Interactive Tools
Try the tools. Then see what they look like with your real data.
Interactive running tools and calculators to compute training paces, heart rate zones, race predictions, and age-graded performances.
FIT, GPX, TCX, KML Converter & GPS Viewer
Free online running file converter and GPS track viewer. Convert between FIT, GPX, TCX, KML, CSV, and GeoJSON formats, crop start/end points for privacy, and preview your routes on an interactive map.
GPX & FIT Track Comparator — Dual Route & GPS Drift Analyzer
Compare two FIT, GPX, or TCX running track files side-by-side. Analyze distance discrepancies, GPS drift, sampling interval differences, elevation variances, and view interactive synchronized route playback.
GPS Drift & Distance Accuracy Analyzer
Diagnose why your Garmin, Apple Watch, or COROS distance is inaccurate. Inspect raw 2D GPS points vs watch firmware sensor fusion, sampling rate, altimeter slopes, and pause drift.
Pace Calculator
Free online running pace calculator — instantly calculate your target pace, estimated finish time, or distance for 5K, 10K, half marathon, and marathon. Built into Apex Run.
VDOT & Training Pace Calculator (Jack Daniels Formula)
Calculate your Jack Daniels VDOT score instantly from a recent race time or target goal. Find your exact Easy, Long Run, Marathon, Threshold, Interval & Repetition paces.
Running Efficiency & Economy Calculator
Calculate your running efficiency formulas instantly. Assess your Vertical Ratio, Duty Factor, and Aerobic Efficiency Factor (EF) from your running watch metrics.
Weekly Mileage Ramp-Up & 10% Rule Calculator
Free online running mileage calculator — safely increase your weekly running volume using the 10% rule and structured deload recovery weeks to avoid overtraining and injury.
Running Cadence Metronome & Audio Generator (180 SPM Tool)
Free online running cadence metronome — set target SPM (100–220), choose sound tones, practice live, or download MP3/WAV tracks for Garmin & Apple Watch.
Running Pace & Speed Converter (min/km, min/mi, km/h, mph)
Free online running pace converter — convert between min/km, min/mile, km/h, and mph. Easily convert running pace to mph for treadmill workouts and race targets.
Marathon Pace Chart & Target Splits
Free marathon pace chart with 5-minute time increments, mile and km splits, target per-km/per-mile paces, 5K/10K/half marathon checkpoints for 2:30 to 5:00 marathon finish times.
Half Marathon Pace Chart & Target Splits
Free half marathon pace chart with 5-minute increments, 5K, 10K, 15K splits, per-km and per-mile target paces for finish goals from 1:15 to 2:30.
10K Pace Chart & Target Splits
Free 10K pace chart with 2.5K, 5K, 7.5K split times, target per-km/per-mile paces, and speed in km/h for finish goals from 35:00 to 70:00.
5K Pace Chart & Target Splits
Free 5K pace chart with 1K, 2.5K, 4K split times, target per-km/per-mile paces, and speed in km/h for finish goals from 15:00 to 35:00.
Race Predictor
Apex Run's race predictor automatically forecasts your 5K, 10K, half marathon, and marathon finish times using Riegel's Formula calibrated to your last 6 weeks of real training data — no manual input required.
Heart Rate Zones Calculator
Free online running heart rate zones calculator. Instantly calculate your 5 training zones using Max HR, Karvonen (HRR), or Lactate Threshold (LTHR) methods. Perfect for configuring custom zones in Apex Run.
WMA Age-Grading Calculator for Runners
Free online road running WMA age-grading calculator. Find your age-graded percentage score, prime-age equivalent finish time, and master runner level for 5K, 10K, Half Marathon, and Marathon.