Istria 100 - 21K 2027
The forecast arrives five days before the start.
Here you'll find the elevation profile, an estimated finish time based on your UTMB Index and details of the 2 aid stations to plan your nutrition and hydration segment by segment.
What's your time based on your UTMB?
Times estimated by the RAVIT model, learned from real ultra-trail finish times. Enter your UTMB Index (utmb.world) to get a personalized estimate.
Predicted race time based on your UTMB Index® · smoothed times achieved by runners at your level in past editions
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Cut-off times and crew - Istria 100 - 21K · 2027
Data from the official race rules, checked for every edition. The race rules prevail. Positions are interpolated along the GPX track and are a guide, not official course marking.
What you'll find at each aid station
| Product | BUJEkm 6.9 | UMAGkm 21.6 |
|---|---|---|
| Water | available | available |
| Hot meal | unavailable | available |
La feuille de ton assistance pour Istria 100 - 21K · 2027
L'assistance n'est autorisée sur aucun poste de cette course.
Elevation profile
The course and its aid stations
Istria 100 - 21K: times, aid-station stops and fuelling needs by UTMB® Index
Between a UTMB® Index of 500 and 800, the estimated finish time on this race runs from 1h53 to 1h16. These times include aid-station stops: they come from real durations between two timing points, and this race's timing does not measure stops separately.
Source| UTMB® Index | Estimated time | Night hours | Carbs | Fluid | Sodium | Cut-off margin |
|---|---|---|---|---|---|---|
| 500 | 1h53 | — | 113 g | 1.3 L | 942 mg | +2h07 |
| 550 | 1h44 | — | 104 g | 1.2 L | 867 mg | +2h16 |
| 600 | 1h34 | — | 94 g | 1.1 L | 783 mg | +2h26 |
| 650 | 1h30 | — | 90 g | 1.1 L | 750 mg | +2h30 |
| 700 | 1h26 | — | 86 g | 1 L | 717 mg | +2h34 |
| 750 | 1h22 | — | 82 g | 1 L | 683 mg | +2h38 |
| 800 | 1h16 | — | 76 g | 0.9 L | 633 mg | +2h44 |
Figures based on 60 g of carbohydrate, 700 mL of fluid and 500 mg of sodium per hour, "average" preparation and mild conditions (15–25 °C). Above 25 °C, count on roughly 900 mL/h and 700 mg/h. Carbohydrate intake is trained: 60 g/h is a floor, 90 g/h assumes a glucose-fructose blend and a gut used to it.
Measured on the 2026 edition: the field checkpoint by checkpoint
417 starters, 1.2% DNF rate, 2 timed checkpoints.
| Segment | km | Median | Middle half | Measured | Median passage | Still ranked |
|---|---|---|---|---|---|---|
| Groznjan → Buje | 6.9 | 44 min | 38 min – 49 min | 416 | 44 min | 416 |
| Buje → Umag | 21.7 | 1 h 39 | 1 h 24 – 1 h 53 | 412 | 2 h 23 | 412 |
“Median passage” is elapsed time from the start, not a clock time: the clock time depends on the edition.
Where runners drop out. Buje (4) · Groznjan (1) out of 5 total DNFs.
RAVIT record from the official timing of the 2026 edition, data from September 22, 2026.
SourceIn the 2027 ranking
Istria 100 - 21K is 22 km and 155 m of elevation gain, that's 23 km-effort: category XXS, among 95 races in 2027. Its time limit of 4 h requires a minimum speed of 5.4 km/h: rank 69 out of 88 of the widest cut-off times in XXS.
Short XXS trails 2027: less than 25 km-effort
Similar effort in 2027
- Val Maremola Trail ed.15 - Val Maremola Short Trail ed.11 · 23 km-effort
- Zugspitz Ultra Trail - Grainau Trail · 23 km-effort
- SWISS CANYON TRAIL - 16 KM · 22 km-effort
Other trails worth preparing for
Sources and method
- Time projection — times by UTMB Index are taken from the actual splits of runners in each level band on previous editions of this race, aid station stops included. No formula is used as long as these results exist.
- Trail nutrition — hourly targets for carbohydrate, fluid and sodium follow the commonly accepted ultra-endurance guidance. La Clinique du Coureur — Fuelling in trail running
- Course, aid stations and cut-offs — taken from the event's official rules, which prevail in case of any discrepancy. Official site — Istria 100 - 21K
Weather for Istria 100 - 21K
The weather for Istria 100 - 21K will appear here as soon as the forecast models reach that date, around five days before the start: feels-like temperature, rain, snow, wind and storms, section by section and at your passage time.
Detailed weather for Istria 100 - 21K, hour by hour on the courseFrequently asked questions
How many checkpoints?
Istria 100 - 21K has 2 checkpoints: 1 aid station and 1 water point. Details are in the two tables above.
What's the longest segment without aid?
The one leading to UMAG: 14.6 km and 109 m elevation gain. That's the one to load up for first.
How do I find the exact location of an aid station?
The Google Maps icon in the “Access” column opens the aid station's location: handy for planning your crew's routes.
What distance and elevation gain?
Istria 100 - 21K is 22 km long with 155 m of elevation gain.
How long to finish?
With a UTMB Index of 600 (average runner), the estimated time is around 1h34 for Istria 100 - 21K.
What's the weather forecast?
The weather for Istria 100 - 21K will be published on this page around five days before the start, once the forecast models reach the race date. It will be detailed section by section: feels-like temperature, rain, snow, wind and storms.
Want to stack the odds in your favor for Istria 100 - 21K?
In 2 minutes, RAVIT generates your complete plan: segment-by-segment time, carbs, water and sodium at every aid station, printable roadbook.
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