fast and tend to leave you hungry again soon after.

These fast, low-nutrition calories are often called empty calories — energy with very little protein, fibre, vitamins or minerals attached. You do not have to cut them out completely, but the more of your daily total comes from whole, minimally processed foods, the easier it is to stay full, hit your protein target and keep your results without feeling deprived.

General guidance only — not medical advice.

Sources & methods: BMR equations from Mifflin & St Jeor (1990), the revised Harris-Benedict equation, and Katch-McArdle lean-mass method; calorie-per-day ranges based on national dietary guidance; food energy values based on standard nutritional databases. Figures are rounded population estimates.