Running calculators
Plan your race. Predict your time. Pick your goal.
A growing toolkit for runners and triathletes — no signup, no math, no fluff.
Pace calculator
Convert pace, finish time and distance for any race from 5K to ultra. Includes split times and predicted race times.
Open the calculatorRace time predictor
Type a recent race result and we predict your finish time at every standard distance — 5K, 10K, half marathon, marathon and beyond.
Open the predictorHYROX time calculator
Combine your 1km run pace with station times to predict your HYROX finish — Pro, Open, Men, Women.
Open the HYROX calculatorTriathlon time calculator
Predict your finish time at any triathlon distance from sprint to ironman, with swim, bike, run and transition splits.
Open the triathlon calculatorTreadmill pace converter
Turn treadmill speed and incline into min/mile, min/km and outdoor-flat-equivalent pace.
Open the treadmill calculatorMarathon pace planner
Pick a target finish time and split strategy. Get first/second-half splits and every-5K targets to print on your wrist.
Open the marathon plannerVDOT calculator
Convert a recent race result to your Daniels VDOT score and get easy/marathon/threshold/interval training paces.
Open VDOT calculatorHeart rate zone calculator
Compute your 5 training zones from max HR and resting HR. Works for running, cycling and triathlon.
Open HR zones calculatorGrade-adjusted pace
Convert hill-running pace to flat-equivalent effort. Built for trail runners and ultra athletes.
Open GAP calculatorFTP calculator
Estimate your FTP from a 20-minute test and get all 7 Coggan power zones. The cycling-training gold standard.
Open FTP calculatorSwim CSS calculator
Compute your Critical Swim Speed from a 400m + 200m test and get 5 training pace zones. Built for pool swimmers and triathletes.
Open swim CSS calculatorAge-grade calculator
Convert your race time to a WMA age-grade percentage. Compare your performance to world records adjusted for your age — built for masters runners.
Open age-grade calculatorRace-day fueling planner
Build your per-hour carbs, fluid and sodium plan for any race duration, weight and climate. Get gel and bottle counts you can pack the night before.
Open fueling plannerWatts → speed predictor
Plug in power, weight, gradient, surface and aero position. Get predicted speed, W/kg and split times over 40K and 100K — pure cycling physics.
Open watts → speedMarathon training plan generator
Type a target time, current weekly km and weeks to race. Get a personalized week-by-week table with long runs, quality sessions, cutbacks and a 3-week taper.
Open plan generatorEstimated heart rate zones
No max-HR test? Pick a formula (Tanaka, Fox/Haskell or Gulati for women), enter your age and get all 5 training zones in BPM.
Open estimated HR zonesVO₂max calculator
Plug in distance covered in a 12-minute Cooper run and get VO₂max in ml/kg/min, your fitness rating and the percentile you sit in for your age.
Open VO₂max calculatorSweat rate calculator
Weigh yourself before and after a workout and we compute fluid loss per hour, dehydration percent and a per-hour replacement target you can drink.
Open sweat rate calculator