Waterproof Ratings: What 10K, 20K, and 30K actually mean

You check the forecast.  “A few showers.” So you pack a rain jacket, just in case, and tell yourself it’ll probably blow through. 

Then you’re on the trail. The wind picks up. Rain comes in sideways. 

Rain often doesn’t arrive neatly or follow a timetable. It mixes with wind, movement and the kind of conditions that test your gear fast.

Which is why waterproof ratings matter. Not as technical jargon, but as a practical way to understand how your gear will perform when the weather decides to stop cooperating. 

 What a waterproof rating actually measures 

A waterproof rating is a lab tested measure of how much water pressure a fabric can withstand before moisture starts to push through. The higher the number, the greater the resistance.  

 More specifically:  

• 10,000mm (10K) – Light rain, short exposure, low wind
• 20,000mm (20K) – Prolonged rain, wind, and pack pressure
• 30,000mm+ – Highly specialised or extreme alpine conditions 

Why 20K is the sweet spot  

XT Series Rain Jacket is rated to 20,000mm, double the 10,000mm standard found on many rain jackets. That gap matters more than it sounds. 

A 10K jacket in a New Zealand downpour, with wind and a pack on your back, puts a lot of stress on the garment. 

At 20K, you have the coverage to handle conditions that shift without warning: a clear morning that turns by midday, a ridge that catches crosswind, a track that keeps you out longer than planned. 

XT Series Rain Jacket also has a breathability rating of over 30,000g/m²/24hr, which allows heat and moisture to escape as you move, helping you stay comfortable on the uphill, not clammy under your jacket.  

Waterproof is also about how its built 

A rating tells you what a fabric can handle. Construction determines how it performs in the real world. XT rain jacket and pants are built with three‑layer recycled Cordura ripstop nylon,  

Fully seam‑sealed, windproof throughout 

Lightweight packability when rain clears 

Explore XT Rainwear