Wellness

Learn the pace formula runners use to convert between min/km and min/mile, plus a full reference table converting pace to finish times for 5K, 10K, half marathon, and marathon distances.

Understand the Widmark formula used to estimate blood alcohol content, the factors that affect accuracy, legal BAC limits by country, and why BAC calculators are estimates rather than legal proof.

Evidence-based hydration guide explaining daily fluid requirements. Learn body weight fluid formulas, climate and exercise sweat-loss adjustments, and fluid balance science.

Science-backed guide to sleep architecture and ultradian sleep cycles. Learn NREM and REM stages, bedtime calculation math, individual sleep variations, and how to minimize sleep inertia.

Your maximum heart rate determines your five training zones — from fat-burning to peak performance. The old 220-minus-age formula is outdated. Here is the more accurate Tanaka formula, a zone table for every age, and how to use each zone.

The BMI scale classifies weight from underweight to obese — but what counts as healthy varies by age and sex. This guide explains the WHO chart, what your number actually means, and the well-documented limitations of BMI as a health measure.