About M42

M42 is a free marathon training coach. It builds your plan to race day, sets your paces from your actual fitness and uses your runs to show whether you're on track. The name is the distance: 42.195 km. The logo is an “M” drawn as a course profile: two climbs, then the finish.

What M42 does

• A periodised plan from your training start to race day: base, build, marathon-specific and taper.
• Personal paces and heart-rate zones that step up as your progress is confirmed.
• Import from Apple Health, Garmin, Strava, Polar, Oura, WHOOP, Fitbit and FIT/GPX/TCX files from any watch, with heart-rate, pace and elevation curves, running dynamics, resting heart rate and HRV.
• Progress at a glance: realistic race time, pace at the same heart rate, consistency and intensity mix.
• A treadmill mode with speed, incline and steps for every session, in English and German.

Built on research

The calculations follow published data and studies rather than gut feeling: paces from Jack Daniels' VDOT model, realistic marathon times from Vickers & Vertosick (2016), load progression that avoids big single-run jumps (Frandsen et al. 2025) and a three-week taper (Bosquet et al. 2007; Smyth & Lawlor 2021). Every assumption and source is listed in the methodology in the repository.

Your data stays yours

There's no account and no tracking. Everything you enter or import stays in the browser on your device. Details are in the privacy policy.

Open source

The source code is public on GitHub. Built with Next.js, React, TypeScript and Tailwind CSS. Bugs and ideas are welcome as issues in the repository.

Who's behind it

I'm Melvin Rinkleff, a platform engineer in Berlin. I built M42 to prepare for a marathon myself. More about me at rinkleff.dev and on GitHub.

Good to know

M42 doesn't replace medical or professional coaching advice. Listen to your body. M42 is not affiliated with Apple, Garmin, Strava, Polar, Oura, WHOOP, Google or any other provider named. See the imprint.