In reply to 2E0XTL:
You can look up Naismiths Rule. This gives you some figures for how long it takes to walk on good ground, how long each 1m of ascent takes and how to derate this for poor ground (tussocks, bog, snow, ice, irate livestock). You can tweak the numbers based on whether you have the physique of a slab faced killer like Jason Bourne or if you are a bit lardy like me.
For me, 1km = 12mins and 10m ascent = 1min.
A 5km walk climbing 500m takes me (roughly) 60+50 = about 110mins or 2hrs. Don’t forget comfort breaks, changing layers, drinks, photos etc. can add a lot to the time.