Good planning promotes good ethics and safety in the outdoors. Knowing how long you’re expecting to be out is part of good hike planning. But we know many folks who under- and over estimate the amount of time needed for a day’s outing. There’s a way that you can better estimate it, and perhaps give an answer when your kids ask “How much farther is it, mom?”
The Naismith Rule
William Naismith was a Scottish mountaineer and guide who developed a time estimating methodology for wandering around the Scottish hills way back in 1892. We first learned about it in the preface to the Second Edition of Gillian Daffern’s Kananaskis Country Trail Guide in 1985. The original Naismith Rule is pretty simple:
For adults, plan on 5 km/hr, plus 30 min for every 300 m of height gain.
Many have offered “upgrades” to the formula. Gillean suggested a formula for youth groups of 4.5 km/hr plus 1 hr for every 450 m climb. There’s something called the “Tranter correction” to the original formula which adjusts for fatigue. There are corrections for gentle or severe slopes. A check on Wikipedia under “Naismith’s Rule” will show you these correction options and more, like the “Aitkin-Langmuir Correction”, “Scarf’s Equivalence” and the “Tobler Hiking Function”. Tobler’s came in a paper called “Non-isotropic modelling speculations on the geometry of geography global spatial analysis“. We would say it’s worth a read, but only if you have a Ph.D.
Does it work for real?
Having engineering in our professions here at the Friends, we have been tracking hikes, and comparing times to Mr. Naismith’s for years. We don’t “correct” times by taking out times for lunches, or for other breaks along the trail.
Our conclusion is Mr.’s Aitkin, Langmuir, Tobler, Scarf and Tranter need to get a better life and just go hiking more. We don’t think any adjustment to Mr. Naismith’s simple rule is needed for general planning purposes.
In the 124 hikes plotted above, Naismith’s rule is 81% accurate in predicting times. Being closet statisticians, we can also tell you that Naismith’s rule will accurately predict hiking time within 8.8%, in 19 hikes out of 20.
What Naismith doesn’t tell you
A more advanced statistician will tell you that Naismith’s 2 factors – distance and height gain – explain 68% of the amount of time a hike will take. Other factors are at play. As a result, we have looked at the “outliers” in the above data (like where Naismith would say it should take 6:50, but it only took 2:50). All are explained by things like the use of bikes for part of the hike, the presence of pikas, moose or other wildlife that we stood around and watched, or other factor that made the day not a “normal” hike. Obviously, statisticians are right (as usual), but 68% is good enough for us.
The best part is that you, too, can start collecting your own data and planning your day to compare. If you find Naismith’s rule doesn’t work perfectly for you, it’s easy to adjust. Plus, by using a good guidebook and a map when you’re on the trail, you can give a good answer to the question that every parent dreads:
“Are we there yet?”
How about other sports?
We have searched, and collected our own data. We have tried. At this point, we cannot offer a predictive tool that will help you plan your mountain bike, XC ski, snowshoe or paddling adventures. We’re happy to share any you have.
Learn more about planning your K-Country adventures here!