The Chronicles of Kedas
On Roads / trails
Level or rolling terrain: 60km
Hilly terrain: 50km
Mountainous terrain: 30km
Off-Road (or unkempt trails etc)
Level/rolling grasslands: 50km
Hilly grasslands: 40km
Level/rolling forest/thick scrub: 30km
Very hilly forest/thick scrub: 25km
Un-blazed Mountain passes: 15km
An average quality horse, of a breed suitable for riding, conditioned for overland travel and in good condition.
Roads and trails are in good condition and up kept by whatever local authority deals with them.
Weather is good to fair, and travelers are riding for around ten hours a day.
Halve these distances for a horse pulling a cart or for a very heavily laden horse (e.g. a fully armoured knight who insists on wearing his armour all day rather than having it stowed on a second baggage horse as would be normal!).
Add half again for specially trained horses and riders who are prepared to push hard (rangers, scouts and messangers, etc…) though do bear in mind that horses cannot be pushed like this for more than a few days at a time. You can add a bit more again to this distance if the breed of horse is exceptionally suitable for this sort of thing, but I’d say 2 to 2.5 times the base is the absolute maximum without some sort of magical assistance!
Poor weather such as heavy rain or wind should reduce distances by about one quarter, and very poor conditions like heavy snow or gale force winds, etc.. should reduce distances by at least half if not more.
Finding a place to ford a small river or swimming your horse across a larger river should knock a couple of miles off the day’s journey, other unique obstacles might have a similar reduction. (as a guide remember a horse walks at around 4 miles per hour (compared to a human average of around 2.5 – 3mph) so if the obstacle takes half an hour to deal with thats a couple of miles lost.