The marathon training app for Garmin and COROS runners.
Pick a marathon goal — sub-3, sub-3:30, sub-4 — and SUB calculates your per-kilometre target pace, finds matching races, syncs your training automatically, and auto-completes coach-assigned workouts.
Free on iOS and Android.
For Garmin Runners
SUB supports the full Garmin lineup — Forerunner 165 / 265 / 965, Fenix 7 / 8, Epix Pro, and every other Connect-compatible model. After connecting Garmin Connect, the past 90 days of activities backfill automatically and every subsequent run syncs within minutes.
Coach-assigned workouts (sub-3 long runs, sub-3:30 intervals, sub-4 tempo) auto-complete the moment a matching run lands — no manual tap required. If you have outgrown Garmin Connect as a pure logging tool, SUB is the missing goal-driven training layer.
For COROS Runners
SUB supports COROS Pace 3, Apex 2 Pro, and Vertix 2. Activities sync automatically with full running dynamics — stride length, vertical oscillation, vertical ratio, ground contact time — and lap-by-lap detail.
Coach-assigned workouts auto-complete the moment COROS finishes its sync.
Use Both Garmin and COROS Together
Connect both watches to the same SUB account. When you wear both on the same run, SUB intelligently deduplicates: monthly and weekly mileage take the maximum across sources (never the sum), so totals stay honest.
Coach-assigned workouts auto-complete from whichever watch syncs first.
Train for the World Marathon Majors and beyond
SUB's race finder lists every major marathon worldwide. Pick your target race, SUB calculates the per-kilometre pace required for your goal time, and you can drop the race date into a coach-assigned training plan.
- Boston Marathon (April)
- London Marathon (April)
- Berlin Marathon (September)
- Chicago Marathon (October)
- New York City Marathon (November)
- Tokyo Marathon (March)
- Standard Chartered HK Marathon (Jan–Feb)
- Osaka Marathon (February)
- Sydney Marathon (August)
- Valencia Marathon (December)
Plus hundreds of qualifying and local races — see SUB's race finder for the full list.
Marathon Pacing Guide
- Sub-3 marathon: 4:15 / km (6:52 / mile) — elite goal
- Sub-3:30 marathon: 4:58 / km (8:00 / mile) — advanced goal
- Sub-4 marathon: 5:41 / km (9:09 / mile) — popular milestone
- Sub-5 marathon: 7:06 / km (11:25 / mile) — first marathon goal
Frequently Asked Questions
What is SUB?
SUB is a free marathon training app for Garmin, COROS, Apple Watch, and Polar runners. Pick a marathon goal (sub-3, sub-3:30, sub-4 or anywhere from sub-5 to sub-3), and SUB calculates the per-kilometre target pace, finds matching races, syncs your training automatically, and lets coach-assigned workouts auto-complete the moment your watch syncs.
What is the best app for Garmin marathon training?
SUB is the goal-driven marathon companion app for Garmin runners. Connect Garmin Connect once and every run auto-syncs to SUB. Pick a sub-3, sub-3:30, or sub-4 marathon goal and SUB calculates your target pace per kilometre. Coach-assigned workouts (long runs, intervals, tempo) auto-complete the moment a matching activity lands. Garmin Connect is a logging tool — SUB drives your training.
What is the best app for COROS Pace 3, Apex 2 Pro, or Vertix 2?
SUB supports every COROS watch including Pace 3, Apex 2 Pro, and Vertix 2. Activities sync automatically with full running dynamics — stride length, vertical oscillation, vertical ratio, ground contact time — and lap-by-lap detail. Coach-assigned workouts auto-complete within minutes of your run finishing.
How do I connect Garmin to SUB?
Open the SUB app on your phone, go to Settings → Connect Garmin, and link your Garmin account. The first sync backfills the past 90 days of activities (around 30 seconds). Every subsequent run auto-syncs within minutes. Free.
How do I connect COROS to SUB?
Open SUB, go to Settings → Connect COROS, and link your COROS account. First sync backfills 90 days of runs with full lap data and running dynamics. Subsequent runs sync every few hours.
Can I use Garmin and COROS at the same time?
Yes — and this is a core SUB feature. Connect both watches to the same SUB account. If you wear both on the same run, SUB intelligently deduplicates: monthly and weekly mileage take the maximum across sources (never the sum), so totals stay honest. Coach-assigned workouts auto-complete from whichever watch syncs first.
How is SUB different from Garmin Connect?
Garmin Connect logs your runs and shows historical analytics. SUB is goal-driven: pick a marathon goal (sub-3, sub-3:30, sub-4), get the target pace per kilometre, find matching races, store coach-assigned workouts, and let them auto-complete after your run. SUB also unifies COROS, Apple Watch, and Polar — perfect if you use multiple watch brands.
How to connect Garmin to SUB
- Open SUB: Open the SUB app on your phone.
- Settings → Connect Garmin: Go to Settings, then Connect Garmin.
- Connect: Connect your Garmin account.
- Wait for backfill: The first sync backfills the past 90 days of runs in about 30 seconds.
- Done: Every subsequent run auto-syncs within minutes. No plugin required.
How to connect COROS to SUB
- Open SUB: Open the SUB app on your phone.
- Settings → Connect COROS: Go to Settings, then Connect COROS.
- Connect: Connect your COROS account.
- Wait for backfill: The first sync backfills the past 90 days of runs with lap data and running dynamics.
- Done: Runs auto-sync every few hours from your COROS account.