Training Calculators
Data-driven tools built from real training algorithms. The same calculations I use for my own marathon, Ironman, and HYROX preparation.
Race-Specific
Calculators designed for specific race formats
HYROX Pace Calculator
Division-Specific Pacing
Calculate running splits and station time targets for HYROX. Division-specific pacing with strength profile adjustments.
Try Calculator for FreeTriathlon Race Time Estimator
Estimate Sprint to Ironman finish times from your swim CSS, bike FTP, and easy run pace. Shows realistic best-to-conservative ranges.
Try Calculator for Free NewIronman Race TSS Planner
Reverse-calculate your target bike watts, run pace, and swim pace from a TSS budget. Science-backed pacing for 70.3 and full Ironman.
Try Calculator for FreePace & Prediction
Predict race times and calculate optimal pacing
VDOT Calculator
Calculate your VDOT from any race result. Get training paces for all 5 Daniels zones and predict equivalent race times.
Try Calculator for Free Coming SoonMarathon Pace Calculator
Calculate splits and pacing strategy for any distance from 5K to ultramarathon.
Coming Soon Coming SoonRace Time Predictor
Predict finish times using Riegel formula, VDOT, and CTL-adjusted methods.
Coming Soon Coming SoonBoston Cutoff Tracker
Track your BQ buffer, see cutoff projections, and get age-up predictions.
Coming SoonTraining Zones
Calculate your training zones for structured training
Training Zones Calculator
Calculate HR, pace, and power zones using Karvonen, %Max HR, or LTHR. Compare Strava vs Garmin vs TrainingPeaks.
Try Calculator for FreeHeart Rate Zones
Calculate HR zones from max heart rate or lactate threshold heart rate.
Try Calculator for Free Coming SoonMarathon HR Pacer
Heart rate-based marathon pacing with terrain and weather adjustments.
Coming SoonNutrition & Hydration
Science-based fueling and hydration tools for race day and training
Endurance Fueling Planner
Division-Specific Pacing
Plan your race nutrition: carbs, fluid, and sodium per hour with a 20-minute execution checklist. Brand-agnostic, based on IOC and ACSM guidelines.
Try Calculator for FreeSweat Rate Calculator
Calculate your sweat rate from pre/post-exercise weigh-ins. Get fluid deficit %, sweat classification, and replacement recommendations.
Try Calculator for FreeRace Day Nutrition Planner
Duration-tiered carb recommendations with sport-specific fluid targets. Includes gut training guidance and execution plan.
Try Calculator for FreeElectrolyte Calculator
Estimate sodium, potassium, and magnesium needs based on sweat rate and saltiness. Personalized electrolyte strategy.
Try Calculator for FreeGlycogen Depletion Calculator
Predict when you'll bonk: estimate glycogen stores, depletion time, and carb intake needed to extend performance.
Try Calculator for FreeReal Algorithms, Real Results
These calculators are ported from the training analysis system I built for my own marathon and Ironman preparation. They use the same algorithms used by professional coaches and sports scientists.