What is BMI and how to use this calculator?

The Body Mass Index (BMI) is a quick screening tool that estimates body fat using height and weight. It classifies results as underweight, normal, overweight, or obese and helps you track general health risk. Enter your weight (kg) and height (cm) to see your BMI and category instantly.

• Useful for weight-management checkpoints
• Not a direct measure of body fat or muscle
• Discuss results with a professional for personal advice

About BMR & daily energy needs

Your Basal Metabolic Rate (BMR) is the calories your body needs at rest for vital functions. We use the Mifflin-St Jeor equation. Choose an activity level to estimate TDEE (maintenance calories) for planning fat loss, maintenance or lean muscle gain.

• BMR = “resting calories” only
• TDEE = BMR × activity factor
• Use TDEE to set a calorie deficit or surplus

What are macros and why do they matter?

Macronutrients—protein, carbohydrates, and fats—supply energy and support recovery, hormones, and performance. Enter your daily calories and preferred percentages to convert into grams per day. This helps build balanced meal plans for goals like fat loss, maintenance, or muscle growth.

• Protein ≈ 4 kcal/g • Carbs ≈ 4 kcal/g • Fat ≈ 9 kcal/g
• Typical splits: 25/45/30 or 30/40/30
• Adjust macros to suit diet style (keto, vegetarian, etc.)

How TDEE supports your goals

Total Daily Energy Expenditure (TDEE) estimates the calories you burn across your whole day. Eat around TDEE to maintain weight, 10–20% below to lose fat, or 5–15% above to gain muscle slowly. Review activity level honestly for accurate results.

About METs & exercise calories

MET (Metabolic Equivalent of Task) values estimate exercise intensity. This tool multiplies MET × body weight × hours to approximate calories burned for walking, running, cycling, swimming, yoga and more. Use it to plan workouts or balance your daily calorie target.

How many calories during pregnancy?

This simple guide adds trimester-specific energy needs to your baseline TDEE. Nutrient quality matters more than just calories—aim for whole foods, protein, fiber, healthy fats and prenatal care. Always follow advice from your healthcare provider.

Daily hydration guide

This calculator suggests a simple daily water target using body weight. Staying hydrated supports energy, digestion, skin and training performance. Adjust for heat, sweat, altitude and pregnancy/breastfeeding. Sip regularly—thirst lags behind need.

What is “ideal weight”?

The Devine formula gives a quick reference range for medication dosing and basic planning. It’s not a rigid goal. Body composition, muscle mass and health markers are more important than any single number. Use this alongside BMI, waist measures and how you feel.

Estimate body fat at home

This method uses body measurements to estimate body fat percentage. It’s practical for tracking progress over time, though not as precise as DEXA scans. Measure consistently and at the same time of day for best comparisons.

Track central fat risk

Waist-to-Hip Ratio (WHR) is a simple marker of abdominal fat distribution and related health risk. Combine it with BMI and body fat % for a clearer picture. Reducing waist size via nutrition, steps and resistance training improves WHR over time.

Plan sleep by cycles

Adults cycle through ~90-minute sleep phases. This tool back-calculates an ideal bedtime from your wake time and chosen cycles, adding a short “time-to-sleep” buffer. Aim for consistent bed and wake times to improve energy, mood and recovery.

Turn steps into energy burn

Walking is an underrated fat-loss tool. Convert your daily steps to an approximate calorie burn for simple activity tracking. Intensity, pace and terrain change the real number—use this as a helpful estimate alongside TDEE.

Train in the right zone

Estimate your Max Heart Rate (220 − age) and a broad 50–85% target zone for cardio. Lower zones build endurance; higher zones improve speed and VO₂ capacity. Warm up well, and consult a professional if you’re new to intense training.

What is BSA used for?

Body Surface Area is commonly used in clinical settings for dosing and risk assessment. This tool uses the Mosteller formula for a quick estimate from height and weight. Always follow medical guidance for any clinical decisions.