Calorie Calculator (TDEE) — Find Your Daily Needs

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Calorie Calculator (TDEE): Find Your Daily Calorie Needs

Our free Calorie Calculator (TDEE) estimates your total daily energy expenditure — the number of calories your body needs each day to maintain its current weight, based on your age, sex, height, weight, and activity level. Understanding your TDEE gives you a personalised starting point for managing your weight, whether your goal is to lose, gain, or maintain. Enter your details into the calculator above to get your result in seconds.

Calculate Your Calorie(Tdee)

Your Total Daily Energy Expenditure — how many calories your body burns in a day.

ⓘ This calculator gives an estimate using the Mifflin-St Jeor equation. It is not medical advice.

What Does Your Calorie Calculator (TDEE) Result Actually Mean?

Your TDEE — total daily energy expenditure — is the estimated number of calories your body burns in a 24-hour period when all activity is taken into account. It combines your basal metabolic rate (BMR), which is the energy your body uses simply to stay alive at rest, with additional calories burned through physical activity, digestion, and other daily movement. The number your Calorie Calculator (TDEE) returns is your maintenance figure: consume roughly this many calories each day and, all else being equal, your weight is likely to remain stable.

If your goal is weight loss, a moderate calorie deficit — typically 300 to 500 kcal below your TDEE — may help you lose around 0.5 to 1 lb per week, which is considered a safe and sustainable rate by NHS guidelines. Conversely, consuming more calories than your TDEE can support muscle gain when combined with appropriate resistance training. It is important to remember that TDEE is an estimate based on population averages; individual metabolism, hormonal factors, and body composition all influence how your body responds in practice.

How Our Calorie Calculator (TDEE) Works: The Science in Plain English

Our Calorie Calculator (TDEE) uses the Mifflin–St Jeor equation, which is widely regarded as one of the most accurate formulas for estimating basal metabolic rate in adults and is recommended by the Academy of Nutrition and Dietetics. The BMR figure is then multiplied by an activity factor — known as the physical activity level (PAL) — to produce your TDEE. The activity levels used in the calculator correspond to the following descriptions:

  • Sedentary: little or no structured exercise; predominantly desk-based or inactive lifestyle (PAL ≈ 1.2)
  • Lightly active: light exercise or sport 1–3 days per week, such as walking or gentle cycling (PAL ≈ 1.375)
  • Moderately active: moderate exercise or sport 3–5 days per week, including gym sessions or brisk walking (PAL ≈ 1.55)
  • Very active: hard exercise or sport 6–7 days per week, including manual labour or intensive training (PAL ≈ 1.725)
  • Extra active: very hard daily exercise, a physically demanding job, or twice-daily training sessions (PAL ≈ 1.9)

How to Use Your TDEE Result to Reach Your Health Goals

Once you have your TDEE from the Calorie Calculator (TDEE) above, you can use it as a practical benchmark to guide your daily food intake. Rather than following a generic diet plan, working from your personal TDEE means your calorie target is tailored to your body and lifestyle, which can make it easier to stick to over time.

Setting a Calorie Target Based on Your Goal

For weight loss, most health professionals recommend aiming for a deficit of no more than 500 kcal below your TDEE per day. Larger deficits may lead to muscle loss, nutritional deficiencies, and are harder to sustain. Tracking your intake using a food diary or app alongside your TDEE result can help you stay within a healthy range without feeling excessively restricted.

For weight maintenance or muscle gain, eating at or slightly above your TDEE — combined with progressive resistance training — may support lean muscle development over time. It is worth recalculating your TDEE every four to six weeks as your weight, fitness level, or activity patterns change, since these factors all influence your total daily energy expenditure. If you have a medical condition such as hypothyroidism, type 2 diabetes, or polycystic ovary syndrome (PCOS), your calorie needs may differ from the calculator's estimate, and a consultation with your GP or a registered dietitian is advisable.

Factors That Affect Calorie Needs Beyond the Calorie Calculator (TDEE)

While our Calorie Calculator (TDEE) accounts for the most significant variables — age, sex, height, weight, and activity level — several additional factors can influence how many calories your body actually requires. Being aware of these can help you interpret your result more accurately and adjust your approach if your weight is not responding as expected.

Hormonal health plays a considerable role: conditions such as an underactive thyroid (hypothyroidism) can lower metabolic rate, meaning your actual calorie needs may be lower than the calculator suggests. Conversely, a high proportion of lean muscle mass increases BMR, since muscle tissue burns more calories at rest than fat tissue. Sleep quality, chronic stress, certain medications (including corticosteroids and some antidepressants), and the natural decline in metabolic rate with age can all shift your energy balance. If you are consistently eating at your calculated TDEE but not seeing expected changes in weight, it may be worth speaking to your GP to rule out any underlying medical causes.

Frequently Asked Questions

How accurate is a calorie calculator TDEE?
A TDEE calculator based on the Mifflin–St Jeor equation is accurate to within roughly 10% for most healthy adults, making it a reliable starting point. However, individual factors such as hormonal conditions, body composition, and genetics mean your actual needs may vary, so treat the result as an informed estimate rather than an exact figure.
How many calories should I eat a day to lose weight?
A common guideline is to consume 300–500 kcal fewer than your TDEE each day, which may support a gradual weight loss of around 0.5–1 lb per week. The NHS recommends avoiding very low-calorie diets (below 800 kcal/day) without medical supervision, as these carry risks of nutritional deficiency and muscle loss.
What is TDEE and why does it matter?
TDEE stands for total daily energy expenditure — the total number of calories your body burns in a day through all activity, including rest, digestion, and exercise. Knowing your TDEE helps you set a personalised calorie target for weight loss, maintenance, or muscle gain, rather than following a one-size-fits-all approach.
Can I use the Calorie Calculator (TDEE) if I am trying to build muscle?
Yes — to support muscle gain, you would typically aim to eat slightly above your TDEE result (a surplus of around 200–300 kcal per day) alongside a structured resistance training programme. This approach, often called a 'lean bulk', may help minimise excess fat gain while providing enough energy for muscle repair and growth.
Does the Calorie Calculator (TDEE) work for women differently than for men?
Yes — the Mifflin–St Jeor equation used in our Calorie Calculator (TDEE) applies different coefficients for biological sex, as men typically have a higher proportion of lean muscle mass and therefore a higher BMR on average. Women also have different calorie needs during pregnancy and breastfeeding, which standard TDEE calculators do not account for.
How often should I recalculate my TDEE?
It is a good idea to recalculate your TDEE every four to six weeks, or whenever your weight changes by more than a few kilograms, your activity level shifts significantly, or your fitness goals change. As you lose or gain weight, your BMR and therefore your TDEE will also change.
Is a calorie calculator TDEE suitable for teenagers?
Standard TDEE calculators are designed for adults and may not accurately reflect the higher energy demands of adolescents, who are still growing. Teenagers should seek guidance from a GP or registered dietitian rather than relying solely on an adult TDEE formula to set their calorie intake.
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the number of calories your body needs to perform basic life-sustaining functions at complete rest — such as breathing and circulation. TDEE builds on this by adding the calories burned through physical activity and digestion, giving a more complete picture of your total daily energy needs.

Sources

  1. Calories: How to maintain a healthy weight NHS [accessed 26 August 2026]
  2. The Mifflin St Jeor Equation: A New Predictive Equation for Resting Energy Expenditure Journal of the American Dietetic Association (PubMed) [accessed 26 August 2026]
  3. Obesity: identification, assessment and management (CG189) NICE [accessed 26 August 2026]
  4. Energy requirements and physical activity British Nutrition Foundation [accessed 26 August 2026]
  5. Dietary Reference Values for Food Energy and Nutrients for the United Kingdom Scientific Advisory Committee on Nutrition (SACN) / GOV.UK [accessed 26 August 2026]
  6. Comparison of predictive equations for resting metabolic rate in healthy adults Journal of the Academy of Nutrition and Dietetics (PubMed) [accessed 26 August 2026]
  7. Physical activity guidelines for adults aged 19 to 64 NHS [accessed 26 August 2026]
  8. Energy balance and body weight regulation Proceedings of the Nutrition Society (Cambridge University Press) [accessed 26 August 2026]
  9. Weight management: lifestyle services for overweight or obese adults (PH53) NICE [accessed 26 August 2026]
  10. Eat well — The Eatwell Guide NHS [accessed 26 August 2026]

This calculator provides an estimate for general informational purposes only and is not medical advice. Always consult a qualified healthcare professional before making changes to your diet or starting any weight loss treatment.