Jackets are full of numbers—5k, 10k, 15k mm waterproof. But what do they actually mean on a cold, wet day? Here’s the simple breakdown so you know what you’re buying.
If you’ve ever scrolled a product page and seen “10,000 mm waterproof” or “15k shell” and thought, “Is that good?”, this guide is for you. We’ll explain what waterproof ratings are, how they’re tested, and which rating you realistically need for the weather you face.
What Is a Waterproof Rating?
Waterproof ratings are usually measured in millimetres (mm) using a “hydrostatic head” test. In simple terms:
- A column of water is pressed against the fabric.
- The height of the water column (in mm) that the fabric can withstand before leaking is its waterproof rating.
So a 10,000 mm rating means the material can handle the pressure of a 10-metre column of water before it starts letting water through.
Important: The rating is about the fabric in test conditions. Real-world performance also depends on seams, zippers, wear, and how you use the jacket.
Waterproof Rating Levels (Plain English)
| Rating (mm) | Technical Level | Real-World Use |
|---|---|---|
| 0–5,000 mm | Water-resistant | Light rain, short exposure. Fine for quick dashes, not storms. |
| 5,000–10,000 mm | Waterproof (basic) | Moderate rain, daily use. Good for commuting and short hikes. |
| 10,000–15,000 mm | Waterproof (advanced) | Heavy rain, wet snow, longer exposure. Great for serious outdoor use. |
| 15,000–20,000 mm | Storm-grade | Prolonged heavy rain, mountain conditions, harsh weather. |
| 20,000+ mm | Extreme | Expeditions, constant exposure, very high pressure from pack straps, kneeling, etc. |
Waterproof vs. Water-Resistant vs. Rainproof
Brands love to use soft language. Here’s what it usually means:
- Water-resistant: Handles light moisture and drizzle. Will soak through in sustained rain.
- Waterproof: Fabric is tested to a specific mm rating. Can handle proper rain if seams and zips are done right.
- Rainproof / Stormproof: Built to handle heavy, continuous rain and wind with sealed seams and protected zippers.
Reality check: A “waterproof” fabric with cheap seams and open zippers is still a leaky jacket.
It’s Not Just the Fabric: Seams, Zippers & Coatings
Even a 15,000 mm fabric will fail if water can sneak in elsewhere. Three details matter just as much as the rating:
1. Seams
- Unsealed seams: tiny needle holes let water in over time.
- Taped / sealed seams: protective tape covers stitching so rain can’t creep through.
2. Zippers
- Standard zips: often leak where water runs down the front.
- Covered or sealed zips: storm flaps and seal strips block water at the entry points.
3. DWR (Durable Water Repellent) Coating
- Makes water bead and roll off instead of soaking into the outer layer.
- Wears down over time, but can be refreshed. The deeper fabric rating still matters underneath.
Waterproofing vs. Breathability
The more sealed something is, the less it breathes. That’s why some heavy-duty shells feel like wearing a plastic bag.
Breathability is usually measured in how many grams of water vapor can pass through a square metre of fabric in 24 hours (g/m²/24h). You don’t need the exact number—but you do need balance:
- If you’re working, hiking, or moving a lot, you want waterproof and breathable.
- If you’re mostly standing still in brutal conditions, you might accept less breathability for more protection.
Which Waterproof Rating Do You Actually Need?
| Use Case | Recommended Rating | Example Conditions |
|---|---|---|
| City commuting, light rain | 5,000–10,000 mm | Short walks, bus stops, shopping runs. |
| Hiking & daily outdoor work | 10,000–15,000 mm | Hours outside, steady rain, wet snow. |
| Fishing, hunting, mountain weather | 10,000–15,000+ mm | Cold wind, heavy showers, exposed terrain. |
| Storms, harsh coastal weather | 15,000–20,000 mm | Sideways rain, strong wind, long exposure. |
| Expeditions & extreme use | 20,000+ mm | Serious, continuous exposure under load. |
Where Lazarel Jackets Fit on the Scale
We design our outerwear around real weather, not catalogue photos. Here’s how some of our key jackets fit into the waterproof story:
~10,000 mm waterproof rating
All-round winter use
Ideal for men who need one jacket for work, hiking, and daily wear in real rain and cold.
~15,000 mm waterproof rating
Storm-ready shell
Built for harsh, wet climates and long exposure to heavy rain and wind.
Rainproof hardshell with sealed seams and zippers
Serious storm protection
Designed for days when the forecast says not to go out—and you go anyway.
Waterproof shells for your legs
Full system
Because a 15,000 mm jacket doesn’t help if your legs are soaked.
Simple rule: choose the rating for your worst weather, not your best day. It’s better to be over-prepared than wet and freezing halfway through the job.
Ready to Pick the Right Waterproof Level?
Now that you know what the numbers mean, you can choose gear that matches your weather—not just the label. Start with a jacket built for your conditions, then complete the system with waterproof pants or a full set.