How to choose a door closer power size

What the number means

Power size is the industry's shorthand for how much closing force a unit produces, and therefore how large a leaf it can close. It is a scale, not a unit of measurement: size 3 closes a wider and heavier door than size 2, and a size 5 closes more again.

Our catalogue gives a power size and a maximum door width for every model. Some models give a single fixed size, set at the factory; others give a range, which means the closing force is adjusted on the unit itself.

Start from the leaf, not the model

• Measure the width of the door leaf, not the frame opening. This is the figure our maximum-width ratings refer to.
• Get the weight if you can. If you cannot weigh the door, its size, material and thickness are enough for us to estimate it.
• Note whether the door is internal or external, and whether anything makes it exposed — an entrance, a corridor that funnels wind, a stair core with a pressure difference across it.

Width and weight set the minimum. Exposure is what moves the answer up: wind pressure on the leaf is not in any catalogue figure, and a correctly sized closer on an exposed door can still fail to latch.

Why the largest size is not the safe default

A closer sized well above the door produces more force than the door needs in both directions. It slams on closing, and it takes real effort to push open. On a public building that is an accessibility problem; everywhere else it is the reason someone unscrews the closer and throws it away.

If the right size is genuinely uncertain — a door you have not measured, or a mixed batch of openings — an adjustable-power model is the honest answer. One unit covers a span of door sizes and can be tuned once it is on the door.

Where our catalogue is not precise

A few models list more than one door-weight figure, or a weight range whose relationship to the power sizes is not stated. We show those as the catalogue gives them rather than picking one, and the model page says which case applies. If you need a firm figure for a specification, ask us and we will confirm it with the factory.