Training Tools
Physics-based calculators and planning tools for endurance athletes
Power to Speed
Convert power output to speed with aero and gradient factors
Power-Duration Curve
Estimate Critical Power, W′, and modeled FTP from your best efforts
CdA Estimator
Estimate your aerodynamic drag area from a steady cycling effort
Endurance Calorie Calculator
Daily calorie + macro targets for endurance athletes
Marathon Time Predictor
Predict marathon, half, 10K, 5K times — Riegel, with the Vickers-Vertosick marathon correction
VAM Calculator
Analyze climbing performance with VAM metrics and grade
Heart Rate Zones
Calculate training zones from max HR, LTHR, or HRR (Karvonen)
FTP Calculator
Estimate your FTP from a 20-min, 8-min, or ramp test
Running Pace Calculator
Daniels training paces (E/M/T/I/R) from threshold pace or a recent race
Carb-Per-Hour Fueling Calculator
Per-hour carbohydrate intake targets for endurance races
Taper Advisor
Generate a day-by-day taper plan for peak race readiness
Lactate Import
Import lactate test data to identify LT1 and LT2 thresholds
All calculators use physics-based models grounded in published research. Results are estimates — actual performance depends on individual fitness, conditions, and equipment. Pre-fills use your configured weight and CP from Settings.
Get the full picture
These calculators are a slice of what Gradescale does. Sign up free to track training load, fitness trends, and race readiness across every workout — no credit card required.