Free Calorie & BMI Calculator
Estimate your daily calories (TDEE), get weight-loss targets and check your BMI in seconds.
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Twelve free, evidence-based tools. Pick the one that matches what you want to know.
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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, 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. Use the TDEE calculator for a dedicated breakdown.
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. For a structured plan, try the cutting calculator.
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.
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. The protein calculator gives a tailored target. 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". See the bulking calculator for a complete plan.
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. For a more complete picture, use the body fat calculator alongside this one. Treat BMI as one data point among waist circumference, energy levels, blood markers and how your clothes fit.
Frequently asked questions
How accurate is this calorie calculator?
The Mifflin-St Jeor equation predicts BMR within roughly ±10% for most adults. The biggest source of error is the activity multiplier — people consistently over-estimate how active they are. If you're not losing weight on the predicted deficit after 2–3 weeks, drop one activity level and reassess.
What's the difference between BMR and TDEE?
BMR is the calories you burn doing nothing. TDEE is BMR plus everything else: walking, training, digesting food, even fidgeting (known as NEAT). TDEE is the number that matters for weight management because it reflects your real-world calorie burn.
How long does it take to lose 5 kg safely?
At a moderate 0.5 kg-per-week deficit, around 10 weeks. Faster is possible but rarely sustainable — most people who lose weight quickly regain it within a year. Slow, consistent loss preserves muscle and metabolic rate.
Do I really have to count calories forever?
No. Most people only need 4–8 weeks of strict tracking to internalise the calorie content of their usual meals. After that, occasional spot-checks (a week every couple of months, or whenever weight starts trending the wrong way) are usually enough to stay on track.
Is a calorie deficit the only thing that matters?
For weight loss specifically, yes — you can't lose body fat without one. But food quality, protein intake, sleep, stress and training all influence how easy the deficit feels and how much of the lost weight is fat versus muscle.
Why has my weight loss stalled?
Three usual suspects: (1) your TDEE has dropped because you're smaller — recalculate; (2) you've started eating slightly more without noticing — re-tighten tracking for a week; (3) water retention is masking real fat loss. Judge by the weekly average over 2–3 weeks, not single days.