The short answer
A fair amount, on uneven ground. Cars cannot enter most medina lanes, so you walk from the nearest gate to your riad and between sights, often on cobbles and steps. A half-day guided walk is rated easy, but it is still several hours on your feet. Good shoes, rest stops and a car for the longer hops make it manageable.
In more detail
The medina is a walking city. The lanes are too narrow for cars, so taxis and drivers stop at the nearest gate and you go on foot from there. Sights such as the souks, Ben Youssef Madrasa, the Bahia Palace and Jemaa el-Fnaa are joined by lanes, not roads.
The ground is the tiring part, more than the distance. Surfaces are uneven, cobbles are common and steps appear without warning. Bring comfortable walking shoes. In the heat, the same walk feels much longer, so walk in the morning and the early evening.
Our medina and souks walk is a half-day on foot, with a rooftop mint tea stop in the middle, and it is rated easy: light walking on medina cobblestones. Because it is private, the guide sets the pace to yours and can take more breaks.
To cut the walking, use a car between distant sights, a calèche round the ramparts, or a petit taxi to the nearest gate. Tell us when you ask for a quote and we will plan short legs with the car close by.