07/10/2026
Ever looked at a waterproof jacket and thought… what does 10K/10K actually mean?
Hydrostatic head, breathability, MVTR, taped seams… waterproof jackets come with a lot of jargon. So here’s what those terms actually mean 👇
💧 WHAT DOES 10K WATERPROOF MEAN?
The first number refers to the fabric’s hydrostatic head - its resistance to water pressure.
10K = 10,000mm water column
In simple terms, a higher rating means the fabric can withstand more water pressure before water begins to pe*****te.
💨 WHAT DOES THE SECOND 10K MEAN?
That’s breathability.
It’s commonly measured using MVTR (Moisture Vapour Transmission Rate), which measures how much moisture vapour can pass through a square metre of fabric over 24 hours.
So:
10K/10K = 10K waterproofing + 10K breathability
🧵 WHAT ARE TAPED SEAMS?
Waterproof fabric isn’t the whole story. Stitching creates tiny holes where panels are joined together, so taped seams seal these areas to help prevent water getting through.
Fully taped = all seams sealed
Critically taped = key seams sealed
🤔 IS 20K WATERPROOF BETTER THAN 10K?
Not necessarily.
A higher waterproof rating means greater resistance to water pressure, but it doesn’t automatically mean a better jacket. Breathability, seam sealing, construction and ventilation all affect real-world performance.
❓ IS 10K WATERPROOF ENOUGH FOR RAIN?
It depends on the conditions and how you’ll use the jacket. Heavy rain and pressure against the fabric can put greater demands on waterproof protection.
The takeaway? Don’t just look for the biggest number. Understand what the numbers actually measure.
Read our full waterproof deep dive for more on hydrostatic head, breathability, MVTR, taped seams and waterproof ratings.
