Hiking Time Estimator (Naismith's Rule)

Enter the distance in miles and the total elevation gain in feet. Use total ascent, adding up every climb, not the difference between the lowest and highest points: a ridge walk that climbs 1,500 ft twice has 3,000 ft of gain. Here, 10 miles and 3,000 ft.

Leave the correction on Naismith Only and the result is 4h 50m, with the base Naismith time showing the same figure.

Switch to Aitken and pick the terrain. On paths, tracks or roads nothing changes, still 4h 50m, because Aitken keeps Naismith's 3 mph on made-up ground. Choose rough or off-track and the flat pace drops to 2.5 mph: 10 ÷ 2.5 + 1.5 = 5h 30m, forty minutes longer for the same map distance.

Switch to Tranter when you know roughly how fit you are. Pick the fitness row that matches the time you take to climb 1,000 ft over half a mile, then say whether the ground is rough or very rough. The result row shows the effective fitness level actually used, which tells you whether the terrain setting pushed you down the table.

Finally, add your own breaks. A common habit is to add a few minutes each hour plus a longer lunch stop, and to plan to finish well before dark.

Naismith (1892): Hours = Miles ÷ 3 + Feet of ascent ÷ 2,000. The metric version, 5 km/h plus 1 hour per 600 m, gives almost the same answer: 3 mph is 4.83 km/h and 2,000 ft is 610 m, so the imperial form this calculator uses is about 3.5% slower on distance and about 1.6% quicker on ascent.

Aitken (1977): Hours = Miles ÷ Pace + Feet of ascent ÷ 2,000, where Pace is 3 mph on paths, tracks and roads and 2.5 mph (4 km/h) on all other surfaces. The ascent term is unchanged.

Tranter's corrections: the calculator first works out the plain Naismith time, then reads it against Tranter's table of corrected hours. The table has rows for fitness levels of 15, 20, 25, 30, 40 and 50 minutes (the time to climb 1,000 ft, or 300 m, over half a mile, or 800 m) and columns for Naismith times of 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22 and 24 hours. Between two columns it interpolates in a straight line. Rows for less-fit walkers are shorter, because the original table leaves longer days blank as too much to attempt; beyond a row's last column, and below 2 hours, the calculator extends the nearest segment's slope.

Rough ground under Tranter: following Tranter's own advice to drop one or more fitness levels for uneven terrain, rough moves you one row slower and very rough two rows, stopping at the 50-minute row.

Descent is not in any of these formulas. The calculator adds nothing for going down.

Flat trail: 8 miles with 300 ft of gain. Naismith gives 8 ÷ 3 + 300 ÷ 2,000 = 2h 49m. A fit walker on the 20-minute Tranter row gets 2h 4m, faster than the base rule, because on short days Tranter's table credits fit walkers with more speed than Naismith's average walker.

Steep mountain: 6 miles with 4,000 ft of gain. Despite being two miles shorter, Naismith gives 6 ÷ 3 + 4,000 ÷ 2,000 = 4h 0m, and half of that is the climb. Off-track with Aitken it becomes 4h 24m. On the 25-minute Tranter row it is 4h 15m; mark the ground as rough and the calculator drops to the 30-minute row, giving 5h 0m.

The comparison shows where the time goes. On the flat trail distance is nearly the whole estimate, so pace and surface matter most. On the mountain the ascent term carries as much weight as the distance, the terrain setting adds most of an hour, and the descent, which the calculator ignores, is steep enough to cost more time again.

Naismith ignored descent. Eric Langmuir's Mountaincraft and Leadership adds a correction: on gentle slopes of about 5 to 12 degrees, subtract 10 minutes per 300 m of descent, and on slopes steeper than 12 degrees, add 10 minutes per 300 m. Steep descents are slow because walkers brake with every step. If your route drops a long way on steep ground, add that time by hand, since this calculator does not.

Long days are where the corrections diverge most. A 15-mile route with 4,500 ft of gain is 7h 15m by Naismith. A walker on the 30-minute row who marks the ground as rough is moved to the 40-minute row, and the calculator returns 12h 0m. That row in Tranter's table stops at 7 hours of Naismith time, so the 12-hour figure is an extension of the table's last slope rather than a published value. When a result lands past the end of your row, read it as a sign that the day is too long for that fitness level, which is what the blank cells in the original table meant.

The fitness rows matter more than any other input on a long day. A 5-hour Naismith estimate reads as 2h 45m on the 15-minute row and 8h 30m on the 50-minute row, so the same route can be a morning for one walker and a full day for another.

Every result is a moving-time estimate for walking on hill paths. It does not model scrambling, snow, river crossings, route-finding in poor visibility, altitude, heat or a heavy pack, all of which slow a party well beyond the formula. It is not a safety assessment, and it cannot tell you whether a route is within your ability.

It also ignores descent, as described above, and group pace. A group moves at the speed of its slowest member, so enter that person's fitness, not the strongest walker's. Tranter's fitness test itself is rarely measured precisely; if you have not timed a 1,000 ft climb, the plain Naismith figure plus generous breaks is the more honest plan.

Load changes pace, so size the bag first with the Camping Pack Weight Calculator; a pack well over its body-weight guideline is a good reason to pick a slower Tranter row. To measure the straight-line legs between waypoints before adding up the route, use the Geocaching Distance & Bearing Calculator. If you already know your flat-ground speed from runs or walks, the Pace Calculator converts it to minutes per mile or kilometre so you can compare it with Naismith's 3 mph assumption. For planning time limits underwater rather than on a hill, the scuba diving no-decompression limit calculator reads the published air table for a planned depth and gas mix.