Race Time Predictor

How fast will you run GTC100?

GTC100 race stats pre-loaded (103 km, 7,400 m D+). Enter a known race result to get an elevation-adjusted finish time estimate.

103km7,400m D+Winner: ~15h20Cutoff: 33h

Full Gran Trail Courmayeur - GTC100 course data: aid stations, cutoffs, course profile

103 kmdistance7,400 mD+7,405 mD-214km-effort

GentleSteadySteepVery steep

Your race (done)
About you
Your finish

1Your race

GTC100Official course loaded · 103 km · 7,400 m D+Different race?

Have the GPX? Measure the exact course in the GPX Explorer

The course
103 km, but it costs 214 km-effort. The 7,405 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.

Distance (km)

Elevation gain (m)

Elevation loss (m)

Same as gain. Edit if different.

Finish time

Hours, or h:mm

From my Strava historyYour last 90 days of real training. Opens the TrailMath app.Read-only access to your activities. Nothing is posted to Strava, and no training plan is created until you ask for one.

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

177 km-effort (ITRA, gain only)214 km-effort

Add a past race or your index to get a finish time.

GTC100 finish times by UTMB Index

Predicted finish on the GTC100 course (103.0 km, 7,400 m D+) for each UTMB Index, with the margin to the 33h00 cutoff.

GTC100: predicted finish time by UTMB Index
UTMB Index	Predicted finish	Average pace	Margin to cutoff
850	13h21	7:46 /km12:31 /mi	+19h39
800	14h35	8:30 /km13:41 /mi	+18h25
750	15h57	9:17 /km14:57 /mi	+17h03
700competitive	17h26	10:09 /km16:21 /mi	+15h34
650	19h03	11:06 /km17:52 /mi	+13h57
600	20h50	12:08 /km19:32 /mi	+12h10
550	22h46	13:16 /km21:21 /mi	+10h14
500mid-pack	24h53	14:30 /km23:20 /mi	+8h07
450	27h12	15:51 /km25:30 /mi	+5h48
400back of the pack	29h44	17:19 /km27:53 /mi	+3h16
350	32h30	18:56 /km30:28 /mi	+0h30
300	35h32	20:42 /km33:19 /mi	2h32 past the cutoff

The 33h00 cutoff sits at about Index 342. The typical winning time, 15h20, sits at about Index 772. At the 2026 edition, the median of the 425 finishers took 25h00, about Index 497. A model estimate, not an official ITRA or UTMB figure.

From a result you already have

What the predictor gives on GTC100 for a few common reference results.

GTC100: predicted finish from reference results
Road marathon	3h00 → 21h55	3h30 → 25h34	4h00 → 29h13	4h30 → 32h52
50 km trail, 2,000 m D+	5h30 → 18h21	6h30 → 21h42	7h30 → 25h01	8h30 → 28h20

Road marathons use the tool's rougher power-law fallback.

To prepare each checkpoint, use the GTC100 aid station planner.

GTC100 course in numbers

Climbing per kmClimbing per mile: 72 m379 ft
ITRA km-effort: 177 (100M)
Highest point: 2,830 m9,285 ft
Biggest climb: +1,507 m over 11.6 km at 12.1% (through Youlaz)+4,944 ft over 7.2 mi at 12.1% (through Youlaz)
Steepest climb: +810 m over 3.3 km at 23.6% (Brenva to Skyway Pavillon du Mont Fréty (life base))+2,657 ft over 2.1 mi at 23.6% (Brenva to Skyway Pavillon du Mont Fréty (life base))
Longest descent: -1,198 m over 10.5 km at 10.1% (through La Thuile)-3,930 ft over 6.5 mi at 10.1% (through La Thuile)
Track climbing above 3%: 44%
Winning time / cutoff: 15h20 / 33h00 (2.2x the winner's time)

Section-by-section climbs, descents and grades are on the GTC100 course page.

Predict your GTC100 finish time from a reference race result, adjusted for the course's 103 km and roughly 7,400 m of elevation gain. The overall cutoff is 33h.

About Gran Trail Courmayeur - GTC100

Gran Trail Courmayeur - GTC100 covers 103 km with around 7,400 m of elevation gain, starting in Courmayeur, Valle d'Aosta, Italy. The overall cutoff is 33 hours.

Crew access is allowed at Arpy (12.67 km), Rifugio Deffeyes (24.78 km), La Thuile (34.18 km), Youlaz (40.42 km), Mont Fortin (49.95 km), Lago Combal (61.4 km), Rifugio Maison Vieille (70.06 km), Skyway Pavillon du Mont Fréty (life base) (78.02 km), Rifugio Bonatti (89.87 km) and Currù (97.26 km). Drop bags are available at Skyway Pavillon du Mont Fréty (life base).

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 GTC100 by the calibrated model behind the ITRA / UTMB Index Estimator. Full methodology.

Build a training plan targeted at your GTC100 goal time

TrailMath uses these models to build periodized plans adjusted to your goals and terrain.

Build my plan