What is an EN Power Size?
An EN power size is a standardised rating that tells you how much closing force a door closer can generate. It’s set out in EN 1154, the European standard covering controlled door closing devices, and it exists so that specifiers, contractors and building control can all work from the same reference point rather than relying on manufacturer’s specific descriptions.
Each size is linked to a tested door width and weight, giving a clear benchmark for how a closer will perform once it’s installed.
The Power Size Scale
As a general guide, power sizes correspond to the following approximate door widths.
Size 1: up to 750mm Size 2: up to 850mm Size 3: up to 950mm Size 4: up to 1100mm Size 5: up to 1250mm Size 6: up to 1400mm Size 7: up to 1600mm
Many closers on the market are supplied as adjustable across a range, commonly size 2 to 4 or size 3 to 6, which allows a single unit to be set on site to suit the actual door rather than needing a different product for every width.
Why Getting It Right Matters
Specifying too low a power size can mean that a door won’t close and latch properly, which is a serious issue on any fire door where full closure is essential for compliance. Specify too high, and the door can feel heavy or slam, causing discomfort for users and unnecessary wear on the frame and hardware over time.
Power size also needs to be considered alongside factors such as door weight, frequency of use, whether the door is fitted with intumescent seals, and any local wind or pressure conditions that could affect closing.
Beyond the Basic Rating
EN 1154 also tests and certifies closers for durability, corrosion resistance and, where relevant, fire door suitability. A correctly specified power size is the starting point, but the full certification confirms the closer will keep performing reliably across its expected lifecycle.
Making the Right Choice
Choosing the correct EN power size isn’t just a technical formality, it’s what ensures a door closes safely, consistently and in line with its fire strategy for years to come. If you’re unsure which power size suits your project, our team is always happy to talk through the door schedule with you.