Which pack or vest for trail and ultra running?
Written by Victor Michel — history enthusiast and passionate alpinist based in Chamonix. Published August 1, 2026
The trail pack or vest is worn for the entire event on semi-autonomous races: it must hold the entirety of the mandatory gear without hindering your stride. Volume is chosen by distance, not by fashion.
What volume for what format?
A short format (under 30 km) generally needs only 5 to 8 L: water, windbreaker, phone. A 90 km+ ultra requires 10 to 15 L to fit the entirety of the mandatory gear (waterproof jacket, over-trousers, survival blanket, lights, food reserve) without over-compressing the load.
Flasks or a water reservoir?
Soft flasks in front pockets (500 to 600 ml each) remain the benchmark for hydration accessible without stopping. A water reservoir in the back compartment usefully supplements this on long stretches without aid stations, particularly during Heat Kits, when the minimum reserve rises to 2 L — see the UTMB mandatory-gear breakdown.
| Criterion | Recommendation | Why |
|---|---|---|
| Volume | 5 to 8 L for a short format, 10 to 15 L for a 90 km+ ultra | Must hold all the mandatory gear without being oversized |
| Front flasks | At least 2 slots, 500 to 600 ml each | Hydration accessible without stopping |
| Back pocket | Compatible with a 1.5 to 2 L soft reservoir | Extra water reserve on long stretches without aid stations |
| Accessible pockets | At least 2 zipped front pockets for gels and phone | Refuelling without removing the vest |
| Compression | Adjustable side elastics | Stable load, no bouncing on technical descents |
Editorial selection
Top 5 recommended packs and vests for trail and ultra running
Five references covering short formats as well as multi-day ultras.
Salomon — ADV Skin
The historic benchmark trail vest, stable carry, very wide choice of volumes (5 to 12 L).
Raidlight — Revolutiv
French brand specialising in ultra-distance, bounce-free carry system designed with elite athletes.
Ultimate Direction — Mountain Vest
American pioneer of the trail vest, numerous pockets accessible on the move.
Nathan — VaporAir
Good back ventilation, adjustable compression, geared toward long formats.
Ferrino — X-Run
Italian brand, good value for a first trail vest.
Independent editorial selection, with no commercial link or partnership.
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FAQ
Backpack or trail vest: what's the difference?
A trail vest hugs the torso with front pockets accessible without removing it, unlike a classic backpack. It's the benchmark for running, where quick access matters more than volume.
What minimum volume for carrying the UTMB mandatory gear?
10 to 15 L generally suffices to fit a waterproof jacket, over-trousers, survival blanket, headlamps and food reserve for an ultra format without over-compressing.
How many flasks do you need in front pockets?
Two slots of 500 to 600 ml each are the standard on nearly all current trail vests.
Is the pack or vest mandatory for the entire event?
Yes, on semi-autonomous races it must be worn from start to finish with the entirety of the mandatory gear, checkable at any time by race officials.
What empty weight for a trail vest?
150 to 300 g empty depending on volume and carry system, excluding flasks and mandatory gear.