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Calorie Calculator — Daily Calorie Needs for Weight Loss & Gain

Calculate your daily calorie needs using the Mifflin-St Jeor equation. Get personalized targets for weight loss, maintenance, and muscle gain. Free, no sign-up.

What is the Calorie Calculator?

The calorie calculator estimates how many calories you need each day based on your body measurements and lifestyle. It uses the scientifically validated Mifflin-St Jeor equation to calculate your Basal Metabolic Rate (BMR), then factors in your activity level to give you a personalized maintenance calorie target — plus tailored goals for weight loss or muscle gain.

Calorie Calculator Formula

BMR (male) = 10 × weight_kg + 6.25 × height_cm − 5 × age + 5 BMR (female) = 10 × weight_kg + 6.25 × height_cm − 5 × age − 161 Maintenance = BMR × activity multiplier • Sedentary: × 1.200 • Lightly active: × 1.375 • Moderately active: × 1.550 • Very active: × 1.725 • Extra active: × 1.900

Calorie Calculator Example

A 30-year-old woman, 165 cm, 65 kg, moderately active: BMR = 10 × 65 + 6.25 × 165 − 5 × 30 − 161 = 1,402 kcal Maintenance = 1,402 × 1.55 = 2,173 kcal/day For weight loss: 2,173 − 500 = 1,673 kcal/day

How to Use the Calorie Calculator

  1. 1Enter your weight, height, age, and biological sex. These four values go into the Mifflin-St Jeor equation to calculate your BMR.
  2. 2Select your activity level — be honest. Most people overestimate their activity. 'Sedentary' is appropriate if you sit most of the day even if you exercise 3× per week.
  3. 3Choose your goal (lose, maintain, or gain) and click Calculate. You'll see your personalized calorie target and a macro breakdown for protein, fat, and carbohydrates.

Frequently Asked Questions

How many calories should I eat per day?
It depends on your weight, height, age, sex, and activity level. This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies it by your activity factor. For most adults, the result ranges from 1,600 to 3,000 kcal/day.
What is BMR and how is it different from TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and organs functioning. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. This calculator shows your TDEE as 'Maintenance Calories'.
How many calories should I eat to lose weight?
A deficit of 500 kcal/day leads to approximately 0.5 kg (1 lb) of fat loss per week. This calculator shows three deficit options: Mild (−250 kcal), Standard (−500 kcal), and Extreme (−1,000 kcal). Extreme deficits are not recommended without medical supervision — a standard deficit of 500 kcal is the safe, evidence-based approach.
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation (1990) is the most accurate formula for estimating BMR in adults, according to the Academy of Nutrition and Dietetics. The formula is: Men: BMR = 10W + 6.25H − 5A + 5; Women: BMR = 10W + 6.25H − 5A − 161. Where W = weight in kg, H = height in cm, A = age in years.
How should I split my macros for weight loss?
For weight loss, prioritize protein (at least 1.6–2.0g per kg of body weight) to preserve muscle mass. This calculator sets protein at 2.0g/kg, fat at 25% of calories, and fills the remainder with carbohydrates. Adjusting these ratios to your preferences is fine — total calorie deficit matters most for fat loss.

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Trusted Sources & Methodology

↗World Health Organization (WHO) — Global health standards and BMI classifications
↗Centers for Disease Control (CDC) — US health guidelines and population data
↗National Institutes of Health (NIH) — Medical research and clinical guidelines
↗Mayo Clinic — Trusted clinical information and health advice

API Access

Coming Soon
https://api.solviqlab.com/v1/calorie-calculator

REST API for developers. Integrate this tool into your app.

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