Runwise
Running calculators. Fast. Clean. Built for runners.
Train smarter with science-backed calculators for pace, heart rate zones, race prediction, VO2 max, and training paces. No account required.
Running Calculators
Running Training Fundamentals
Runwise calculators are built on established running science. Here's what you need to know to train smarter.
Training Pace Zones
Running at the right pace for each workout is crucial for building fitness. Easy runs develop aerobic base, tempo runs build lactate threshold, and interval training improves VO2 max. Most runners run their easy runs too fast, which limits their training progress.
Heart Rate Zones
Heart rate is an objective measure of training intensity. By training in specific HR zones, you ensure workouts match your intended purpose. Zone 2 (easy) builds aerobic capacity, while Zone 4–5 (hard) develops speed and power.
VO2 Max & Fitness Level
VO2 max (millilitres of oxygen per kilogram per minute) measures your aerobic fitness. It's the best single predictor of running performance and can be improved through consistent interval training and tempo work over weeks and months.
Race Prediction Science
Modern race prediction models use power laws to extrapolate performance across distances. The Riegel formula (used by Runwise) assumes performance consistency and lets you confidently predict marathon times from a 5K result.
Running Power Zones
Power, measured in watts, reflects effort directly rather than the outcome of that effort. Unlike pace, it doesn't slow on hills or into a headwind at constant effort. Stryd, Garmin, and Polar each calculate running power with their own proprietary model, so zone tables have to be device-specific rather than universal.
Scaling Training Load
Knowing your training paces only answers half the question: how much quality running at each pace suits your current mileage matters just as much. Jack Daniels' methodology scales each zone's session volume as a percentage of weekly mileage, so hard efforts stay proportional as your training load changes.
Common Running Mistakes
Runwise helps runners avoid these frequent pitfalls.
Running all easy runs too fast
Without pace targets, most runners run easy efforts too hard, which wastes recovery time and limits training adaptation. The Training Paces calculator gives you specific targets so your easy runs truly develop aerobic fitness without building fatigue.
Training at the wrong heart rate zones
Training intensity should match your goal. Without HR zone targets, you might do easy runs at tempo pace (wasting energy) or tempo runs at easy pace (not building fitness). The HR Zone Calculator ensures each workout drives the right adaptation.
Setting unrealistic race goals
Without a scientific prediction method, it's easy to aim too high (demoralizing) or too low (wasted potential). Race time predictors let you set realistic but ambitious targets based on current fitness, boosting motivation and pacing strategy.
Ignoring aerobic fitness data
VO2 max is the strongest predictor of running performance. Knowing yours lets you track progress, predict across all distances, and see how training investments pay off over time.
Trusting pace on hills and in the wind
Pace slows on hills and into a headwind even when effort stays constant, and heart rate lags behind sudden intensity changes. The Power Zones Calculator turns your device's watt output into training zones that stay consistent regardless of terrain or conditions.
Running the same quality volume every week
A fixed number of intervals or tempo minutes can be too much in a low-mileage week and too little in a high-mileage one. Workout Suggestions scales each zone's session volume to your actual weekly mileage, so quality work stays proportional as your training load changes.
How Runwise Helps
Eight free calculators to train smarter and race faster.
- → Convert paces between formats (min/km, min/mile, km/h) in one click
- → Predict race times across all distances using the Riegel formula
- → Calculate training paces using Jack Daniels' VDOT method
- → Find your heart rate zones using Max HR or lactate threshold methods
- → Estimate VO2 max from race performance and track fitness trends
- → Predict parkrun times with pacing splits and age grading
- → Get power training zones for Stryd, Garmin, and Polar
- → Generate workout suggestions scaled to your weekly mileage
Want to know who's behind Runwise and the methods behind the numbers? Read our About page