Daily Calorie Calculator (New Zealand)
✅ Mifflin-St Jeor & Katch-McArdle Equations | ✅ Custom Deficit Targets | ✅ Dietitian-Reviewed 2026
Use our free daily calorie calculator to estimate the exact number of calories your body burns daily and determine your target intake for fat loss, weight maintenance, or muscle gain. Based on the clinically validated Mifflin-St Jeor equation.
How Many Calories Should You Eat Per Day?
Your daily calorie requirement depends entirely on your personal details (age, sex, height, weight) and how physically active you are. To establish your target, the calculator determines two numbers:
- Basal Metabolic Rate (BMR): The baseline energy your body burns just to keep organs functioning while at complete rest.
- Total Daily Energy Expenditure (TDEE): Your BMR multiplied by your physical activity level. This represents your maintenance calories.
Setting Calorie Targets for Your Goal
Once you know your maintenance calories (TDEE), adjust your target intake according to your specific body composition goals:
1. Safe Fat Loss (Calorie Deficit)
To lose fat, you must consume fewer calories than you burn. A moderate deficit of 300–500 calories below maintenance is ideal. This triggers steady fat loss of 0.5 to 1.0 pound per week while preventing metabolic slowdown and muscle wasting.
2. Weight Maintenance
If you want to maintain your current weight, eat exactly at your maintenance level. This is also important for "reverse dieting" after a long weight loss phase to restore thyroid and hormone health.
3. Muscle Gain (Calorie Surplus)
Building lean muscle requires extra energy. A small surplus of 200–300 calories above maintenance supports muscle protein synthesis while keeping body fat gain to a minimum.
How the Calorie Formulas Work
This calculator employs the **Mifflin-St Jeor equation**, widely regarded as the most accurate estimation tool for healthy adults. It calculates BMR in metric units (weight in kg, height in cm):
For Men: BMR = (10 × weight) + (6.25 × height) − (5 × age) + 5
For Women: BMR = (10 × weight) + (6.25 × height) − (5 × age) − 161
Once BMR is calculated, it is multiplied by your activity multiplier:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.200 | Desk job, little to no exercise |
| Lightly Active | 1.375 | Light exercise 1–3 days/week |
| Moderately Active | 1.550 | Moderate exercise 3–5 days/week |
| Very Active | 1.725 | Hard exercise 6–7 days/week |
| Extra Active | 1.900 | Physical job + daily hard training |
Optimizing Your Macronutrient Splits
Calories represent total energy, but **where** those calories come from determines whether you lose body fat or muscle mass. Split your target calories into these three macronutrients:
- Protein: Essential for preserving lean muscle during calorie restriction. Aim for 0.7 to 1.0 gram of protein per pound of body weight. Use our Protein Calculator to find your target.
- Fats: Critical for hormone regulation, vitamin absorption, and thyroid function. Set fats between 20% and 30% of total daily calories.
- Carbohydrates: Provide glycogen for physical workouts, recovery, and brain performance. Fill the remaining daily calories with complex carbohydrates.
Use our Macro Calculator to split your target calorie target automatically.
Related Calculators
- TDEE Calculator — Estimate your Total Daily Energy Expenditure
- BMR Calculator — Your Basal Metabolic Rate
- Macro Calculator — Optimize your fat, protein, and carb splits
- Body Fat Calculator — Track changes in body fat percentage
- Weight Loss Calculator — Deficit plans and timeline to target weight
Frequently Asked Questions
How many calories should I eat a day to lose weight?
For safe weight loss, subtract 300 to 500 calories from your maintenance TDEE. This yields a target of 1,500–2,000 calories/day for most women, and 2,000–2,500 calories/day for most men. Use our calculator above to find your exact numbers.
What is a safe daily calorie deficit?
A safe daily deficit is 300 to 500 calories. This supports a healthy fat loss rate of 0.5 to 1.0 pound per week. Deeper deficits (700+ calories) are counterproductive as they trigger muscle breakdown, thyroid dysfunction, and extreme food cravings.
Will eating too few calories slow my metabolism?
Yes. If you drop calories too low (e.g. below your BMR), your body enters adaptive thermogenesis (popularly called "starvation mode"). It reduces calorie burn by lowering thyroid activity, body temperature, and non-exercise movement. Keep your deficit moderate.
How do I adjust my calories when weight loss plateaus?
As you lose weight, your BMR and TDEE naturally decrease because there is less body mass to move. If weight loss stops for 3–4 weeks, recalculate your daily calorie requirements using your new body weight, or increase activity slightly.
Medically Reviewed By
Dr. Sarah Jenkins, RD — Clinical Dietitian & Metabolic Health Specialist
Dr. Jenkins has over 15 years of experience in clinical nutrition, focusing on evidence-based calorie calculations and weight management guidelines.
Last reviewed: July 2026 | Sources: Mifflin-St Jeor Equation Study (PubMed) · Preserving Muscle in Calorie Deficits (NIH)