Running, cycling, triathlon pacing, race prediction, and endurance nutrition calculators. Browse our free endurance & racing tools below — all calculators are instant, accurate, and require no sign-up.
Age-Graded Running Time Calculator — Calculate your age-graded running performance percentage. Compare times across ages and genders using WMA/USATF age-grading standards.
Aerodynamic Drag Calculator — Calculate aerodynamic drag force and power required to overcome air resistance. Input CdA, speed, and air density to estimate drag and power savings from position changes.
Carb Loading Planner Calculator — Plan your carbohydrate loading protocol with daily carb targets based on body weight. Supports classic 3-day and modified 1-day carb loading strategies for endurance events.
Boston Marathon Qualifying Pace Calculator — Calculate your Boston Marathon qualifying time and target pace by age and gender. Includes BQ buffer recommendations and mile-by-mile pacing strategy.
Cycling Drafting Benefit Calculator — Estimate power savings from drafting behind another cyclist. Calculate drag reduction by wheel gap, group size, and position in the peloton.
Cycling FTP Test Calculator — Calculate your Functional Threshold Power (FTP) from 20-minute, 8-minute, or ramp test results. Get Coggan power training zones and W/kg classification.
Lactate Threshold Pace Calculator — Calculate your lactate threshold pace and heart rate training zones from recent race times. Estimate LT pace for 10K, half marathon, and marathon distances.
Power-to-Weight Ratio Calculator — Calculate your cycling power-to-weight ratio (W/kg) and see where you rank from Cat 5 to World Tour pro. Compare climbing ability and race category.
Race Predictor (Riegel) Calculator — Predict race times at any distance using the Riegel formula. Estimate 5K, 10K, half marathon, and marathon times from a single recent race result.
Running Economy Calculator — Calculate your running economy (RE) as oxygen cost per kilometer. Compare your efficiency to elite benchmarks and track improvements with VO2 and pace inputs.
Sports Drink Formulation Calculator — Design your own sports drink with optimal carbohydrate concentration, sodium content, and osmolality. Calculate DIY sports drink recipes for training and racing.
Taper Week Planner Calculator — Plan your pre-race taper with a day-by-day schedule. Reduce training volume 40–60% over 1–3 weeks while maintaining intensity for peak race-day performance.
Triathlon Pacing Calculator — Calculate per-discipline pacing targets from a total triathlon finish time goal. Break down swim, bike, and run paces for Sprint, Olympic, 70.3, and Ironman.
Triathlon Transition Calculator — Calculate total triathlon time including swim, bike, run, T1, and T2 transitions. Plan splits for Sprint, Olympic, 70.3, and Ironman distances.
Ultra Marathon Nutrition Calculator — Calculate calorie, carbohydrate, sodium, and fluid needs for ultra marathon races. Plan nutrition by distance, pace, body weight, and conditions.
VO2max Sport Benchmark Calculator — Compare your VO2max to sport-specific benchmarks by age, gender, and competition level. See your percentile ranking and performance classification for running, cycling, and more.