Nearly every outdoor jacket on the market is sold as “waterproof.” Far fewer are sold as breathable — and that gap is exactly where most products quietly disappoint their wearers.
If you’re a brand, dropshipper, or buyer sourcing custom jackets, understanding the difference between waterproofing and breathability is the single most useful thing you can learn before you spec a product. This guide breaks it down and shows you how to choose the right numbers.
They’re Two Different Jobs
- Waterproofing keeps rain out.
- Breathability lets your body’s sweat vapor out.
A jacket can be fully waterproof and completely non-breathable — think of a cheap PVC rain poncho. It keeps the rain off, but ten minutes of walking and you’re soaked from the inside with your own sweat. To the wearer, a non-breathable “waterproof” jacket feels exactly as wet as no jacket at all.
That’s why waterproof is table-stakes, but breathability is what makes a jacket good.
How Each Is Measured
Waterproofing → millimeters (mm)
Measured as hydrostatic head (ISO 811): how tall a column of water the fabric holds before it leaks. Higher = more waterproof.
| Rating | Real-world protection |
|---|---|
| 5,000mm | Light rain, short exposure |
| 10,000mm | All-day rain, general outdoor use |
| 20,000mm | Heavy rain, snow, high-pressure points (pack straps, sitting) |
Breathability → grams (g) or RET
Measured as MVTR (moisture vapor transfer rate, g/m²/24h — higher is better) or RET (resistance to evaporation — lower is better). For a full breakdown, see our guide to breathability ratings (MVTR & RET).
| MVTR | Suitable for |
|---|---|
| 5,000 g | Low-output / casual |
| 10,000 g | Hiking, daily wear |
| 20,000 g | Skiing, climbing, high-output activity |
The “10K / 20K” Shorthand
You’ll see jackets labeled “10K/10K” or “20K/20K.” The first number is waterproofing (mm), the second is breathability (g). It’s the industry’s quick way of stating both ratings at once:
- 10K/10K = 10,000mm waterproof + 10,000g breathable → the workhorse standard for everyday and commuter jackets.
- 20K/20K = 20,000mm + 20,000g → the spec for ski, snowboard, and demanding outdoor use.
When buyers search for a jacket, these are the round numbers they look for. Odd ratings like 8,000mm or 15,000mm rarely match how customers actually shop — so spec to the tiers people recognize.
Construction Matters as Much as the Membrane
A fabric’s rating means nothing if water gets in through the gaps. Two construction details decide whether a “20,000mm” jacket actually performs:
- Taped seams. Every needle hole is a leak. Quality jackets are seam-taped — fully or critically. See fully taped vs critically taped seams.
- Waterproof zippers. A standard zipper is an open channel for water. Waterproof or storm-flapped zippers seal it.
This is why two jackets with the same fabric rating can perform completely differently. When sourcing, confirm the factory controls seam-taping and zipper sealing in-house — outsourced or skipped taping is a common corner-cut.
Softshell vs Hardshell: A Breathability Trade-off
- Hardshell = maximum waterproofing, lower stretch and breathability. Best for sustained rain/snow.
- Softshell = highly breathable and flexible, water-resistant rather than fully waterproof. Best for active, drier conditions.
Many buyers actually need a breathable softshell, not a fully waterproof hardshell. See softshell vs hardshell to match the build to the use case.
How to Spec It When You’re Sourcing
When you brief a manufacturer, don’t just say “waterproof.” Specify both numbers and the construction:
- Waterproof rating — 10,000mm (standard) or 20,000mm (premium).
- Breathability — MVTR 10,000g or 20,000g, matched to the use case.
- Seams — fully taped.
- Zippers — waterproof.
- DWR finish — PFC-free if you sell into the EU or eco-conscious markets.
A capable factory can build to any of these tiers — the right choice is driven by your customer’s activity and price point, not by what’s easiest to produce.
Sourcing Custom Breathable Waterproof Jackets
At PTOUTWEAR, we build custom hardshell, softshell, and 3-in-1 jackets to your chosen waterproof + breathability spec — with in-house seam-taping, waterproof zippers, and PFC-free DWR, ISO 9001 and SGS tested. Standard 10K/10K through Pro 20K/20K, from a 30-piece MOQ (1-piece sampling).
Request a sample with your target ratings and we’ll build to spec.
