The waterproof rating of a fabric is usually classified according to its hydrostatic pressure (mmH₂O), which is the main indicator of a fabric's resistance to water penetration. Generally speaking, the higher the hydrostatic pressure, the stronger the waterproof performance of the fabric. Ordinary waterproof clothing for daily life typically has a hydrostatic pressure of 1000-3000 mmH₂O, suitable for light rain or short-term water contact; professional outdoor waterproof fabrics can reach a hydrostatic pressure of 5000-10000 mmH₂O, suitable for prolonged rain, snow, or humid environments.
Waterproof ratings are generally classified into four levels: low, medium, high, and ultra-high waterproof:
Low waterproof: Hydrostatic pressure less than 1000 mmH₂O, suitable for light daily waterproofing, such as umbrellas or lightweight jackets.
Medium waterproof: Hydrostatic pressure 1000-3000 mmH₂O, suitable for urban outdoor wear or short-term rainy conditions.
High waterproof: Hydrostatic pressure 3000-5000 mmH₂O, suitable for outdoor sports such as hiking and mountaineering.
Ultra-high waterproof: hydrostatic pressure exceeds 5000 mm, suitable for extreme climates, professional mountaineering equipment, or protective clothing.