Free Health & Fitness Calculators
12 science-backed tools — no sign-up required. Pick a tool below or scroll to explore.
BMI Calculator
Calculate your Body Mass Index (BMI) to assess whether your weight falls within a healthy range for your height. BMI is a widely used screening tool recommended by the WHO.
Your BMI:
BMR & TDEE Calculator
Find your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation — the most accurate formula for estimating calories burned at rest — and your Total Daily Energy Expenditure (TDEE) based on your activity level.
Your Results:
Calorie Calculator
Determine how many calories you need daily based on your body metrics, activity level, and fitness goal — whether you want to lose weight, maintain, or build muscle.
Your Daily Calorie Target:
Macro Calculator
Get your personalized daily macronutrient breakdown — protein, carbohydrates, and fat — based on your calorie target and fitness goal.
Your Daily Macros:
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy circumference method. All you need is a measuring tape and your height, waist, neck, and hip measurements.
Your Body Fat:
Ideal Weight Calculator
Find your ideal body weight range using four well-known medical formulas: Devine, Robinson, Miller, and Hamwi. The average of all four gives you a reliable estimate.
Your Ideal Weight:
Water Intake Calculator
Calculate how much water you should drink daily based on your body weight and activity level. Proper hydration supports metabolism, recovery, and overall health.
Daily Water Intake:
Heart Rate Zone Calculator
Calculate your 5 heart rate training zones using the Karvonen formula. Training in the right zone helps optimize fat burning, endurance, and cardiovascular fitness.
Your Heart Rate Zones:
Waist-to-Hip Ratio Calculator
Measure your waist-to-hip ratio to assess abdominal obesity and related health risks. This is a more reliable indicator of cardiovascular risk than BMI alone.
Your Waist-to-Hip Ratio:
One Rep Max Calculator
Estimate your one-rep max (1RM) using three popular formulas: Epley, Brzycki, and Lander. Just enter the weight you lifted and the number of reps performed.
Your Estimated One Rep Max:
Pace Calculator
Calculate your running or walking pace, time, or distance. Enter any two values and the calculator will compute the third. Perfect for planning your training runs.
Enter any 2 of the 3 fields above. The calculator will compute the missing value.
Your Results:
Protein Calculator
Calculate your recommended daily protein intake based on your body weight and activity goals. Adequate protein supports muscle repair, satiety, and metabolic health.
Your Daily Protein Target:
Important Disclaimer
The calculators provided on this page are for informational and educational purposes only. Results are estimates based on established scientific formulas and should not be considered medical advice. Individual health needs vary — always consult with a qualified healthcare professional, registered dietitian, or certified personal trainer before making significant changes to your diet or exercise routine. FitNtip is not responsible for any decisions made based on these calculations.
Frequently Asked Questions
Our calculators use scientifically validated formulas such as the Mifflin-St Jeor equation for BMR, the U.S. Navy method for body fat estimation, and standard WHO BMI ranges. However, they provide estimates and should not replace professional medical advice. Individual results may vary based on factors like muscle mass, bone density, and overall health conditions.
Our BMI calculator uses the standard universal formula: BMI = weight (kg) ÷ height (m)². It follows the World Health Organization (WHO) classification with four categories: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30+). While BMI is a useful screening tool for populations, it does not directly measure body fat percentage and has limitations for athletes and muscular individuals.
First, use our BMR & TDEE Calculator to find your Total Daily Energy Expenditure. This uses the Mifflin-St Jeor equation — considered the most accurate BMR formula — adjusted for your activity level. Then, use our Calorie Calculator to fine-tune for your specific goal: subtract 500 calories per day for safe weight loss (~0.5 kg/week), keep the same number for maintenance, or add 300–500 calories for lean muscle gain. We always recommend consulting a dietitian for personalized plans.
Protein requirements vary significantly by activity level and fitness goals. The general Recommended Dietary Allowance (RDA) is 0.8 g per kg of body weight for sedentary adults. For active individuals, 1.2–1.6 g/kg is commonly recommended. Athletes focused on building muscle may benefit from 1.6–2.2 g/kg. Our Protein Calculator gives you a personalized target based on your weight and specific goal. Spread your protein intake across all meals for optimal absorption.