About RunDida
Free running tools built by runners, for runners.
Our Mission
RunDida exists to give every runner free access to the training tools and race-day calculators that used to live only in coaching manuals and premium apps. Whether you are preparing for your first 5K or chasing a Boston qualifying time, our tools help you train smarter and race with confidence.
What We Offer
- Running Calculators — pace, splits, finish time, heart rate zones, VO2max, and more
- Marathon Countdown — the world's first emotionally intelligent countdown with 5 personality modes
- Marathon Profiles — course details, weather history, and pacing strategy for major races
- Training Guides — evidence-based articles on nutrition, tapering, and race-day planning
- Printable Outputs — pace bands and wall charts you can take to the start line
Our Methodology
Every calculator on RunDida is grounded in peer-reviewed sports science and established coaching frameworks. Read our full methodology page for detailed formula documentation, validation processes, and source citations.
- Pace and VDOT — based on Jack Daniels' Running Formula and VDOT tables
- Heart Rate Zones — calculated with the Karvonen method (% of heart rate reserve)
- VO2max Estimation — derived from the Cooper and Daniels regression models
- Race Prediction — uses Riegel's formula with distance-specific adjustments
- Calorie Estimation — based on MET research from the Compendium of Physical Activities
We cite our sources on every tool page so you can verify the science yourself.
Our Approach
- Privacy First — all calculations run in your browser. No data is sent to our servers.
- Mobile First — every tool is designed for phones first, then scaled up for desktop
- No Account Required — use any tool instantly with zero sign-up friction
- Always Free — no paywalls, no premium tiers
Contact
Have a question, found a bug, or want to suggest a new tool? Send us a message and we will get back to you.