Eight useful tools to get started.
Check your body mass index from height and weight in seconds.
Estimate body fat percentage using the U.S. Navy tape method.
Estimate your maximum lift from any working set of reps.
Find your daily calorie needs for cut, maintain, or bulk goals.
Get your daily protein target based on weight and training.
Split your calories into protein, carbs, and fats with precision.
Daily hydration target adjusted for activity and climate.
See how your lifts compare to other athletes at your bodyweight.
Track strength, body composition, and physical benchmarks.
Check your body mass index from height and weight in seconds.
Calculate Basal Metabolic Rate to find baseline resting calories.
Calculate Total Daily Energy Expenditure based on your activity.
Estimate body fat percentage using the U.S. Navy tape method.
Check central fat distribution and cardiometabolic risk from waist and height.
Measure abdominal fat distribution and health risk using waist and hip size.
Check waist measurements against common risk thresholds.
Estimate body surface area for clinical dosing and physiologic comparisons.
Classify blood pressure readings using current clinical categories.
Estimate calories burned at rest using RMR-focused formulas.
Calculate how much of your weight is pure lean tissue.
Estimate your healthy weight range using Devine, Robinson, and Hamwi formulas.
Estimate your maximum lift from any working set of reps.
Forecast your next personal record from recent training data.
See how your lifts compare to other athletes at your bodyweight.
Calculate total and weekly volume from sets, reps, and weight.
Generate custom progression targets to keep getting stronger.
Measure fat-free mass index to track real muscle progress.
Your natural muscular ceiling based on frame and height.
Estimate your annual and monthly natural muscle gain rate.
Compare your lift standards to averages in the lifting community.
Compare your biological vs. fitness age from key markers.
Score lifestyle inputs against research-backed longevity markers.
Estimate how long until visible abs at your current rate.
Dial in calories, protein, and macros for your goal.
Find your daily calorie needs for cut, maintain, or bulk goals.
Estimate maintenance calories and plan a controlled reverse diet.
Plan a controlled calorie surplus for lean muscle gain.
Plan a sustainable deficit for your weight-loss timeline.
Get your daily protein target based on weight and training.
Split your calories into protein, carbs, and fats with precision.
Daily hydration target adjusted for activity and climate.
Set a water target from bodyweight, training load, and climate.
Optimize protein timing and portion size across meals.
Optimal loading and maintenance doses based on bodyweight.
Visualize cheat meal calories in terms of exercise equivalents.
Train hard, recover smart, avoid burnout and injury.
Predict recovery time between training sessions per muscle group.
Estimate next-day soreness from intensity, volume, and novelty.
Spot early signs of overreaching before it costs you progress.
Get the right deload week based on your last training block.
Score how well your sleep supports recovery and training adaptation.
Estimate accumulated sleep debt and catch-up time.
Build a weekly training split based on your days available.
Pace, splits, and calorie burn for running and swimming.
Convert pace, distance, and time for any run or race.
Find your exercise heart-rate zones from age and resting pulse.
Estimate recovery score and VO2 max from heart rate response.
Burn rate for walking based on distance, speed, and weight.
Energy burn for every stroke style and intensity level.
Calculate splits and pace per 100m for pool and open water.
Estimate future swimming speed and times based on frequency.
Plan muscle growth, fat loss targets, and body transformations.
Plan simultaneous fat loss and muscle gain over weeks.
Estimate weeks to reach your target waist size safely.
Estimate how long it will take to hit your target body fat percentage.
Reverse-engineer your plan from a target date to today.
The signature calculators you won't find on every generic fitness site.
Forecast your next personal record from recent training data.
Your natural muscular ceiling based on frame and height.
Compare your biological vs. fitness age from key markers.
Estimate how long until visible abs at your current rate.
Fresh tools added to the lab.
Check central fat distribution and cardiometabolic risk from waist and height.
Measure abdominal fat distribution and health risk using waist and hip size.
Check waist measurements against common risk thresholds.
Estimate body surface area for clinical dosing and physiologic comparisons.
Classify blood pressure readings using current clinical categories.
Estimate calories burned at rest using RMR-focused formulas.
Score lifestyle inputs against research-backed longevity markers.
Estimate maintenance calories and plan a controlled reverse diet.
Plan a controlled calorie surplus for lean muscle gain.
Set a water target from bodyweight, training load, and climate.
Score how well your sleep supports recovery and training adaptation.
Estimate accumulated sleep debt and catch-up time.
Build a weekly training split based on your days available.
Find your exercise heart-rate zones from age and resting pulse.
Estimate recovery score and VO2 max from heart rate response.
Plan simultaneous fat loss and muscle gain over weeks.
Estimate weeks to reach your target waist size safely.
Estimate how long it will take to hit your target body fat percentage.
Reverse-engineer your plan from a target date to today.
Educational guides paired with our calculators, with methods and practical examples.
Recovery The neurobiology and endocrinology of sleep debt: growth hormone secretion pulses, cortisol elevation, insulin sensitivity decline, and evidence-based sleep recovery protocols.
Nutrition A complete physiological blueprint for reversing out of a calorie deficit: restoring leptin, reviving thyroid hormones, lifting NEAT, and stabilizing maintenance intake.
Fitness Why the waist-to-height ratio (WHtR 0.5 rule) is replacing standard BMI in modern medicine for detecting ectopic visceral fat, cardiovascular risk, and metabolic syndrome.
Nutrition An evidence-based audit of creatine monohydrate: kidney function myths, hair loss studies, cellular hydration, and loading protocols.
Cardio The exercise physiology of VO2 max, cardiac output, Karvonen heart rate zones, Zone 2 mitochondrial biogenesis, and aerobic longevity.
Fitness A comprehensive exercise physiology guide on mechanical tension, effective sets, rep ranges, proximity to failure, and muscle growth.
A common journey through our tools — from baseline to goal.
Start with the calculator that matches your question. Each tool includes inputs, a formula, and a worked example. A pace conversion is arithmetic; a calorie target or body-fat timeline depends on assumptions about your body and activity.
Check measurements and units, read the limitations, and compare estimates with your actual progress. Our tools and AI-assisted guides have not been independently medically reviewed.
How we build these toolsEvery tool on HealthFitTools — one click away.
Practical answers about estimates, units, sharing, and our content process.
Yes. You can use the calculators without an account. The site uses analytics and may display advertising.
Accuracy depends on the formula and your inputs. Mathematical conversions differ from physiological estimates. Planning timelines and recovery scores use simplifying assumptions and do not guarantee outcomes.
Tools with unit-dependent inputs offer a metric and imperial switch. Check the unit label beside each field before entering a measurement.
Calculator pages include print and share controls. A shared result link includes the values you entered, so share it only when you are comfortable disclosing those values.
HealthFitTools publishes the guides with AI assistance. They have not been independently medically reviewed. Read our About page for the content process and limitations.
Free tools with visible formulas and practical limitations.
HealthFitTools is an open, evidence-based library of fitness and nutrition calculators, built for trainees, coaches, runners, and swimmers who want useful estimates without paywalls or forced registrations.
Whether your objective is reversing out of a prolonged calorie deficit, calculating your cardiovascular heart rate reserve bounds, estimating 1-rep maximums for a peaking block, or tracking visceral adiposity with the waist-to-height ratio, our tools combine established equations with simplified planning models.
Our fitness tools integrate the Mifflin-St Jeor, Katch-McArdle, U.S. Navy circumference, Karvonen, Epley, and Brzycki models. Every tool is independently mobile-responsive, unit-convertible (metric and imperial), and includes its calculation method.
Transparent methods and limitations
HealthFitTools publishes AI-assisted educational guides. We do not currently have independent medical reviewers. Established equations and simplified planning models are explained on each tool page.
Read our methodology