Free Calorie & BMI Calculator

Estimate your daily calories (TDEE), get weight-loss targets and check your BMI in seconds.

How many calories should you eat per day?

The honest answer is: it depends on your body, your goals and how much you move. Most adults need somewhere between 1,600 and 3,000 calories a day, but that range is wide because daily energy expenditure is highly individual. A free calorie calculator like this one gives you a personalised baseline in seconds, using the same Mifflin-St Jeor equation that registered dietitians and academic studies treat as the most accurate predictive formula for resting metabolism.

Your number has two parts. First is your basal metabolic rate (BMR) — the calories your body burns at complete rest just keeping you alive, which accounts for roughly 60–70% of your total burn. Second is everything you do on top of that: walking, working, training, even fidgeting. Add it all up and you get your total daily energy expenditure (TDEE), also called your maintenance calories. Eat at TDEE and your weight stays stable. Eat below it and you lose weight. Eat above it and you gain.

How a calorie deficit actually causes weight loss

Weight loss isn't about a specific food, a fasting window, or a trendy macro split — it's about energy balance. To lose body fat you need to consistently eat fewer calories than you burn, creating what's known as a calorie deficit. Around 7,700 kcal equals roughly one kilogram of body fat, so a daily deficit of 500–550 kcal produces about 0.5 kg of fat loss per week — the rate most clinicians consider both safe and sustainable.

Choosing the right deficit size

• Mild deficit (~275 kcal/day): roughly 0.25 kg / 0.5 lb per week. Easy to maintain, minimal hunger, ideal if you have less than 5 kg to lose.
• Moderate deficit (~550 kcal/day): roughly 0.5 kg / 1 lb per week. The sweet spot for most people — fast enough to stay motivated, slow enough to protect muscle.
• Aggressive deficit (~1,100 kcal/day): roughly 1 kg / 2 lb per week. Only suitable for higher starting body-fat levels and short blocks; risks muscle loss, fatigue and rebound eating.

As a general rule, women shouldn't drop below ~1,200 kcal/day and men below ~1,500 kcal/day without medical supervision — you simply can't fit enough protein, fibre and micronutrients into a smaller budget.

Why calorie tracking works (the research)

Counting calories has a reputation for being tedious, but the evidence behind it is genuinely strong. Dietary self-monitoring is consistently described in the scientific literature as the "cornerstone" of behavioural weight-loss treatment, and the data on app-based tracking is striking:

• People who logged their food on at least 6 of 7 days lost an average of 2.1 kg more at six months than inconsistent trackers.
• Consistent trackers were over three times more likely to hit a clinically meaningful 5% body-weight loss at three and six months.
• Frequency matters more than detail. Logging quickly several times a day beats writing a perfect food diary once.

The hidden benefits of counting calories

Beyond the numbers, tracking surfaces patterns you'd otherwise miss — the 300-calorie latte you forgot about, the weekend drift, the meals where protein quietly disappears. It turns vague feelings ("I think I ate okay today") into objective data, and that visibility is what drives behaviour change. Most people only need to track strictly for a few weeks to learn the rough calorie cost of their go-to meals; after that, periodic check-ins are usually enough to stay on course.

Using your TDEE: weight loss, maintenance or muscle gain

To lose weight

Subtract 15–25% from your TDEE. Prioritise protein (around 1.6–2.2 g per kg of body weight) to preserve lean muscle, eat plenty of fibre to manage hunger, and re-run this calculator every 4–6 kg of progress — your maintenance calories drop as you get smaller.

To maintain weight

Eat at your TDEE and watch the weekly average on the scale, not daily fluctuations. Water, sodium and glycogen can swing the number by 1–2 kg without any change in body fat.

To gain muscle

Add 5–10% to your TDEE alongside a structured resistance-training programme. A small surplus (around 200–300 kcal/day) maximises muscle gain while minimising fat gain — the so-called "lean bulk".

Understanding your BMI and what it really means

Body Mass Index (BMI) is a quick screening tool that compares your weight to your height. The healthy range is 18.5–24.9, with values below 18.5 classed as underweight and 25 or above as overweight. Higher BMIs are associated with greater risk of cardiovascular disease, type 2 diabetes, several cancers and joint problems — but it's a population-level statistic, not a diagnosis.

BMI doesn't distinguish between fat and muscle, so very athletic people often score "overweight" despite low body-fat percentages. It also doesn't account for fat distribution, which matters: visceral fat around the abdomen carries more health risk than fat stored on the hips and thighs. Treat your BMI as one data point alongside waist circumference, energy levels, blood markers and how your clothes fit.

Frequently asked questions