Naismiths Rule explained
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Published 2024-05-31
Naismiths original Rule is “an hour for every three miles on the map, with an additional hour for every 2,000 feet of ascent”. The modern version of that is 5km or approximately 3miles an hour plus 10 minutes for each 100m or 330ft rise. For shorter routes you can use 12 minutes per km and 1 minute for each 10m ascended.
But the question has to asked: Is Naismith's Rule accurate – No.
There are two main reasons for this lack of accuracy. The first reason is variability – this is because we’re all built differently - some people are taller/shorter, older/younger, faster/slower, etc. So you can’t assume that different people will walk over the same piece of ground at the same speed.
The second reason is not accurate is that it was never meant to be accurate. In 1892 Naismith called his idea a rule – this word has changed over the years and now we would call it a rule of thumb (which has absolutely nothing at all to do with beating your wife with a certain sized stick) Anyway, a rule of thumb is something which has been gained from experience and practice, rather than a calculation. So it’s sometimes correct but not always.
Also Naismith’s doesn’t take into account the type of terrain you’re walking over. Walking through deep snow, up a steep slope, changes in visibility, your fitness, the weight of your rucksack, etc. are just a few of the many things which will alter the time it takes to walk somewhere.
But one thing has to said, even though Naismith’s isn’t very accurate for most people, it is brilliant for one thing and this is that it’s very simple and it can be adjusted for your own situation in most locations and types of terrain. So instead of just guessing how long you’ll be walking for, Naismith’s provides a very simple way of roughly estimating the time you’ll be walking.
Over the years there have been many attempt to improve it – these are known as corrections.
Some of the corrections are obviously wrong – but don’t forget that Naismith’s is just a rule of thumb, which is basically just an estimate and so any changes to it will be equally inaccurate.
So let’s go over just a few of the corrections.
We’ll start with Tranter’s Correction – which (just my opinion) I think is based on a very wrong assumption. Tranter’s is based on how fit you are and the fact that people slow down at the end of the day as they get tired. It puts everyone into one of six numbered brackets 15, 20, 25, 30, 40 or 50. Using a calculation you can use those numbers to calculate your walking distance over a number of hours. The lower your bracket the slower you’ll walk.
The reason I think Tranters is wrong is that the bracket you’re put in to is based on how fast you walk 800m with an ascent of 300m. (my phone calculator tells me that’s a slope of 20.55 degrees – which is quite steep. But I would say that speed isn’t the same as stamina, which you need for a full day walking in the hills.
The Aitken correction changes the speed people walk on different terrain surfaces, as an example it lowers the walking speed from 5 to 4km per hour once you leave a path or track.
The Langmuir correction basically says that you speed up on easy downhill slopes – You still use Naismith’s but you deduct 10 minutes per 300m of descent for slopes between 5 and 12 degrees. It also says that you slow down on steeper uphill sections – so add 10 minutes to Naismith’s for each 300m descent for slopes greater than 12 degrees.
I would suggest that we all know how fit we are and if you’re a hill runner then 5km per hour for a whole day will be no problems. But for everyone else – I would suggest that you use Naismith’s as a minimum time to get somewhere.
So give it a try and see if it works for you. Don’t forget Naismith’s rule is 12 minutes per km and then add 10 minute for each 100m rise.
All Comments (21)
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This is golden, it should be compulsory. Especially for those who keep the rescue groups so busy 🙂
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Thank you very much for your consistently helpful and interesting content. In Switzerland, we use a similar rule: 15 minutes for 1 kilometer, 15 minutes for 100 meters uphill, and 15 minutes for 200 meters downhill. The rule is from the SAC (Schweizer Alpen-Club). Perhaps it is based on the same rule as in Britain. We use this rule to plan a route approximately. The keyword is "approximately."
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A geography lesson, combined with a history lesson and wife-beating (allegedly). A wonderful,informative video.
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Very interesting. I will have to add in other "derating" factors, a term we use in electrical work. I could calculate for the distance, gain, and etc, but would have to add time for starting altitude. If the trailhead is at 8000' or 9000' (Rocky Mountains, in USA) to begin with the thin air slows most people down more. Then I have to add time for gawking at marvelous views and photographing wild flowers. Being almost 70 years young I don't stay married to final destinations any more. I go as far as I like and if I don't reach a target no big deal. I've enjoyed all of the distance I covered .
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Love the practicality and the history mixed. Keep it up - it's a joy to watch!
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Thanks I might watch this again to take more in . Most of my SOTA hikes are roughly 16 minute per Km. I am 71 carrying 8kg of kit and ppe, now I can also add the time for altitude gain because as the country gets steeper i end up closer to 20 minutes per Km.
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Never stop waffling my friend, it makes your videos all the more entertaining. 🙂 I've used Atkins correction for so long now that I interpret it as Naismiths rule. This video was a good reminder how things can get lost in translation over time. The only advice I would offer is, rather than 10 minutes per 100m I just add 1 minute for each contour line crossed uphill as it makes for an easier calculation. That way you only count the contours and not calculate over 100m. So my formula is: Total time = (4km per hour + 1 minute for each contour crossed uphill). I did try minusing a minute for each contour crossed downhill for a while but it was never particularly accurate. I sometimes minus 30 seconds for downhill contours which is more accurate but is very specific to me I feel. As a local lad to you, I look forward to bumping into you on t' hills one day maybe. 🙂
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This was delightful and informative. Thank you so much.
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I always enjoy your YouTube videos, thanks for another informative and interesting video.
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Very instructive, great channel. When I’m walking on Dartmoor or similar terrain I know on average I walk at 2.5 miles an hour, including short breaks for navigation, food, etc. I use that rule of thumb and then use Naismith if I’m in any different kind of Terrain, conditions, etc. seems to work.
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I have not heard of this! Very useful! On the corridor route; going up Scafell Pike the other day, my son said we had 4km left to walk. I thought east!!!! It was fascinating to find out that this was wishful thinking. This will be useful in winter!
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I just came across the following post in a technology forum. I found it very interesting and relevant to the topics you usually cover, so I'm sharing it with you. It might inspire a new episode for your channel that discusses the issue raised in the post. From a MacRumors thread on iPhone hiking trails maps, written by user "ChrisA": I was hiking in Yosemite, about 2 or 3 days from the trailhead. There is zero cell service there, even at the trailhead I was by myself. The trail mostly followed a river. Then I meet these two girls (OK I'm an old guy so everyone only 40 looks young, they were likely in their 20s so clearly "born in the digital age") One of them shows me her iPhone which has a map and a blinking "you are here" dot. And she asks me "Where are we?" Clearly, she knew the blinking dot was the location and that she was standing on a trail but she meant, is it a hard or easy walk to a place to camp, will the canyon open up and get wider, and how long of a walk is that? All this was clearly on her map but all she was seeing was a useless-to-her "you are here". Think about it, if you can't read a topo map, the "you are here" dot is as useless as if you drew an "X" on the ground and I told you "You are standing on an "X". You are always "here" no matter where you go and the GPS will always uselessly tell you that you are standing in the place you are standing. Seriously all she saw was a screen filled with usless wiggly lines and a flashing dot. She could also see the direction she needs to walk. I think this is a problem with people who depend on these electronic gadgets, You don't need "turn by turn" directions when the plan is to walk for two days on the same trail. Because of these electronic maps, there are now maybe as many people like this with zero map-reading skills. Maybe this is an opportunity for Apple or someone else to apply AI to topo map reading. You could ask the AI "when will we come to the next good place to stop for lunch and a rest with a flat space by the water? The system then makes a custom graphic. (let's not talk about what happens if you are 20 miles from the road and you drop your phone in the water and can't read maps and don't own a compass.)
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Excellent explanation. Enjoyed the history lesson as well.
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Excellent as always! Thank you 😊👍🏻👍🏻😎
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Great video. Thanks. I have always used the maxim “ average marching speed of 3 miles per hour” as my basic guide. Has worked for me.
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Another very interesting video. Thank you
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Great informative video thanks for the info.
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In Poland, all the mountain trail markings use 12 minutes per kilometre and 12 minutes per 100 metres, which is quite accurate for an average, healthy person. It doesn't work well for steep climbs and steep descents, where you have to slow down.
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Great video, usual. Great channel. Warm greetings from Oregon, USA. We recently had the opportunity to do a lot of walking in southwestern England (Wiltshire), and it rekindled my love of walking. I will try to use Naismith's rule on future walks in the Pacific Northwest, but I will be missing the public footpaths, sheep poop and all.
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Thanks for a very informative video, a waffle, and a refresher in 4th grade arithmatic .. Cheers 🙂
