Three measurements that mean different things
Ladder length is the frame’s physical length. Standing height is the highest level the manufacturer allows you to stand on. Working reach is an estimate that also includes the person’s height and reach. Never substitute one measurement for another when comparing products.
Measure the job and the space
Measure the area you need to work on and identify where the feet and upper support can go. Indoors, measure ceiling height and available floor space. Outside, think about the path needed to carry, raise and secure a long ladder.
Choose with a margin for comfortable work
The right size lets you work without standing above the permitted level or stretching sideways. If you cannot maintain a suitable position, change the equipment or method. A long-reach tool used from the ground may remove the need for a ladder.
Check transport before checkout
Measure your storage space and vehicle. Include the stabiliser, any protruding hinges and the closed length. The largest model in a product family may be much harder to handle than the model a reviewer describes.
For access to another level
HSE gives specific guidance for securing access ladders and providing a suitable handhold above the landing. Consult that guidance and the manual rather than calculating access requirements from an Amazon “reach” label.