A pregnancy due date isn't a prediction of birth day — it's a 40-week estimate from your last period. Here's the real math behind Naegele's rule, ultrasound dating, and why the date moves.
VO2 max has become the wearable world's favorite longevity metric. Here's how it's actually calculated, why your watch's estimate can be off by 10 points, and a real worked example.
Zone 2 training is everywhere right now, but most people doing it aren't actually in zone 2. Here's the real heart rate math, a worked example, and how to calculate your own zones.
How many drinks put you over 0.08% BAC? See the Widmark formula worked out with real numbers, why weight and sex change the answer, and why no calculator can tell you it's safe to drive.
Your treadmill's 'Fat Burn' mode is misleading you. Learn how heart rate zones actually work, the Karvonen formula vs 220-minus-age, and how to train zones 1–5 for real results.
The 8-glasses-a-day rule isn't based on real science. Here's the actual formula for daily water needs — based on body weight, activity, and climate — plus how to calculate yours.
Most people pick their 16:8 fasting window by feel. Here's how to calculate your ideal eating window based on your sleep schedule, TDEE, and lifestyle — and why the difference matters.
Your weight tells you how much you carry. Your waist-to-hip ratio tells you where — and where matters for heart disease risk. Learn the WHO categories and how to measure correctly.
The '1 gram per pound' rule is everywhere — but the research says something different. Learn exactly how much protein you need based on your goal, weight, and activity level.
The problem isn't how long you sleep — it's when your alarm fires. Learn the 90-minute sleep cycle formula, how to calculate your perfect bedtime, and why timing changes everything.
BMI is the world's most-used health metric — but most people misread it. Learn how to calculate your BMI, what the ranges mean, and why it's only part of the picture.
Ideal weight isn't a single number — it's a range. Learn the four formulas doctors use, why BMI alone misses the mark, and what actually matters for health.