Free Running Tools

Calculators I built for runners — no signup, no catch. Pick one.

Race Time Predictor

Predict your finish times from 5K to 100 miles off one recent race — plus your speed-vs-endurance profile and training paces.

Work out pace, time, or distance from any two — and get even-effort splits for race day.

Turn one race into your VDOT score and easy / marathon / threshold / interval / repetition paces.

Dial in carbs, fluid, and sodium per hour for your ultra, with an aid-station-by-aid-station plan.

These run on what you type in. Connect Strava and NavRun works from your real training instead.