Calorie Calculator – Estimate Daily Energy, BMR & TDEE

The Calorie Calculator estimates your daily energy needs based on your age, sex, height, weight, and activity level. It uses three of the most accepted formulas — Mifflin-St Jeor, Revised Harris-Benedict, and Katch-McArdle — to calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).

Understanding your calorie requirements is the foundation of every nutrition or fitness plan — whether you want to lose weight, gain muscle, or maintain energy balance. This calculator provides accurate, science-based results in both kilocalories (kcal) and kilojoules (kJ).

Use it together with the Macro Calculator, Protein Calculator, TDEE, and BMR Calculator for a complete nutrition overview.

How to Use the Calorie Calculator

Select your preferred unit system – Metric, US, or Other.
Enter your age and gender.
Input height and weight using the chosen units.
Choose your activity level (from Sedentary to Extra Active).
(Optional) Adjust formula or output units in Settings.
Click Calculate to see your BMR and daily calorie needs.

Tip: Recalculate if your weight or activity changes by more than 5%. Energy needs shift with body composition and training load.

What Are BMR & TDEE?

BMR (Basal Metabolic Rate) is the energy your body requires to function at rest — keeping organs active and maintaining temperature.TDEE (Total Daily Energy Expenditure) adds your daily activity, exercise, and thermic effect of food to BMR, providing a full picture of how many calories you burn per day.

Example: If your BMR is 1 600 kcal and you are moderately active (factor 1.55), your TDEE ≈ 2 480 kcal/day. Eating around this amount maintains your weight.

Formulas Used in the Calculator

Formula	Equation (kcal/day)	Usage
Mifflin-St Jeor (1990)	10 × weight + 6.25 × height − 5 × age + 5 (men) / −161 (women)	Most accurate for modern populations
Revised Harris-Benedict (1984)	13.397 × weight + 4.799 × height − 5.677 × age + 88.362 (men) / + 447.593 (women)	Classic clinical equation
Katch-McArdle (1970s)	370 + 21.6 × Lean Body Mass (kg)	For athletes with known body fat %

The default formula is Mifflin-St Jeor for its balance of accuracy and simplicity. Katch-McArdle is ideal for those tracking body composition through ourBody Fat Calculator.

Activity Levels Explained

Level	Factor	Description
Sedentary	1.2	Little or no exercise, desk job
Lightly Active	1.375	Exercise 1–3 days per week
Moderately Active	1.55	Exercise 3–5 days per week
Very Active	1.725	Hard exercise 6–7 days per week
Extra Active	1.9+	Physical labor or two-a-day training

Insight: Your activity multiplier converts BMR into TDEE. Review it honestly — most people overestimate activity by 10–20%.

Calorie Deficit & Surplus Guide

Once you know your TDEE, adjust calories based on your goal:

Maintenance (100 %) = TDEE → Weight stable
Mild deficit (–10 %) → Slow, sustainable fat loss
Moderate deficit (–20 %) → Faster loss (~0.5 kg/week)
Extreme deficit (–39 %) → Short-term use only
Surplus (+10 – 20 %) → Gradual muscle gain

Note: A 500 kcal/day deficit ≈ 0.45 kg (1 lb) fat loss per week. Avoid deficits greater than 1 000 kcal without medical guidance.

Accuracy & Adjustments

All equations provide estimates within ±5–10%. Monitor weight and energy for 2–3 weeks then adjust calories up or down by 5–10 %. Your real-world metabolism depends on genetics, NEAT (non-exercise activity), sleep, and stress.

To refine your results, measure body composition with our Body Fat Calculator and apply the Katch-McArdle formula.

Nutrition & Lifestyle Strategies

1. Balanced Macronutrients

Protein 1.6–2.2 g/kg for muscle maintenance
Healthy fats 20–30 % of calories
Remaining calories from carbohydrates for energy

2. Zigzag Calorie Cycling

Alternate high- and low-calorie days to maintain metabolic rate and training performance while keeping weekly calories constant.

3. Hydration & Recovery

Drink 30–40 ml of water per kg of body weight daily.
Sleep 7–9 hours for hormonal balance and muscle repair.

Pro Tip: Combine ourCalories Burned Calculator with TDEE to track exercise output vs intake for optimal results.

Frequently Asked Questions

What’s the difference between BMR and TDEE?

BMR is resting energy use; TDEE includes movement and exercise.

How many calories should I eat to lose weight?

Aim for a 300–500 kcal/day deficit to lose 0.25–0.5 kg/week safely.

Are all calories equal?

Calorie values are the same energetically, but nutrient-dense foods support better health and satiety than processed options.

Can I gain muscle and lose fat at the same time?

Yes — through a small calorie surplus and adequate protein while progressively strength-training. Use ourOne Rep Max Calculator to plan loads.

How often should I recalculate?

Every 4–6 weeks or whenever body weight changes by ≥ 3 %.

What’s the minimum safe calorie intake?

Generally not below 1 200 kcal/day for women or 1 500 kcal/day for men without medical supervision.

References & Further Reading

Conclusion

The Calorie Calculator provides a practical and scientifically validated estimate of your daily energy needs. Use it to balance calorie intake with output, optimize training, and sustain long-term results.

Combine insights from this tool with the Macro, Protein, and Body Fat calculators to design a complete fitness and nutrition plan that works for your lifestyle.

At FreeFitnessCalculators.com, we build evidence-based health tools to make your progress measurable, achievable, and sustainable — wherever you are in the world.

Calorie Calculator — Daily Energy Needs