The scale can’t tell the difference between fat and muscle — body fat percentage can. It’s a more useful picture of your body composition than weight or BMI alone, and you can estimate it with nothing but a tape measure. This calculator offers two validated, no-caliper methods: the U.S. Navy circumference method and Relative Fat […]
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Caffeine wears off slower than it feels like it does. Long after the alertness fades, a meaningful amount can still be circulating — quietly cutting into the deep sleep you can’t consciously feel it stealing. This calculator logs what you drank and when, then shows how much caffeine is still in your system at bedtime, […]
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Your body has its own clock — and it doesn’t always agree with your alarm. Some people are wired to rise early and fade by evening; others don’t hit their stride until later and would happily sleep in. That internal timing is your chronotype, and the gap between it and your work schedule is your […]
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Before you change how you eat, it helps to know two numbers: how much energy your body burns at rest (your BMR) and how much you burn across a full day (your TDEE, or maintenance calories). This calculator estimates both with the Mifflin-St Jeor equation — the formula dietitians and researchers reach for most often […]
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How old is your body — really? Your fitness age answers that. It compares your VO₂max (the volume of oxygen your body can use at peak effort) to population norms and tells you the age at which your fitness would be considered average. A 48-year-old with strong cardio fitness can carry the fitness age of […]
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Free testosterone is the small, unbound fraction of your total testosterone that is actually available for your body to use — and it often tells a more useful story than total testosterone alone. This free testosterone calculator gives you two tools in one. The Free Testosterone tab estimates your bioavailable and free testosterone from a […]
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