Calorie Calculator
Estimate your daily calorie needs (BMR and TDEE) based on your height, weight, age and activity level.
About the Calorie Calculator
Our Calorie Calculator estimates your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, a widely used formula among dietitians. It gives a general estimate of how many calories your body uses, which you can use as a starting point for maintaining, gradually losing, or gradually gaining weight.
What Is BMR and TDEE?
BMR (Basal Metabolic Rate) is roughly how many calories your body would use in a day at complete rest, just to keep basic functions like breathing and circulation going. TDEE (Total Daily Energy Expenditure) takes your BMR and multiplies it by an activity factor to estimate your total calorie needs including movement and exercise. TDEE is generally the more useful figure day-to-day, since it reflects your actual maintenance calories.
The Mifflin-St Jeor Formula
| Sex | Formula |
|---|---|
| Men | BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5 |
| Women | BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161 |
Activity Multipliers
| Activity Level | Multiplier |
|---|---|
| Sedentary (little or no exercise) | ×1.2 |
| Lightly active (light exercise 1–3 days/week) | ×1.375 |
| Moderately active (moderate exercise 3–5 days/week) | ×1.55 |
| Very active (hard exercise 6–7 days/week) | ×1.725 |
| Extremely active (physical job or twice-daily training) | ×1.9 |
How to Use the Calorie Calculator
- Select your sex and choose Metric or Imperial units.
- Enter your age, height and weight.
- Choose the activity level that best matches your typical week.
- Choose a goal — Maintain, Lose, or Gain Weight. For Lose or Gain, pick a gradual or moderate weekly rate.
- Your BMR, TDEE, and goal calories are calculated automatically, along with a full breakdown.
A Note on Weight Loss and Gain Rates
NHS guidance suggests a typical weight-loss target of around 0.5–1kg a week is generally considered safe for most adults. This calculator deliberately limits its options to a more conservative 0.25–0.5kg a week for weight loss or gain, rather than offering faster rates. Gradual weight changes can be easier to sustain than more rapid changes. If a calculated target looks unusually low, the calculator will flag this clearly rather than presenting it as something to simply follow. For weight gain, the calculated figure is only an approximate energy estimate — actual weight change varies between individuals based on factors such as metabolism, activity levels and body composition.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR is the estimated number of calories your body needs at complete rest. TDEE builds on BMR by factoring in your activity level, giving a more realistic estimate of your total daily calorie needs, including movement and exercise.
How accurate is this calorie calculator?
The Mifflin-St Jeor equation is considered one of the more accurate general formulas, but it’s still an estimate based on population averages. Individual results can vary due to genetics, muscle mass, medical conditions such as thyroid disorders, and medications. It’s a useful starting point, not an exact figure.
Why does this calculator ask for my sex?
The Mifflin-St Jeor formula uses sex because, on average, men and women differ in muscle and fat composition, which affects resting metabolic rate. This is a component of the calculation formula, not a judgement about how you identify.
Why does the calculator only offer slow or moderate weight change rates?
Gradual rates of around 0.25–0.5kg per week are generally more sustainable and less likely to require an extreme calorie target than faster rates. This calculator intentionally doesn’t offer faster options.
What if my calculated calorie target seems very low?
If your target looks unusually low, the calculator will show a clear warning. Appropriate minimum calorie intakes vary between individuals, but a target this low is generally only followed with appropriate medical or dietetic supervision — speak to a GP or registered dietitian rather than pursuing a very low target on your own.
Is this calculator suitable for everyone?
No. It’s intended for adults aged 18 and over and doesn’t apply to children, teenagers, pregnancy, or breastfeeding. It also doesn’t account for medical conditions that affect metabolism. If you have a history of disordered eating or find calorie counting unhelpful, it’s best to speak to a GP rather than rely on a tool like this.