Naismith’s Rule: How to Predict Hiking Time

Naismith’s Rule

Have you ever looked at the kilometers/miles of a hike and wondered how long it will take to finish? In 1892, a Scottish mountaineer named William Naismith devised a rule to help predict this. Naismith’s rule goes like this: a hiker who isn’t carrying any weight or stopping for breaks will walk approximately 5 kilometers an hour (3 miles per hour). That’s 1 km for every 12 minutes on flat land or 1 mile for every 20 minutes.

I’ve found this rule of thumb to be accurate and I plan my longer hikes based on this calculation. Before you do, make sure to take into consideration the following things:

Two men are hiking with their backs to the camera across frozen ground. The sky is blue and the landscape is red-brown with snow.

Factoring Elevation

The elevation of a hike can change the time needed to complete it. To factor in elevation add an extra 1/2 hour for every 1000 feet climbed. Topographic maps have contour lines that denote elevation. Your map’s index will tell you the distance between contour lines. This is known as the contour interval. Knowing the contour interval will make it easy for you to calculate the elevation.

You also need to consider how a decline can affect the time needed to complete a hike. A gentle decline will save you approximately 10 minutes per 1000 feet. A steep decline will add about 10 minutes per 1000 feet.

Other Considerations

There are other factors to consider when calculating time. These include a person’s fitness, type of terrain, weather, weight carried, and how many breaks a person takes. For example, it’s going to take more time to hike on a windy day on rough terrain than on a clear day on flat terrain. There is no specific rule for these considerations but you should give yourself extra time.

Adapting Naismith’s Rule

The best way to determine the amount of time needed to complete a hike is to know your own pace. You can determine this with a stopwatch on a 1 kilometer or 1 mile stretch. Make sure to repeat the exercise when you are tired. This will give you a more accurate estimate. Remember, when hiking with others, you need to measure hiking time based on the pace of the slowest person in your group.

Stay Safe

To be safe, always give yourself extra time to complete a hike. There’s always a chance of encountering a delay. I was in one scary situation where my hiking party got lost. We didn’t give ourselves any extra time for a situation like this. We were also ill-prepared (no headlamps, flashlights, or other supplies). Once we managed to re-oriented ourselves, we ended up rushing to get off the trail before dark. This was a dangerous situation that could have been easily prevented.

If you like hiking, check out my post on winter layering. It discusses how to stay warm on winter hikes.

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