Health & Fitness calculators

Choose a task below. Check each calculator’s assumptions and units before using its result.

Free Bicycle Chain Length Calculator

Determine exact chain link count from chainstay length and drivetrain cog sizes to prevent rear derailleur rip-off and chain slap.

Calculate gear inches, development, and speed at cadence for road and gravel setups.

Calculate body fat percentage, lean tissue weight, and fat mass using the official Department of Defense circumference tape measurement method.

Calculate your true 1RM maximum lift weight across Brzycki and Epley equations with full percentage rep ranges for powerlifting programming.

Calculate required pace per mile and kilometer to hit target finish times across 5K, 10K, Half Marathon, and Marathon race distances.

Calculate Basal Metabolic Rate (BMR), maintenance calories (TDEE), target calorie goals, and macro grams of protein, carbs, and fats.

Calculate maximal oxygen uptake ($VO_2$ max in mL/kg/min) and evaluate aerobic endurance fitness percentiles using the Cooper 12-Minute Test.