Calculate BMR and Daily Calorie Needs
Use this Harris-Benedict calculator to estimate your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE). Enter your details below and click calculate.
Note: This calculator provides an estimate. Real calorie needs vary with body composition, hormones, training quality, sleep, stress, and medical conditions.
What is the Harris-Benedict equation?
The Harris-Benedict equation is a classic formula used to estimate how many calories your body burns at rest. That number is called your Basal Metabolic Rate (BMR). Once you have BMR, you multiply it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE), which is your approximate maintenance calories.
If you are trying to lose fat, maintain weight, or gain muscle, this is a practical starting point. It is not perfect, but it is one of the most widely used nutrition planning tools.
How this calculator works
This calculator uses your sex, age, weight, and height to estimate BMR. You can choose either the original 1918 formula or the revised 1984 formula, then apply activity level and a goal adjustment.
Equations used
| Version | Male BMR | Female BMR |
|---|---|---|
| Original (1918) | 66.47 + (13.75 × kg) + (5.003 × cm) − (6.755 × age) | 655.1 + (9.563 × kg) + (1.850 × cm) − (4.676 × age) |
| Revised (1984) | 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age) | 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age) |
After that, the formula estimates TDEE:
TDEE = BMR × Activity Multiplier
Activity multipliers explained
- 1.2 (Sedentary): Desk-based lifestyle, very little formal training.
- 1.375 (Lightly active): Light training or movement 1–3 times per week.
- 1.55 (Moderately active): Moderate exercise 3–5 times per week.
- 1.725 (Very active): Hard training most days of the week.
- 1.9 (Extra active): High activity job plus regular intense training.
How to use your result in real life
1) Start with maintenance calories
Your maintenance estimate is where your weight should stay roughly stable over time. Track body weight for 2–3 weeks and compare to your calorie intake.
2) Adjust for your goal
- For fat loss, use a daily deficit (for example, -250 to -500 kcal/day).
- For muscle gain, use a smaller surplus (often +150 to +300 kcal/day).
- Aggressive adjustments can work short term, but are harder to sustain.
3) Recalculate as your body changes
Your calorie needs change when your body weight, activity, and training volume change. Recalculate every 4–6 weeks for better accuracy.
BMR vs TDEE: quick distinction
- BMR: Calories your body uses at complete rest for basic survival functions.
- TDEE: BMR plus movement, workouts, and daily activity.
Most people should use TDEE for meal planning, not BMR alone.
Tips to improve accuracy
- Pick the activity level honestly; this is where most estimation errors happen.
- Weigh yourself under consistent conditions (same scale, same time of day).
- Track calorie intake with realistic portion sizes.
- Use weekly weight trends, not single daily weigh-ins.
- Adjust by 100–200 calories if progress stalls for 2+ weeks.
Limitations and important notes
The Harris-Benedict method is a population-based estimate. It does not directly account for lean mass percentage, metabolic adaptation after prolonged dieting, medications, thyroid status, menopause, illness, or recovery demands from elite-level training.
If you have a medical condition, are pregnant, or have a history of disordered eating, consult a qualified healthcare professional or registered dietitian before making aggressive calorie changes.
Frequently asked questions
Is this better than the Mifflin-St Jeor equation?
Both are useful estimates. Many professionals prefer Mifflin-St Jeor for general use, but Harris-Benedict is still widely used and can be very practical when paired with tracking and weekly adjustments.
How often should I update my calorie target?
Every time your body weight changes significantly (around 2–4 kg), or your activity routine shifts, recalculate and review your average weekly trend.
Can I use this for cutting and bulking?
Yes. Use maintenance calories as your base, then apply an appropriate deficit or surplus depending on your phase and timeline.
Bottom line
The Harris-Benedict equation calculator is an excellent starting framework for nutrition planning. Treat your output as a baseline, monitor real-world results, and make small data-driven adjustments over time.