Hi Mogens,

The flight parameter “length” refers to the distance from the first nosing to the back edge of the landing step.

When there is no landing step the length of the stair goes up to the last nosing.

This means that you input the size of the stair well with no landing step the last step is the floor joist and floor.

If you add a landing step the back of the step will meet the floor joist.

Always put a landing step if possible.

Have a look at my ebooks ‘Stair basics” and “Stair Design Preliminaries” that you can download from the members library here:

https://wooddesigner.org/membe…..airs/core/

However, the width of the stair shouldn’t change when you add a landing step.

All the best,

Ness