Course time calculator

How Japanese course times are built

Hiking maps in Japan (the Yama-to-Kogen series, YAMAP, Yamareco) print a course time for every leg. It is built from a simple standard:

15 min per horizontal km  /  10 min per 100 m of ascent  /  5 min per 100 m of descent

Example: 8 km with 800 m up and 800 m down is 120 + 80 + 40 = 4 hours. That is walking time for a "standard" hiker, with no breaks.

Who is the standard hiker?

Course times assume an experienced hiker in their 40s or 50s with a day pack. Visitors used to Naismith's rule will find Japanese course times a little generous on the flat and tight on steep ground. First-timers take 1.2–1.5× the printed time, and that is normal. After one hike, divide your actual walking time by the course time: that ratio is your personal factor, and planning becomes accurate from then on.

Why the sunset margin matters

Most rescues in Japan start the same way: a party runs late, darkness falls, and they lose the trail. Plan to be off the mountain two hours before sunset. From October to February the sun sets between 16:30 and 17:10 in central Japan, so "down by 15:00" is the rule. If the margin drops below an hour, start earlier or fix a turnaround time before you leave.

Estimating breaks

• Short stops: 5–10 minutes per hour, so 30–60 minutes over a 6-hour day
• Lunch: 30 minutes
• Photos, views, toilets: they add up

Breaks come to 20–30% of walking time. The tool's default of 60 minutes suits a 5–6 hour day; add more for longer routes.