Free Tools
Healthspan Calculators
These free calculators give you a quick read on each of the four healthspan pillars: cardiorespiratory fitness (VO2 max), strength (grip), body composition (waist-to-height) and stability (sitting-rising), plus fitness age, fat loss, protein and runner tools. Each is a fast estimate; the full measured version across all four pillars on one scale is the complimentary Healthspan Audit.
Eleven free, evidence-based calculators: one for each pillar of healthspan, an overall read, a GLP-1 muscle-loss calculator, a fat loss timeline calculator, two tools for runners, and nutrition and body-composition tools. Each one gives you a quick estimate and what it means. They are estimates, not measurements: the full version, measured properly across all four pillars on the same scale we use in studio, is the free Healthspan Audit.
Run a health, fitness, or wellness site? Embed any of these calculators for free with one line of code.
The four pillars
Cardiorespiratory
VO2 Max Calculator
See your VO2 max percentile for your age and sex, or estimate it from your resting heart rate.
Open calculatorStrength
Grip Strength Test
Check your handgrip against the AWGS sarcopenia threshold, one of the best simple predictors of healthy ageing.
Open calculatorBody Composition
Waist-to-Height Ratio
A better signal than weight or BMI. The target is simple: keep your waist under half your height.
Open calculatorStability
Sitting-Rising Test
A no-equipment floor test scored out of 10, linked to all-cause mortality in published research.
Open calculatorFor runners
Running
Running Pace Calculator
Enter one race and predict your 5K, 10K, half and full marathon times, plus your pace per kilometre.
Open calculatorRunning
Heart Rate Zones Calculator
Your five training zones in bpm from your age, with the Karvonen method if you add your resting heart rate.
Open calculatorNutrition & body composition
Body Composition
Fat Loss Calculator
How long to reach your goal, honestly: a timeline in weeks, how much of the loss is actually fat, and your daily targets.
Open calculatorNutrition
Protein Intake Calculator
Your daily protein target in grams: a floor to hit every day and a higher target if you train to build or keep muscle.
Open calculatorBody Composition
Body Fat Percentage Calculator
Estimate your body fat with a tape measure using the US Navy method, against the healthy range for your age and sex.
Open calculatorWant the real thing, not an estimate?
The Catalyst Healthspan Audit scores all four pillars on a single 0 to 10 scale in two minutes, the same framework we use in studio. It is the front door to the 4-Pillar Healthspan Assessment.
Take the free Healthspan Audit
