Race Time Predictor
How fast will you run GTC55?
GTC55 race stats pre-loaded (53.3 km, 3,500 m D+). Enter a known race result to get an elevation-adjusted finish time estimate.
53.3km3,500m D+Winner: ~5h29Cutoff: 18h
Full Gran Trail Courmayeur - GTC55 course data: aid stations, cutoffs, course profile
- ✓Your race (done)
- 2About you
- 3Your finish
1Your race
- The course
53.3 km, but it costs 106 km-effort. The 3,505 m of descent is where legs go.
2How should we estimate you?
Start with
Pick whichever you have. After your first estimate we ask for the other - two inputs give a firmer read.
Same as gain. Edit if different.
Hours, or h:mm
- TrailMath
Got a UTMB index? Hand it over, it's the straightest read I get. No index? A long, hilly past race works too.
3 · Your predicted finish
88 km-effort (ITRA, gain only)106 km-effort
Add a past race or your index to get a finish time.
GTC55 finish times by UTMB Index
Predicted finish on the GTC55 course (53.3 km, 3,500 m D+) for each UTMB Index, with the margin to the 18h00 cutoff.
| UTMB Index | Predicted finish | Average pace | Margin to cutoff |
|---|---|---|---|
| 850 | 5h38 | 6:20 /km10:12 /mi | +12h22 |
| 800 | 6h09 | 6:56 /km11:09 /mi | +11h51 |
| 750 | 6h44 | 7:35 /km12:12 /mi | +11h16 |
| 700competitive | 7h21 | 8:17 /km13:20 /mi | +10h39 |
| 650 | 8h03 | 9:03 /km14:34 /mi | +9h57 |
| 600 | 8h47 | 9:54 /km15:56 /mi | +9h13 |
| 550 | 9h37 | 10:49 /km17:24 /mi | +8h23 |
| 500mid-pack | 10h30 | 11:49 /km19:02 /mi | +7h30 |
| 450 | 11h29 | 12:55 /km20:48 /mi | +6h31 |
| 400back of the pack | 12h33 | 14:08 /km22:44 /mi | +5h27 |
| 350 | 13h43 | 15:27 /km24:51 /mi | +4h17 |
| 300 | 15h00 | 16:53 /km27:10 /mi | +3h00 |
The 18h00 cutoff sits at about Index 197. The typical winning time, 5h29, sits at about Index 866. At the 2026 edition, the median of the 456 finishers took 10h45, about Index 487. A model estimate, not an official ITRA or UTMB figure.
From a result you already have
What the predictor gives on GTC55 for a few common reference results.
| Road marathon | 3h00 → 9h15 | 3h30 → 10h47 | 4h00 → 12h20 | 4h30 → 13h52 |
|---|---|---|---|---|
| 50 km trail, 2,000 m D+ | 5h30 → 7h45 | 6h30 → 9h09 | 7h30 → 10h34 | 8h30 → 11h58 |
Road marathons use the tool's rougher power-law fallback.
To prepare each checkpoint, use the GTC55 aid station planner.
GTC55 course in numbers
- Climbing per kmClimbing per mile
- 66 m347 ft
- ITRA km-effort
- 88 (50K)
- Highest point
- 2,830 m9,285 ft
- Biggest climb
- +1,079 m over 5.9 km at 18.0%+3,540 ft over 3.7 mi at 18.0%
- Steepest climb
- +154 m over 0.4 km at 27.7%+505 ft over 0.2 mi at 27.7%
- Longest descent
- -1,322 m over 13.1 km at 9.2% (down to Courmayeur (Finish))-4,337 ft over 8.1 mi at 9.2% (down to Courmayeur (Finish))
- Track climbing above 3%
- 39%
- Winning time / cutoff
- 5h29 / 18h00 (3.3x the winner's time)
Section-by-section climbs, descents and grades are on the GTC55 course page.
Predict your GTC55 finish time from a reference race result, adjusted for the course's 53.3 km and roughly 3,500 m of elevation gain. The overall cutoff is 18h.
About Gran Trail Courmayeur - GTC55
Gran Trail Courmayeur - GTC55 covers 53.3 km with around 3,500 m of elevation gain, starting in Courmayeur, Valle d'Aosta, Italy. The overall cutoff is 18 hours.
Crew access is allowed at Youlaz (15.12 km), Mont Fortin (24.65 km), Lago Combal (36.1 km) and Rifugio Maison Vieille (44.66 km).
Checkpoint data approximate - verify against the current official race guide at gtcourmayeur.com before your race.
How the prediction works
Your result becomes a UTMB Index, mapped onto GTC55 by the calibrated model behind the ITRA / UTMB Index Estimator. Full methodology.
Build a training plan targeted at your GTC55 goal time
TrailMath uses these models to build periodized plans adjusted to your goals and terrain.
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