A calorie calculator estimates daily energy needs using your resting energy estimate and an activity multiplier. It can provide a starting point for planning, but it cannot measure your metabolism directly.
How does this calorie calculator work?
This calculator uses the Mifflin–St Jeor equation to estimate basal metabolic rate (BMR), then multiplies BMR by an activity factor to estimate total daily energy expenditure (TDEE). The result is a general estimate for adults, not a medical or dietary prescription.
Calorie calculation formula
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Daily maintenance estimate: TDEE = BMR × activity factor
The activity factors used are 1.2 (sedentary), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active), and 1.9 (extra active). These are broad approximations and cannot capture every person's daily movement.
Example calorie calculation
For an illustrative 30-year-old man weighing 70 kg and measuring 170 cm, BMR is approximately 1,618 kcal/day. At an activity factor of 1.55, estimated maintenance is about 2,508 kcal/day. Your result will differ according to your inputs and selected activity level.
How should I use the result?
- Maintenance: a starting estimate for maintaining your current weight.
- Weight loss: this tool shows a modest 300 kcal/day reduction from estimated maintenance.
- Weight gain: this tool shows a modest 300 kcal/day increase from estimated maintenance.
- Review over time: estimates are best treated as a starting point and adjusted with appropriate professional guidance.
What affects calorie needs?
Body size, age, activity, body composition, sleep, medications, health conditions and individual variation can all influence energy needs. Activity labels are approximate, and people with physically demanding work may need a different estimate from people with desk-based routines.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR estimates the energy your body uses at rest. TDEE estimates total daily energy use after accounting for activity.
How many calories should I eat to lose weight?
There is no single target for everyone. This calculator offers a modest 300 kcal/day reduction from estimated maintenance as a starting illustration. A qualified healthcare professional or dietitian can help you choose a suitable target.
Is this calculator accurate?
It uses a widely used predictive equation, but all equation-based results are estimates. Your actual energy needs may differ, sometimes substantially.
Can teenagers use this calculator?
This tool is intended for adults aged 18 and over. Children and teenagers are growing and should get calorie and nutrition guidance from a qualified healthcare professional.
Can I use this calculator during pregnancy or breastfeeding?
Pregnancy and breastfeeding change nutritional needs. Do not rely on this general calculator for those situations; consult a qualified healthcare professional or dietitian.
Should I follow a very low-calorie diet?
Do not make extreme dietary changes or follow a very low-calorie diet without medical supervision. If you have a medical condition, take medication, or have a history of disordered eating, seek professional advice.
Are my measurements saved?
The calculation code on this page runs in your browser and does not submit the measurement fields to this page's server. Other browser extensions or site services may have their own behaviour.
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Health disclaimer: This tool is for general educational information only. It does not diagnose, treat or prevent any health condition and is not a substitute for advice from a qualified healthcare professional. Do not use it to determine a diet plan for pregnancy, breastfeeding, children, or a medical condition.