Calculate an adult daily energy estimate
Enter typical body measurements and a usual activity pattern. This tool is for adults aged 18 years and older.
Read this safety note first
Example Data Table
These examples show how different adult inputs change the estimate. They are illustrations, not personal recommendations.
| Age | Equation category | Height | Weight | Activity | Estimated daily energy |
|---|---|---|---|---|---|
| 28 years | Female | 162 cm | 60 kg | Lightly active | 1,803 kcal/day |
| 35 years | Male | 175 cm | 75 kg | Moderately active | 2,594 kcal/day |
| 50 years | Male | 180 cm | 90 kg | Sedentary | 2,136 kcal/day |
Formula Used
The calculator uses the Mifflin–St Jeor adult equation to estimate resting energy. It then multiplies that estimate by the activity factor you select.
Female equation
Resting energy = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Male equation
Resting energy = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Daily estimate
Estimated daily energy = resting energy × activity factor
The displayed planning range is 90% to 110% of the daily estimate. It reflects normal variation. It is not a medical range or a survival threshold.
Reference: Mifflin MD and colleagues, 1990. Predictive equations estimate resting energy and can differ from direct measurement.
How to Use This Calculator
- Enter your current adult age.
- Select the adult equation category used for the calculation.
- Add your height in centimeters and weight in kilograms.
- Choose the activity level closest to a normal week.
- Select kilocalories or kilojoules for the main result.
- Press Calculate Estimate to show the result above the form.
- Use the CSV or PDF button after calculation to save a copy.
- Review the safety note before changing food intake.
Understanding Daily Energy Needs
Energy supports breathing, circulation, temperature control, movement, and thinking. Your body also needs protein, fat, carbohydrates, vitamins, minerals, and water. A calorie number alone cannot describe nutritional adequacy. It also cannot predict a personal survival limit. Energy needs change across days. Sleep, stress, illness, climate, work, and exercise can all change daily use. Use this calculator as an educational starting point. Treat the result as a planning estimate. Do not use it to justify prolonged fasting, severe restriction, or emergency food decisions.
Resting Energy and Daily Activity
Resting metabolic rate is the energy your body uses at rest. It covers essential functions such as breathing and circulation. The calculator estimates this value from adult age, height, weight, and the selected equation category. It then applies an activity factor. The result is an estimated total daily energy expenditure. This is often called maintenance energy. It is not a diagnosis. It is not a prescription. Direct measurement in a clinical setting can differ from equation estimates. The estimate may also shift after body, health, or lifestyle changes.
Choosing an Activity Level
Activity factors represent daily patterns. A sedentary setting suits mostly seated routines. Light activity includes regular walking or gentle exercise. Moderate and very active settings fit more frequent movement. Choose the setting that best reflects your typical week. Do not choose a hard day. Review the result after routines change. An active job, training block, travel schedule, or recovery period may change energy use. The displayed range allows for normal day-to-day variation. It does not replace individualized clinical assessment.
Calories Are Only One Part
Calories matter, but food quality matters too. A balanced pattern supplies energy along with key nutrients. Include foods that provide protein, fiber, essential fats, vitamins, minerals, and fluids. Spread intake through the day in a way that fits your needs. Consider appetite, culture, budget, and food access. A high calorie total may still lack important nutrients. A low calorie total can also reduce energy and nutrient intake. Seek support early if eating feels difficult, stressful, or unsafe.
When Extra Support Matters
Some situations need professional guidance. These include pregnancy, breastfeeding, adolescence, older age with unplanned weight loss, eating disorders, diabetes, kidney disease, digestive conditions, or recovery from illness. People using nutrition support or certain medicines also need individualized advice. Sudden fatigue, dizziness, fainting, rapid weight change, or difficulty getting food are important warning signs. Contact a qualified clinician, registered dietitian, or local health service. Emergency symptoms need urgent care. The safest plan is practical, nourishing, and sustainable.
Using the Result Wisely
Use the estimate to start a careful conversation. Record your usual activity and how you feel. Avoid judging one day by itself. Look for patterns over time. Keep regular meals when possible. Build choices around adequate nourishment rather than a single target. Update your inputs when your weight, routine, or life stage changes. This calculator does not replace medical testing or personal care. It organizes your inputs into an estimate. Your wellbeing deserves flexible planning and reliable support.
Frequently Asked Questions
1. Does this calculate a survival minimum?
No. It estimates adult daily energy use from a prediction equation. It cannot determine a guaranteed survival minimum or replace medical assessment during food insecurity, illness, or fasting.
2. Why does the form ask for an equation category?
The selected adult equation uses different constants for female and male categories. Those constants are part of the Mifflin–St Jeor formula used for the estimate.
3. Is the estimate exact?
No. Predictive equations can differ from direct metabolic measurement. Activity, illness, medications, sleep, body composition, and measurement error can change real daily energy use.
4. Can teenagers use this calculator?
No. It is designed for adults aged 18 and older. Children and teenagers need age-specific assessment because growth and development change energy needs.
5. Is it suitable during pregnancy or breastfeeding?
No. Pregnancy and breastfeeding require separate assessment. Energy needs can change by stage, health status, fetal growth, lactation, and clinical guidance.
6. What does resting energy mean?
Resting energy estimates the energy used for essential functions while at rest. It does not include the full energy cost of everyday movement, work, exercise, and digestion.
7. How should I choose an activity level?
Select the level closest to your average week. Avoid choosing a rare workout day. Recalculate when your work pattern, training, mobility, or routine changes.
8. Why does the result include a range?
Energy use varies from day to day. The range provides a simple planning buffer around the estimate. It does not represent a clinical nutrition prescription.
9. Are calories enough for good nutrition?
No. Food also provides protein, essential fats, carbohydrates, vitamins, minerals, fiber, and fluids. A calorie target alone cannot show whether a diet is nutritionally adequate.
10. When should I seek professional advice?
Seek support for unplanned weight loss, fainting, dizziness, eating concerns, food insecurity, chronic illness, digestive symptoms, pregnancy, breastfeeding, or any planned major dietary change.
11. Can I save my calculation?
Yes. After a valid result appears, use Download CSV for a spreadsheet-friendly file or Download PDF for a formatted summary.
Choose steady nourishment and always protect your long-term health.