How Long Will a Hike Take? Naismith’s Rule Explained

How long does a 12 km hike with 600 m of climbing take? About 3 hours 24 minutes of steady walking, before a single break. That answer comes from a simple rule a Scottish climber wrote down in 1892.

The rule is called Naismith’s rule, and hill walkers still use it to plan their days. It adds time for distance and extra time for every meter you climb. This guide shows how it works, where it falls short, and how to turn it into a full day plan.

What Naismith’s Rule Says

Naismith’s rule estimates hiking time from two numbers: how far you walk and how high you climb. William Naismith, a Scottish mountaineer, described it in the Scottish Mountaineering Club Journal in 1892. He suggested allowing “an hour for every three miles on the map,” plus one extra hour for every 2,000 feet of ascent.

The modern metric version rounds those figures. Allow 1 hour for every 5 km, then add 1 hour for every 600 m you climb. The formula is short enough to do in your head:

Time (hours) = distance in km / 5 + ascent in m / 600

Naismith checked his rule against a real day out. His route covered 10 miles with 6,300 feet of climbing and took six and a half hours, including short halts. The rule predicts 10 / 3 + 6,300 / 2,000, which is 6.48 hours. That is almost a perfect match.

Note what the rule assumes. It was written for walkers “in fair condition” on easy outings. It describes a fit adult on a decent path in good weather, not a scramble or a snowy ridge.

How to Turn a Route Into Hours

You need only a map or a trail listing to run the numbers. Most trail apps and guidebooks list total distance and total elevation gain. Those two figures feed straight into the rule.

1. Find the total distance. Use the full round trip, not just the distance to the summit. An out-and-back trail of 6 km each way is 12 km.
2. Find the total ascent. Add up every climb on the route, including small ups on the way back. Total ascent is often higher than summit height minus trailhead height.
3. Work out walking time. Divide the distance by 5 km/h. Use 4 km/h for a slower walker or a heavy pack.
4. Work out climbing time. Divide the total ascent by 600. Every 100 m of climbing adds 10 minutes.
5. Add the two parts. The sum is your moving time. Convert the decimal to minutes by multiplying the fraction by 60.

Here are three quick examples, all checked against the formula:

Notice the second route. It is 4 km shorter than the first, yet it takes nearly as long. The extra 300 m of climbing adds half an hour on its own.

Why Does Climbing Cost So Much Time?

Climbing costs time because lifting your body uphill takes far more effort than walking on flat ground. Naismith’s rule says 600 m of climbing takes as long as 5 km of flat walking. So each meter up is worth about 8 meters forward.

A statistics professor named Philip Scarf turned this idea into an “equivalent flat distance.” In his version, each unit of climb counts as 7.92 units of distance, which rounds to an easy 8 to 1. A route of 10 km with 500 m of climbing then walks like about 14 km of flat ground.

The chart below keeps the distance fixed at 10 km and changes only the climb. The time more than doubles.

This is why distance alone is a poor guide. A short, steep peak can take longer than a long valley walk. To see how steep a route is before you go, the Elevation Gain Per Mile Calculator shows the climb packed into each mile.

In imperial units, 1,000 feet of climbing adds 30 minutes. At 3 mph, each flat mile takes 20 minutes. To switch between pace and speed for your own walking, see our guide on converting minutes per mile to mph.

What Does the Rule Leave Out?

Naismith’s rule leaves out descents, rough terrain, heavy loads, fitness, and every kind of stop. It is a clean baseline for a fit walker on a good path. Real days rarely match those conditions, so many walkers treat the result as a minimum time.

Descents

The basic rule adds nothing for going downhill. In 1984, a writer named Langmuir added corrections for descent. On gentle slopes of 5 to 12 degrees, subtract 10 minutes for every 300 m of descent. On slopes steeper than 12 degrees, add 10 minutes for every 300 m instead.

Take the 12 km route again and assume it drops 600 m on the way back. On a gentle path, that saves 20 minutes. On a steep, loose path, it costs 20 minutes, which turns 3 hours 24 minutes into 3 hours 44 minutes.

Groups and Fitness

A group moves at the pace of its slowest member. Langmuir suggested a slower formula for groups: 4 km/h plus 1 hour for every 450 m of ascent. The same 12 km route with 600 m of climbing then takes 3 hours plus 1 hour 20 minutes, or 4 hours 20 minutes.

Terrain and Heat

Bog, scree, snow, and faint paths all slow you below the rule. Heat does too. Grand Canyon rangers warn that easy downhill hiking lures unprepared hikers into trouble. They also call the summer climb back out extremely strenuous. On any route that ends with a climb, plan the return as the slow half.

From Moving Time to a Full Day Plan

Moving time is only the start. A real day adds stops for water, food, photos, map checks, and blister care. Pick an allowance you trust, then add it on top of the Naismith number.

Here is one way to do it. Take a 10-minute stop for each full hour of moving time. The 12 km route has 3 full hours of moving, so that adds 30 minutes. Your day becomes 3 hours 54 minutes, close to the 4 hours the calculator page suggests.

Next, compare the finish time with the day’s sunset. The NOAA Solar Calculator gives sunset times for any place and date. For long routes, our guide on when to turn around on a hike shows how to set a firm deadline from your return time. Always tell someone your route and when to expect you back, and pack a headlamp in case you run late.

Try it with your own route: enter distance, ascent, and flat speed in the hiking time estimator, then add your breaks on top.

Hiking Time: Frequently Asked Questions

Sources and Further Reading

This article is general hike-planning education. Conditions on the day always come first, so check the weather and trail reports before you go. Reviewed for accuracy by Prof. Dr. Khalil Mudassar, PhD. Last updated September 27, 2026.