Two simple expressions are derived for daylight design. The first yields the limiting depth, from front to back of a side-lit room, to ensure reasonably even daylighting. The second expression is applicable only if this limiting depth is not exceeded; it yields the average daylight factor. A step-by-step sequence is proposed for daylighting design. The two expressions provide a structure for this sequence, which encourages architects and consultants to pay due regard to natural lighting considerations at various stages between inception and completion of a building design.