Istria 100 by UTMB - 42K

Istria 42K Finish Time Predictor

Istria 42K race stats pre-loaded (42 km, 1,000 m D+). Enter a known race result to get an elevation-adjusted finish time estimate.

42km1,000m D+Winner: ~2h51Cutoff: 8h

Full Istria 100 by UTMB - 42K course data: aid stations, cutoffs, course profile

1. Your race

Istria 42K

42 km · 1000 m D+ · 1153 m D-

Different race?

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

2. How should we estimate you?

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.

Distance (km)

Elevation gain (m)

Elevation loss (m)

Same as gain. Edit if different.

Finish time

Hours, or h:mm

3. Your predicted finish

52.0 km-effort (ITRA, gain only)57.8 km-effort

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

Istria 42K finish times by UTMB Index

Predicted finish on the Istria 42K course (42.0 km, 1,000 m D+) for each UTMB Index, with the margin to the 8h00 cutoff.

Istria 42K: predicted finish time by UTMB Index
UTMB Index	Predicted finish	Average pace	Margin to cutoff
850	2h38	3:46 /km	+5h22
800	2h53	4:07 /km	+5h07
750	3h09	4:30 /km	+4h51
700competitive	3h27	4:56 /km	+4h33
650	3h46	5:23 /km	+4h14
600	4h07	5:53 /km	+3h53
550	4h30	6:26 /km	+3h30
500mid-pack	4h55	7:02 /km	+3h05
450	5h23	7:41 /km	+2h37
400back of the pack	5h53	8:24 /km	+2h07
350	6h26	9:11 /km	+1h34
300	7h02	10:03 /km	+0h58

The 8h00 cutoff sits at about Index 227. The typical winning time, 2h51, sits at about Index 808. At the 2026 edition, the median of the 644 finishers took 5h44, about Index 415. A model estimate, not an official ITRA or UTMB figure.

From a result you already have

What the predictor gives on Istria 42K for a few common reference results.

Istria 42K: predicted finish from reference results
Road marathon	3h00 → 4h24	3h30 → 5h09	4h00 → 5h53	4h30 → 6h37
50 km trail, 2,000 m D+	5h30 → 3h38	6h30 → 4h18	7h30 → 4h57	8h30 → 5h37

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

Istria 42K course in numbers

Climbing per km: 24 m
ITRA km-effort: 52 (50K)
Highest point: 380 m
Biggest climb: +376 m over 3.6 km at 10.1% (through Livade)
Steepest climb: +112 m over 1.0 km at 11.2% (from Start - Motovun)
Longest descent: -98 m over 8.3 km at 1.0% (down to Umag (Finish))
Track climbing above 3%: 21%
Winning time / cutoff: 2h51 / 8h00 (2.8x the winner's time)

Section-by-section climbs, descents and grades are on the Istria 42K course page.

Predict your Istria 42K finish time from a reference race result, adjusted for the course's 42 km and roughly 1,000 m of elevation gain. The overall cutoff is 8h.

About Istria 100 by UTMB - 42K

Istria 100 by UTMB - 42K covers 42 km with around 1,000 m of elevation gain, starting in Motovun, Croatia. The overall cutoff is 8 hours.

Checkpoint data approximate - verify against the current official race guide at istria.utmb.world before your race.

How the prediction works

Your result becomes a UTMB Index, mapped onto Istria 42K by the calibrated model behind the ITRA / UTMB Index Estimator. Full methodology.

Build a training plan targeted at your Istria 42K goal time

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

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