What waterproof rating (mm) do I need for my market and use case?
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- Issue Time
- Nov 6,2026
Waterproof rating measures hydrostatic head - the water column pressure a fabric withstands before leaking (ISO 811). Choosing the right level matters commercially: overspecifying raises fabric cost, underspecifying generates returns.
Practical tiers:
- 5,000mm: light rain, drizzle, urban commuting, wind protection priority. Adequate for shower-proof shells and spring jackets.
- 10,000mm: all-day hiking rain, general outdoor use - the workhorse tier for most hiking ranges and a safe default for mixed European markets.
- 15,000-20,000mm: sustained mountain rain, ski and snow pressure points (seat, knees, pack straps), premium positioning.
- 20,000mm+: expedition and professional use, where marketing claims also matter at retail.
Three things that decide whether the rating survives real use:
- Seam sealing: stitching is the weak point - critical seams must be taped or bonded regardless of rating.
- Breathability: pair the rating with a RET target (RET below 13 is excellent; below 6 for high-output activity) or g/m2/24h figure.
- DWR maintenance: a fluorine-free (C0) DWR keeps the face fabric from wetting out, which preserves breathability in the field.
For Northern European and alpine retail we typically recommend 10,000mm+ for core hiking styles and 20,000mm for technical ski lines; US West Coast and urban programmes can sit lower to protect margin.