Chiang Mai, Thailand · Saturday, October 3, 2026

Fixed Distance 100K

CNX 100K Ultra Marathon

2 days to go
100 km Distance
872 m Climbing
6.3 Grit · Hardcore
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18.7904° N, 98.9847° E © OpenFreeMap © OpenMapTiles Data from OpenStreetMap

What the course asks

Climbing rate 9 m / km Fast & Flat. This course is relatively flat and fast. Ideal for PB attempts.
Time limit 18 hours 10:48 min/km average. Generous. Walkable throughout for most of the field. About average for a 100K. Measured against 214 races of the same distance. Cut-off calculator →
Field size ~385 Large. Rarely out of sight of another runner.

DUV results for the 2025 edition (100km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

Typical conditions, October

Daytime high 26°C
Night low 19°C
Rainfall Showers likely
Daylight 11 h 57 m of light

Regional 2001-2020 average for October — NASA POWER, grid elevation 759 m. Not a forecast.

Results history

Year Race Finishers Men's winner Women's winner
2025 100km 385 Patthanapichai Trinwatthaworn · 08:33:21 Chunyarat Kongpol · 10:57:55
2024 100km 335 Patthanapichai Trinwatthaworn · 08:22:09 Waerohanee Waeyusoh · 09:18:29
2023 100km 345 Krittapas Pimukdech · 07:55:26 Nisachon Morgan · 09:58:17
2022 100km 207 Tanat Wijitsuntorn · 08:34:11 Nuntaporn Tengamnuay · 10:34:20

The field grew 15% between 2024 (335) and 2025 (385). 25% of the 2025 field were women.

DUV results for the 2025 edition (100km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

The Aid Station

Course-specific beta from the community

⛰️ terrain

This is a fast & flat course. Expect fast, runnable sections where rhythm is key.

By UltraHub Expert
👟 gear

With trail terrain, choose a shoe with moderate cushioning for optimal performance.

By UltraHub Expert
🥤 nutrition

For 100km+ efforts, prioritize real food at aid stations to prevent palate fatigue.

By UltraHub Expert

Gear for this race

Chosen for 100 km of trail with 872 m of ascent.

  • Trail Running Shoes 100 km of trail — cushioning that is still there in the last quarter.
  • Race Nutrition Past 100 km the palate quits before the legs do — carry more than one flavour.
  • Hydration Vests Flask capacity for 100 km, without the bounce.
  • Headlamps A 18 h limit puts you out there after dark.
  • Accessories Chafe and blisters end more 100 km races than fitness does.

La Sportiva

Prodigio Pro

RunRepeat found the La Sportiva Prodigio Pro to have a secure, locked-in fit due to its premium upper, and also praised the shoe's energetic ride, particularly…

$225 ★★★★★ 4.6

Asics

Trabuco Max 3

★★★★★ 4.6

Maurten

Gel 100

Hydrogel technology for 25g carbs per gel with minimal GI distress.

$3.5 ★★★★★ 4.7

Salomon

ADV Skin 12

Industry-standard 12L race vest with front flask pockets and minimal bounce.

$180 ★★★★★ 4.8

Nitecore

UT32

Dual-beam trail running headlamp (1100 lumens) with spot and flood beams.

$100 ★★★★★ 4.5

Darn Tough

Micro Crew Ultra Running

Merino wool trail running socks with lifetime warranty. Blister-resistant.

$23 ★★★★★ 4.7
All gear guides →

Overview

The CNX 100K Ultra Marathon, organised by Thailand Ultra, is a 100km road race held in Chiang Mai, Thailand, in October. With 872m of elevation gain over 100km, the course averages 8.7m of climb per kilometer.

This race's time limit of 18 hours translates to a 10.8 minutes per kilometer cutoff pace, which is tighter than 36% of 100km races. The most recent edition in 2025 saw 385 finishers, making it a larger event than 94% of its 315 peer 100km races.

Similar races

Other 100K trail ultras, closest in distance first.