EN 343 Waterproof Rating Explained: What 3/3 Actually Means
The short answer
EN 343 grades rain protection on two axes: the first digit is water penetration resistance (1 to 3, where 3 is the highest) and the second is water vapour resistance or breathability (1 to 3). So 3/3 means maximum rain protection and maximum breathability, while 3/1 means fully waterproof but not breathable. The X notation, such as 3/X, means the garment was not tested for breathability.
The number people misread most often is the second one. A 3/1 jacket keeps rain out and traps sweat in, which is why outdoor crews still complain about being wet.
Last updated: September 2026.
Key takeaways
- Read EN 343 as two numbers: rain resistance first, breathability second.
- 3/3 is the highest combination; 3/X means waterproof with no breathability claim.
- Waterproof and water-repellent are different things. Water-repellent fabric sheds light rain; waterproof fabric resists penetration under pressure.
- Seam sealing matters as much as the fabric. Unsealed seams fail the test.
- Breathability is what crews actually notice on a long shift.
1. Standard vs use case vs purchasing notes
| Rating | Meaning | Typical use case | What to check when buying |
|---|---|---|---|
| 3/3 | Highest rain resistance and highest breathability | Highway crews, utilities, outdoor work in heavy rain | Sealed seams, membrane quality, cost premium |
| 3/2 | Fully waterproof, moderate breathability | Construction in wet climates | Balance of cost and comfort |
| 3/1 | Waterproof but minimally breathable | Short exposure, low activity | Suitable only for intermittent use |
| 3/X | Waterproof, breathability not tested | Budget rain gear | Do not claim breathability in your own marketing |
| 2/2 | Moderate rain resistance | Light rain, urban logistics | Confirm the customer's rain exposure |
| 1/1 | Basic protection | Occasional showers | Not suitable for sustained rain |
2. Waterproof, water-repellent and seam sealing
| Property | Test focus | Practical meaning |
|---|---|---|
| Water penetration resistance | Fabric resists water under pressure | The garment keeps rain out |
| Water vapour resistance | Moisture vapour passes through | The wearer sweats less |
| Water-repellent finish | Water beads on the surface | Helps in light rain, wears off with washing |
| Seam sealing | Taped or welded seams | Without it, water enters through the stitching |
| Closure protection | Storm flap over the zip | A common failure point in heavy rain |
3. What to specify on a purchase order
| Item | Specification to write | Why |
|---|---|---|
| Rating | "EN 343 3/3" or the level your risk assessment requires | Prevents a 3/1 jacket arriving when comfort matters |
| Seams | Fully taped, stated explicitly | Sealing is a cost item suppliers may remove |
| Fabric and membrane | Composition, GSM and membrane type | Determines both durability and breathability |
| Hi-vis combination | EN ISO 20471 class alongside EN 343 | Wet-weather hi-vis is usually dual certified |
| Care | Washing instructions that preserve the finish | Water-repellent finishes degrade with wrong washing |
4. Frequently asked questions
What does EN 343 3/3 mean?
The first 3 is the highest level of water penetration resistance and the second 3 is the highest level of breathability, so a 3/3 garment is both fully waterproof and the most breathable in the classification.
What does 3/X mean on a rain jacket?
It means the garment passed the highest water penetration test but was not tested for water vapour resistance, so no breathability claim can be made.
Is EN 343 the same as waterproofing?
It is the standard that grades waterproofing and breathability. A garment can be sold as rainwear without EN 343, but then there is no verified performance level.
Do seams need to be taped?
Yes, for any garment claiming meaningful water resistance. Water penetrates through unsealed stitching, which is why seam sealing is tested and specified separately.
Can a jacket be both hi-vis and waterproof?
Yes, and it is common: the garment carries EN ISO 20471 for visibility and EN 343 for rain protection, with both ratings printed on the label.
How do I know if breathability is worth the extra cost?
If the wearer is active for a full shift in rain, yes. For occasional exposure or light duties, a 3/2 or 3/1 garment is usually sufficient.
Get rain protection quoted with the right rating
Tell us the climate, the activity level and the visibility requirement, and we will quote the correct EN 343 rating with the EN ISO 20471 class where needed.
