Free Health & Longevity Calculators.
Free, science-backed calculators to quantify and optimize your health. No account, no email, no paywall.
Each one is single-purpose and built on a metric that actually moves healthspan. Use them individually, or combine the outputs: your TDEE feeds your protein target, your Zone 2 zone feeds your VO2 trajectory, your caffeine cutoff feeds your sleep debt.
Featured.
Featured.
Four anchor tools. Pick one, get a number you can act on in under a minute.
Protein Intake Calculator
Find your optimal daily protein target based on your weight, goal, and activity level.
Zone 2 Heart Rate Calculator
Find your Zone 2 training range, the most powerful lever for metabolic health.
Biological Age Calculator
Estimate your body age from lifestyle markers and see how it compares to your calendar age.
GKI & Autophagy Calculator
Compute your Glucose-Ketone Index and locate your stage on the 72-hour autophagy timeline.
The full library.
The full library.
All 41 calculators, organized by what they measure.
Nutrition
6 toolsProtein Intake Calculator
Find your optimal daily protein target based on your weight, goal, and activity level.
TDEE & Calorie Calculator
Calculate your Total Daily Energy Expenditure and ideal calorie targets for any goal.
Intermittent Fasting Calculator
Plan your intermittent fasting schedule with precise eating and fasting windows (16:8, 18:6, 20:4, OMAD).
Water Fasting Calculator
Project weight loss over a multi-day water fast (24–120h+), with an honest split between real fat and the water/glycogen that returns when you eat again.
Breaking a Fast
Check your refeeding-syndrome risk against the NICE criteria before you eat again, and get a graded schedule scaled to how long you fasted.
Keto Electrolyte Calculator
Sodium, magnesium and potassium targets for keto adaptation and extended fasting, with a contraindication check before any potassium figure is shown.
Fitness
7 toolsZone 2 Heart Rate Calculator
Find your Zone 2 training range, the most powerful lever for metabolic health.
VO2 Max Estimator
Estimate your aerobic capacity from resting heart rate and see where you rank.
Centenarian Decathlon
Peter Attia's 10-task fitness battery from Outlive. The level you should pass at 80+ to enjoy your 90s.
Sit-to-Rise Test
Score the 10-point Brazilian sit-to-rise test and see the mortality hazard ratio from the Araújo cohort studies.
Grip Strength Percentile
See your age- and sex-adjusted grip strength percentile plus the all-cause mortality link from the Leong (Lancet) cohort.
HRV Percentile by Age
Enter your RMSSD to see how your heart rate variability ranks for your age band, and what actually moves it.
Strength Level Calculator
Rank your bench, squat, and deadlift (untrained to elite) for your bodyweight and sex, with a Wilks score that compares strength across weight classes.
Heart
6 toolsAHA PREVENT Risk Calculator
The 2024 race-free AHA standard. Estimate 10- and 30-year cardiovascular risk per the 2026 ACC/AHA guideline.
Metabolic Syndrome Checker
Check your five metabolic-syndrome criteria (waist, triglycerides, HDL, blood pressure, glucose) and see exactly which ones you cross. 3 of 5 = positive.
Remnant Cholesterol Calculator
The atherogenic cholesterol fraction your panel doesn't print: total minus HDL minus LDL. Predicts heart risk even when LDL is at goal.
Pulse Pressure Calculator
The gap between your systolic and diastolic numbers, a simple marker of arterial stiffness. Get pulse pressure and mean arterial pressure from one reading.
Cholesterol Ratio Calculator
Total-to-HDL, triglyceride-to-HDL, and LDL-to-HDL ratios from your lipid panel: often better predictors of heart risk than any single cholesterol number.
LDL Cholesterol Calculator
Calculate LDL from total cholesterol, HDL, and triglycerides using both the Friedewald and modern Sampson (NIH) equations, plus non-HDL-C and LDL/HDL ratio.
Body Metrics
2 toolsSleep
3 toolsSleep Debt Calculator
Calculate your accumulated sleep debt over the last 7 nights and how to recover.
Caffeine Half-Life Calculator
Plot your bloodstream caffeine decay curve and find your personal cutoff time for sleep.
CBT-I Sleep Efficiency Calculator
Log a 7-day sleep diary, compute efficiency, and get the clinical sleep-restriction adjustment.
Longevity
17 toolsBiological Age Calculator
Estimate your body age from lifestyle markers and see how it compares to your calendar age.
Longevity Score
Audit your lifestyle across 6 longevity pillars and get a 0–100 healthspan score.
Peptide Reconstitution Calculator
Convert vial mg, bacteriostatic water mL, and target μg dose into exact insulin syringe units.
GKI & Autophagy Calculator
Compute your Glucose-Ketone Index and locate your stage on the 72-hour autophagy timeline.
Sauna Dose Calculator
Score your weekly sauna habit against the Finnish KIHD cohort threshold for cardiovascular and all-cause mortality reduction.
HOMA-IR Calculator
Combine fasting glucose and fasting insulin into a HOMA-IR score: the earliest reversible warning of insulin resistance, years before glucose moves.
eGFR Calculator
Estimate kidney filtration from serum creatinine, age, and sex using the 2021 race-free CKD-EPI equation, with CKD stage.
Phenotypic Age Calculator
Turn 9 standard blood markers into your body's biological age with the validated Levine PhenoAge clock. See how many years younger or older your body is.
TyG Index Calculator
Estimate insulin resistance from fasting triglycerides and glucose: the insulin-free alternative to HOMA-IR, off any standard lipid panel.
FIB-4 Index Calculator
The first-line non-invasive screen for advanced liver fibrosis in fatty liver disease, calculated from age, AST, ALT, and platelets. No biopsy.
A1C Calculator
Convert average glucose to estimated A1C and back, using the ADA eAG formula. Turn CGM/meter numbers into an A1C, or read a lab A1C as everyday glucose.
Metabolic Age Calculator
Decode the "metabolic age" your smart scale reported, from your resting metabolic rate versus the average for your years. Add body fat for a real result.
Menopause Age Calculator
Estimate when you'll likely reach menopause from your family history and smoking status, the two factors that shift the timing most.
TRT Dosage Calculator
Convert a prescribed weekly testosterone dose into the exact injection volume and U-100 syringe units, from your vial concentration and injection frequency.
Levothyroxine Dose Calculator
Estimate a weight-based levothyroxine starting dose (~1.6 mcg/kg) and round it to a real tablet strength, a sanity-check for the dose your clinician titrates to TSH.
Longevity Lab Panel Builder
Build a personalized checklist of the 26 blood tests that predict healthspan: optimal ranges, costs, and the calculator that interprets each. Copy the list for your doctor.
Iron Deficiency Calculator
Estimate your total iron deficit in mg (the amount needed to correct anemia and refill stores) with the Ganzoni equation clinicians use to plan iron repletion.
How they stack.
How they stack.
The outputs feed each other. Three example chains.
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