The number of first aiders needed is determined by a combination of the number of people you employ, the level of hazard that your operations present, the layout and size of your workplace and work patterns such as shifts. The number differs from employer to employer and a thorough risk assessment is required to determine what is appropriate for your operation.

​

As a rule of thumb, if you operate at a higher hazard, you should have 1 first aider with a first aid at work certificate for every 50 people employed on site at all times. For lower hazard employers, it is 1 first aider for the first 25 people employed on site at all times, then 1 extra for every 100 people employed.

​

If you operate over several floors, a large site or have a shift pattern, you need to ensure the same provision is provided across your whole site and at all times your workplace is open. If you have a multi-use site that has a variety of operations, for example an office plus light manufacturing on site, you need to ensure that enough trained first aiders are provided based on the varying hazards of different parts of your site. The HSE also advises that you take into account if parts of your site are open to members of the public and ensure sufficient first aiders are provided.

​

​