About TrainingZones.io
Free, science-based training tools for endurance athletes.
Why TrainingZones.io exists
Heart rate zones, FTP, CSS, VMA. These tools transform training, but they're often hidden behind paywalls or buried in coaching manuals. We built TrainingZones.io to make them free, simple, and accurate for every athlete, from absolute beginners to seasoned triathletes.
Our approach
Every calculator on this site is built on peer-reviewed research (Tanaka, Karvonen, Daniels, Coggan, and others). We cite our sources, explain our formulas, and never hide behind black-box predictions. If a calculator gives you a number, you can see exactly how it got there.
Who we are
TrainingZones.io is a solo project. I'm a passionate amateur triathlete and runner who spent years frustrated by scattered, expensive, or overcomplicated training tools. I'm not a certified coach, and I say so openly. What I bring is a deep love for the sport, respect for the science, and a software-engineering mindset focused on clarity and trust.
What we offer today
- •30+ free training calculators (running, cycling, swimming, triathlon)
- •Educational guides with FAQs and scientific references
- •Available in 6 languages (English, French, German, Italian, Spanish, Portuguese)
Get in touch
Have a question, found a bug, or want to share feedback? We read every message.