Naismith’s rule helps with the planning of a walking or hiking expedition by calculating how long it will take to travel the intended route, including any extra time taken when walking uphill. This rule of thumb was devised by William W. Naismith, a Scottish mountaineer, in 1892. A modern version can be formulated as follows:
Allow one hour for every 3 miles (4.82 km) forward, plus an additional hour for every 2,000 feet (600 m) of ascent.
The basic rule assumes hikers of reasonable fitness, on typical terrain, and under normal conditions. It does not account for delays, such as extended breaks for rest or sightseeing, or for navigational obstacles. (Wikipedia)
Try setting your own walking speed.