Calorie Calculator

Free Calorie Calculator

The Toolts Calorie Calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, widely regarded as the most accurate formula for estimating calorie needs. Enter your age, gender, weight, height, and activity level to get personalized targets for weight loss, maintenance, and weight gain, along with a suggested macronutrient breakdown.

How Your Daily Calorie Needs Are Calculated

First, the calculator determines your Basal Metabolic Rate (BMR) — the number of calories your body burns at rest just to keep you alive. For men, the Mifflin-St Jeor formula is BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161 + 166. For women, the constant is lower. Your BMR is then multiplied by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active) to estimate your TDEE, which represents the total calories you burn in a day including physical activity.

Calories for Weight Loss

To lose weight, you need to eat fewer calories than you burn, creating a calorie deficit. A deficit of 500 calories per day leads to approximately one pound (0.45 kg) of fat loss per week. This calculator shows your maintenance calories minus 500 as a sustainable weight loss target. Going below 1,200 calories per day for women or 1,500 for men is generally not recommended without medical supervision, as it can lead to nutrient deficiencies and metabolic slowdown.

Calories for Muscle Gain

Building muscle requires a calorie surplus — eating more than you burn so your body has extra energy to build new tissue. A surplus of 300 to 500 calories per day, combined with resistance training and adequate protein intake, is the most effective approach for lean muscle gain. Larger surpluses tend to increase fat gain without significantly speeding up muscle growth.

Understanding Macronutrients

Macronutrients — protein, carbohydrates, and fat — are the three main sources of calories. Protein provides 4 calories per gram and is essential for muscle repair and growth. Carbohydrates provide 4 calories per gram and are your body's preferred energy source. Fat provides 9 calories per gram and is crucial for hormone production and nutrient absorption. A balanced split of 30% protein, 40% carbs, and 30% fat works well for most active adults, though individual needs may vary based on goals and preferences.

Tips for Accurate Tracking

Calorie calculators provide estimates, not exact numbers. Individual metabolism varies based on genetics, muscle mass, hormones, and other factors. Use this calculator as a starting point, then adjust based on real results over 2 to 4 weeks. If you are not losing weight at your target calories, reduce by 100 to 200 calories. If you are losing too fast or feeling low energy, increase slightly. Consistency and patience matter more than precision.