Free HealthCalculators
Explore Fitlydoo's growing collection of free health calculators designed to help you better understand your nutrition, metabolism, hydration, fitness, and overall wellness. Each calculator is easy to use, mobile-friendly, and provides clear explanations of your results.
All calculators
Health Calculators
Calorie Calculator
Find your daily calorie target for weight loss, maintenance, or muscle gain.
Use CalculatorCalorie Deficit Calculator
Project your fat loss timeline, goal date, and daily calorie intake from a safe deficit pace.
Use CalculatorProtein Calculator
Discover how much protein you need daily based on your weight and goals.
Use CalculatorWater Intake Calculator
Calculate your optimal daily hydration based on activity and climate.
Use CalculatorTDEE Calculator
Measure your total daily energy expenditure across all activity levels.
Use CalculatorMacro Calculator
Break your daily calories into the right protein, carb, and fat targets.
Use CalculatorBody Fat Calculator
Estimate your body fat percentage at home with the U.S. Navy tape-measure method.
Use CalculatorLean Body Mass Calculator
Calculate your lean body mass and fat mass from body fat % or the Boer formula.
Use CalculatorOne Rep Max Calculator
Estimate your 1RM from a submaximal set and get a full percentage-based training table.
Use CalculatorTarget Heart Rate Zone Calculator
Calculate your max heart rate and five training zones with the Karvonen formula.
Use CalculatorHeart Rate Recovery Calculator
Calculate your 1-minute heart rate recovery and learn the research context behind the 12 bpm threshold.
Use CalculatorRunning Pace Calculator
Calculate running pace, even-split race checkpoints, and predicted finish times with Riegel's formula.
Use CalculatorIdeal Weight Calculator
Calculate your ideal body weight with Devine, Robinson, Miller, and WHO formulas, adjusted for frame size.
Use CalculatorWaist-to-Height Ratio Calculator
Calculate your Waist-to-Height Ratio and see your cardiometabolic risk tier — the visceral-fat metric that beats BMI.
Use CalculatorWaist-to-Hip Ratio Calculator
Calculate your Waist-to-Hip Ratio and see a reference interpretation of your body-fat distribution.
Use CalculatorSleep Cycle Calculator
Find the best time to wake up or go to bed using 90-minute ultradian sleep cycles and reduce sleep inertia.
Use CalculatorAlcohol Calorie & Sugar Calculator
Calculate the calories, sugar, and pure alcohol in beer, wine, shots, and cocktails — with a junk-food equivalent.
Use CalculatorPregnancy Weight Gain Calculator
Track healthy pregnancy weight gain week by week using IOM and ACOG guidelines — for single babies and twins.
Use CalculatorCaffeine Half-Life Calculator
Estimate caffeine remaining at bedtime, your recommended caffeine cutoff time, and sleep-readiness risk.
Use CalculatorCreatine Dosage Calculator
Calculate your creatine loading phase dose, daily maintenance dose, and extra water intake by body weight.
Use CalculatorFFMI Calculator
Calculate your Fat-Free Mass Index and normalized FFMI to measure muscularity against the natural genetic limit.
Use CalculatorIntermittent Fasting Calculator
Map your 16:8, 18:6, 20:4, 14:10, or custom fasting schedule with a 24-hour visual timeline and workout timing.
Use CalculatorSweat Rate Calculator
Measure fluid loss, hourly sweat rate, drinking schedule, and post-workout rehydration target with sodium guidelines.
Use CalculatorReverse Dieting Calculator
Build a step-by-step post-diet calorie increase schedule and estimate weeks back to maintenance without regaining fat.
Use CalculatorMeal Macro Split Calculator
Break your daily protein, carbs, and fat into per-meal targets with MPS thresholds, workout skew, and visual macro ratios.
Use CalculatorVO2 Max Calculator
Estimate your aerobic capacity with the Rockport 1-mile walk or Cooper 12-minute run test and see your ACSM fitness classification.
Use CalculatorSteps to Calories Calculator
Estimate how many calories you burn from walking based on your step count, body weight, height, and walking pace.
Use CalculatorCalories Burned Calculator
Estimate calories burned during walking, running, cycling, swimming, gym, sports, and everyday activities using Compendium MET values.
Use CalculatorWalking Calories Calculator
Estimate calories burned walking — leisurely, moderate, brisk, uphill, downhill, treadmill, and Nordic walking — using 2024 Compendium MET values.
Use CalculatorCycling Calories Calculator
Estimate calories burned cycling — road, stationary bike, spin class, mountain biking, and e-bike — using 2024 Compendium MET values.
Use CalculatorSwimming Calories Calculator
Estimate calories burned swimming — freestyle, breaststroke, backstroke, butterfly, leisurely, open-water, and treading water — using 2024 Compendium MET values.
Use CalculatorStair Climbing Calories Calculator
Estimate calories burned climbing stairs — general, slow, fast, two steps at a time, and descending — using 2024 Compendium MET values.
Use CalculatorDaily Step Goal Calculator
Build a personalized, progressive daily step target from your current activity — not a universal 10,000-step rule.
Use CalculatorBody Water Calculator
Estimate your total body water volume and percentage of body weight using the Watson equations.
Use CalculatorBrowse by category
Find the Right Calculator
Every calculator is grouped by topic so you can find exactly what you need.
Fasting & Meal Timing
Metabolism
Fitness
- One Rep Max Calculator
- Target Heart Rate Zone Calculator
- Heart Rate Recovery Calculator
- Running Pace Calculator
- Creatine Dosage Calculator
- VO2 Max Calculator
- Steps to Calories Calculator
- Calories Burned Calculator
- Walking Calories Calculator
- Cycling Calories Calculator
- Swimming Calories Calculator
- Stair Climbing Calories Calculator
- Daily Step Goal Calculator
Sleep & Recovery
Lifestyle
Pregnancy
Why choose Fitlydoo
Why Use Fitlydoo?
Built for real people who want straightforward, reliable health insights.
Fast & Easy to Use
Enter a few details and get your results instantly — no sign-up required.
Free Forever
Every calculator on Fitlydoo is completely free to use, always.
Mobile Friendly
Designed to work beautifully on any screen — phone, tablet, or desktop.
Trusted Calculation Methods
Results are based on widely accepted scientific formulas used by health professionals.
How it works
How Our Health Calculators Work
Fitlydoo calculators use widely accepted scientific formulas and established calculation methods — including the Mifflin-St Jeor equation and WHO hydration guidelines — to provide educational estimates based on the information you enter.
Important: All results provided by Fitlydoo calculators are for informational and educational purposes only. They are not a substitute for professional medical or nutritional advice. Always consult a qualified healthcare professional before making significant changes to your diet or exercise routine.
Enter your details
Provide basic information such as your age, weight, height, and activity level.
Choose your goal
Select whether you want to lose weight, maintain, gain muscle, or simply understand your baseline.
Get instant results
Your personalised estimate is calculated instantly using evidence-based scientific formulas.
Questions answered
Frequently Asked Questions
Yes — every calculator on Fitlydoo is completely free to use. There are no subscriptions, hidden fees, or paywalls. You can use any calculator as many times as you like at no cost.
Fitlydoo calculators use well-established scientific formulas — such as the Mifflin-St Jeor equation for calorie and BMR calculations — that are widely used by health professionals and researchers. They provide reliable educational estimates, though individual results can vary based on factors like body composition and genetics.
Absolutely. All Fitlydoo calculators are fully mobile-friendly and designed to work seamlessly on smartphones, tablets, and desktop computers. The layout adapts automatically to your screen size.
No account is needed. You can use any calculator on Fitlydoo without creating a profile or logging in. Just enter your details and get your results instantly.
Fitlydoo does not store your personal health data. Results are calculated in real time in your browser and are not saved to any server or database. Your information remains private.
If you are new to tracking your health and nutrition, we recommend starting with the Calorie Calculator or TDEE Calculator to understand your daily energy needs. From there, the Macro Calculator and Protein Calculator can help you optimise your nutrition for your specific goals.
We regularly review our calculators to ensure they reflect current, evidence-based formulas and guidelines. Any updates to calculation methods or features are made to improve accuracy and usability.
No. Fitlydoo calculators are educational tools designed to provide general health estimates. They are not intended to diagnose, treat, or replace professional medical or nutritional advice. Always consult a qualified healthcare professional for personalised guidance.
Health resources
Explore More Health Resources
We are building a library of in-depth articles covering nutrition, fitness, hydration, metabolism, and healthy living — designed to work alongside our calculators.
Understanding Calories
What calories are, how they work, and why they matter for your health.
Coming soonHow Much Protein Do You Need?
A practical guide to daily protein requirements for different goals.
Coming soonWhat Is BMR?
Basal Metabolic Rate explained — and why it is the foundation of any nutrition plan.
Coming soonStaying Hydrated Every Day
How much water you actually need and the best ways to hit your daily target.
Coming soonReady to get started?
Pick the calculator that matches your goal and get your personalised estimate in seconds — completely free.
Stay Updated
Receive new calculators, wellness tips, and health articles delivered to your inbox.
Optional. We respect your privacy.