High-visibility clothing in the UK is certified to EN ISO 20471. The standard sorts garments into three classes by how much fluorescent background fabric and retroreflective tape they carry — the more there is, the more conspicuous the wearer, and the higher the class.
What the classes mean
- Class 1 — the lowest level, for the lowest-risk environments. Typically hi-vis trousers on their own. Minimum 0.14 m² of background fabric and 0.10 m² of reflective material.
- Class 2 — mid level, the familiar hi-vis vest or tabard. Minimum 0.50 m² of background fabric and 0.13 m² of reflective material.
- Class 3 — the highest level and the most conspicuous. Minimum 0.80 m² of background fabric and 0.20 m² of reflective material. In practice a garment must have sleeves with reflective bands to reach Class 3 — a sleeveless vest cannot.
How to choose the right class
The right class depends on the traffic speed near you and how much other risk is present. As a rule of thumb: low-risk areas away from traffic may accept Class 1; most general site and roadside work calls for Class 2; and high-speed roads, motorways and rail environments require Class 3 for maximum visibility, day and night.
Combining garments to reach a higher class
Classes can be added together. A pair of Class 1 hi-vis trousers worn with a Class 2 waistcoat provides an overall Class 3 ensemble, as long as both garments are certified and worn together. This is a practical way to give crews full Class 3 protection while keeping them comfortable in warm weather.
Keep it compliant in service
Hi-vis only works if the fluorescent fabric stays bright and the reflective tape stays intact. Garments fade and tape cracks with washing and wear, so inspect regularly and replace anything that is dirty, faded or damaged — a washed-out jacket may no longer meet the class on its label.
This is general guidance. Always follow your own risk assessment and any client or sector-specific hi-vis requirements (for example rail RIS-3279-TOM).