To build a set of steps that are comfortable to use, you should try to make them as wide and inviting as possible; narrow stairs can be dangerous to use and are visually unappealing.

Steps are made up of two main components:

1. The Tread

This is the part of the stair that is stepped on. It should be as wide as practicable, but certainly never smaller than 25 cm (10 in). Most users will find a tread depth of 45 cm (18 in) most comfortable to use.

2. The Riser

This is the vertical portion between steps. This should vary in height from 10 cm (4 in) to about 20 cm (8 in) - anything much higher will feel more like mountaineering! An ideal height is 15 cm (6 in).

Tread to Riser Ratio

Not only is it important to choose a comfortable tread and riser depth and height, but they must be in proportion to each other. In general, the proportions should be as follows:

tread width + double the riser height = 65 cm (26 in)
i.e.
tread width = 65 cm (26 in) - (2 x riser height)

This means that if your riser is 15 cm (6 in), you should have a tread width of 35 cm (14 in):

tread width = 65 cm (26 in) - 30 cm (12 in)

You may add on 2.5-5 cm (1-2 in) onto this tread width allowance for an overhang.