Naismith's Rule is a rule of thumb that helps in the planning of a walking or hiking expedition by calculating how long it will take to walk the route, including ascents. The rule was devised by William W. Naismith, a Scottish mountaineer, in 1892. The basic rule is as follows: Allow 1 hour for every 3 miles (5 km) forward, plus ½ hour for every 1000 feet (300 metres) of ascent. (When walking on poor terrain, allow 1 hour for every 2.5 miles -4 km - forward, instead of 1 hour per 3 miles.) Will Gadd has added a few rules of his own that are more climbing and alpine specific:
a) Ten pitches of climbing fresh ice will pretty much take all day. Ten pitches of gear climbing at my trad standard will pretty much take all day.
b) I can generally run about ten minute miles on almost any trail out there if averaged over the course of a few hours. Except when I can't.
c) Any approach not involving trails will generally take a "practice" approach to find the way in.
d) Eat every hour at the minimum or suffer.
e) Take twice the food and half the water in winter as you do in summer.
f) If your winter pack is bigger than 45L you're backpacking, not climbing fast. While, a pack smaller than ten liters is a purse.
g) The farther you are from home the more you'll get done in the wrong conditions. Put another way, visiting climbers are often stronger than the locals...
h) Camping is vastly over-rated. Most local trips can be done without camping.
i) As you get older your potential for injury while doing new sports increases and is inverse to your ability to heal from an injury...