Calorie Calculator
Get the number you need, with the working shown.
What is the Calorie Calculator?
The Calorie Calculator estimates your daily calorie needs using the Mifflin-St Jeor equation, the formula most widely used by dietitians for estimating resting metabolic rate. Enter your sex, age, height, weight and activity level, and it returns three numbers: your BMR (calories burned at complete rest), your TDEE (total daily energy expenditure, BMR adjusted for how active you are), and a goal-adjusted target if you're trying to lose or gain weight. Every step of the calculation is shown, not just the final number, so you can see exactly how your activity level and goal shifted the result.
This is a population-average estimate, not a measurement of your individual metabolism. Two people of identical age, height, weight and sex can have genuinely different metabolic rates due to muscle mass, genetics, hormones and other factors the equation cannot see. Use the number as a starting point to adjust from based on real results over a few weeks, not as a precise target to hit exactly.
Why use a free calorie calculator?
Mifflin-St Jeor, not an outdated formula
Uses the Mifflin-St Jeor equation, generally considered more accurate for most people than the older Harris-Benedict formula it replaced in most clinical and dietetic use.
BMR, TDEE and goal target, all shown separately
See your resting metabolic rate, your maintenance calories with activity factored in, and your final goal-adjusted number as three distinct steps, not one opaque result.
Five activity levels, not a vague slider
Choose from sedentary through very active, each defined by a specific description (days of exercise per week, physical job or not) rather than a subjective label alone.
The full working shown
Every calculation — BMR, the activity multiplier applied, and the goal adjustment — is displayed as an actual equation with your numbers substituted in.
Metric and imperial units
Enter height and weight in centimetres and kilograms, or feet/inches and pounds — both convert internally to the same underlying calculation.
How do you use the Calorie Calculator?
- 1
Choose your sex and units
Sex is required because the Mifflin-St Jeor equation uses a different constant for men and women. Pick metric or imperial units to match how you know your height and weight.
- 2
Enter your age, height and weight
This equation is calibrated for adults aged 15–100 — outside that range the result becomes unreliable and the calculator will flag it.
- 3
Select your activity level
Be honest rather than aspirational — overestimating activity level is the most common reason someone's "maintenance" calories turn out to actually be a surplus.
- 4
Choose a goal
Maintain, or apply a mild or standard calorie deficit or surplus for weight loss or gain. The calculator shows your final target with the adjustment already applied.
How is calorie calculator calculated?
BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (men) or −161 (women); TDEE = BMR × activity multiplierWhere:
- weight (kg)
- Body weight in kilograms
- height (cm)
- Height in centimetres
- age
- Age in years
- +5 / −161
- A fixed constant added for men, subtracted for women, accounting for average differences in body composition
- Activity multiplier
- A factor from 1.2 (sedentary) to 1.9 (very active) applied to BMR to estimate total daily calories burned
The simple version
BMR is the number of calories your body burns just staying alive at complete rest — breathing, circulation, cell repair — calculated from your weight, height, age and sex. TDEE takes that resting number and scales it up based on how much you actually move in a day, from barely at all (sedentary) to very physically demanding (very active). Your final calorie target then adds or subtracts a fixed amount from TDEE depending on whether your goal is to lose, maintain or gain weight.
What does it look like in practice?
Maintenance calories for a moderately active man
Input
Male, 30 years, 175 cm, 75 kg, moderate activity (×1.55), maintain weight
Result
BMR = 1,699 cal · TDEE ≈ 2,633 cal · Target: 2,633 cal/day
BMR = 10×75 + 6.25×175 − 5×30 + 5 = 750 + 1,093.75 − 150 + 5 = 1,698.75. TDEE = 1,698.75 × 1.55 = 2,633.06.
Weight loss target for a lightly active woman
Input
Female, 28 years, 165 cm, 65 kg, light activity (×1.375), lose weight (−500 cal/day)
Result
BMR = 1,380 cal · TDEE ≈ 1,898 cal · Target: 1,398 cal/day
BMR = 10×65 + 6.25×165 − 5×28 − 161 = 650 + 1,031.25 − 140 − 161 = 1,380.25. The −500 goal adjustment is applied to TDEE, not BMR directly.
Mild surplus for muscle gain
Input
Male, 24 years, 180 cm, 80 kg, very active (×1.9), mild weight gain (+250 cal/day)
Result
BMR = 1,810 cal · TDEE ≈ 3,439 cal · Target: 3,689 cal/day
BMR = 10×80 + 6.25×180 − 5×24 + 5 = 800 + 1,125 − 120 + 5 = 1,810. A very active multiplier assumes hard daily exercise combined with a physically demanding job — check this genuinely matches your routine before trusting the number.
How accurate is it?
The Mifflin-St Jeor equation is widely cited in nutrition and dietetics literature as one of the more accurate predictive formulas for resting metabolic rate at the population level, but any formula using only weight, height, age and sex is estimating an average, not measuring you individually. The only way to know your true metabolic rate precisely is indirect calorimetry in a clinical or lab setting.
- This equation is calibrated for adults aged 15–100 with a broadly typical body composition — it is not designed for children, and becomes progressively less reliable at the extremes of body composition, such as very high muscle mass or very low body fat.
- Activity multiplier selection is the biggest source of real-world error in the final number — most people who plateau on a calorie target overestimated their activity level, not because the BMR formula itself was wrong.
- This is an estimate for general planning, not medical or clinical nutrition advice. It should not be used to manage a diagnosed medical condition, and is not appropriate during pregnancy or breastfeeding without guidance from a healthcare professional, since calorie needs change substantially in both cases.
- Consult a doctor or registered dietitian before starting any calorie-controlled eating plan, particularly if you have a history of disordered eating, a medical condition affecting metabolism, or are under 18.
What should you know before using it?
The five activity levels and their multipliers, applied to BMR to estimate TDEE:
| Activity level | Multiplier and description |
|---|---|
| Sedentary | ×1.2 — little or no regular exercise, a desk-based routine |
| Light activity | ×1.375 — light exercise or sports 1–3 days per week |
| Moderate activity | ×1.55 — moderate exercise or sports 3–5 days per week |
| Active | ×1.725 — hard exercise or sports 6–7 days per week |
| Very active | ×1.9 — hard daily exercise combined with a physically demanding job, or twice-daily training |
Which tools relate to the calorie calculator?
The calorie calculator is one of 21 calculators on this site. These are the ones most often used alongside it — either because they handle the next step in the same job, or because they answer a question this tool raises.
BMI Calculator
BMI screens whether your current weight falls in a typical range for your height; this calculator estimates the calories needed to maintain, reduce or increase it.
Body Fat Calculator
Body composition affects real metabolic rate more precisely than weight alone — check it alongside your calorie target for a fuller picture.
Heart Rate Calculator
Pairs with an accurate activity-level assessment — your training heart rate zones and calorie needs are both derived in part from how active you actually are.
Age Calculator
Age is a direct input to the BMR formula — confirm your exact age if you're near a birthday that would shift the calculation.
When should you use a calorie calculator?
Because the calorie calculator runs entirely in your browser, it suits work you would not want to hand to a third-party server — client files, unpublished drafts, anything under an NDA. These are the situations people reach for it in most often.
Setting a weight loss or gain target
Use the TDEE figure as a maintenance baseline, then apply a deficit or surplus as a starting point to adjust from based on real progress.
Sanity-checking a diet or meal plan
Compare a diet plan's daily calorie target against your own estimated TDEE to check whether it's realistic for your body and activity level, rather than a generic number.
Adjusting nutrition around training changes
Recalculate when your activity level genuinely changes — starting or stopping regular training meaningfully shifts your TDEE and therefore your calorie needs.
Working with a dietitian or trainer
Use the BMR and TDEE figures as a starting conversation point with a professional, who can adjust for factors this formula cannot see.
Frequently asked questions
What is the Mifflin-St Jeor equation?
What is the difference between BMR and TDEE?
How many calories should I eat to lose weight?
Why does this calculator ask for my sex?
Is this calculator accurate for athletes or bodybuilders?
Is this medical advice?
Why did my weight loss stall even though I'm eating my calculated target?
Is the calorie calculator safe to use?
This tool runs entirely inside your browser. Your text, files and settings are processed on your own device and are never uploaded to our servers — there is nothing for us to store, log or leak. You can confirm it yourself: open your browser DevTools, switch to the Network tab, and use the tool. You will not see an upload request. It also means the tool keeps working if your connection drops mid-task.
Where do these figures come from?
Every method, threshold and standard this page relies on, with a link to the document that defines it. Check them — a tool that will not show its sources is asking you to take its word for it.
- 1A new predictive equation for resting energy expenditure in healthy individuals
Mifflin MD, St Jeor ST, et al. — American Journal of Clinical Nutrition · 1990
Supports: The Mifflin-St Jeor BMR formula and its male/female constants used as the basis for this calculator.
- 2Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review
Frankenfield D, Roth-Yousey L, Compher C — Journal of the American Dietetic Association · 2005
Supports: The claim that Mifflin-St Jeor is generally more accurate than the older Harris-Benedict equation for most people.
- 3Human energy requirements: Report of a Joint FAO/WHO/UNU Expert Consultation
Food and Agriculture Organization of the United Nations · 2004
Supports: The physical activity level (PAL) multiplier ranges used to scale BMR up to TDEE.
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