Whether you are a weekend warrior or a seasoned thru-hiker, knowing the physical demands of a trail before you step foot on it is critical for safety and enjoyment. This calculator uses a modified version of the Shenandoah National Park Hiking Difficulty Formula to provide an objective score for any trail.
The Mathematics of the Hike
The core formula used is: Rating = √(2 × Distance × Elevation Gain). We then apply a multiplier based on the terrain type to account for technical difficulty.
Difficulty Score
Category
Description
0 – 50
Easy
Suitable for most fitness levels. Generally flat or very gradual inclines.
50 – 100
Moderate
Steady inclines. Requires basic physical fitness and proper footwear.
100 – 150
Moderately Strenuous
Challenging for most. Significant elevation gain and steeper grades.
150 – 200
Strenuous
Highly demanding. Expect steep climbs and potential fatigue.
Above 200
Very Strenuous
Extremely difficult. Often involves technical terrain and long durations.
Real-World Examples
Example 1 (Casual Day Hike): A 4-mile hike with 400 feet of gain results in a score of 56.5 (Moderate).
Example 2 (Mountain Summit): An 8-mile round trip with 3,000 feet of gain results in a score of 219 (Very Strenuous).
Example 3 (Technical Scramble): A 3-mile hike with 1,500 feet of gain on rocky terrain (1.3 factor) results in a score of 123 (Moderately Strenuous).
Factors That Increase Difficulty
While our calculator covers distance, elevation, and terrain, remember that external factors can significantly change how a hike feels:
Altitude: High-altitude hikes (above 8,000 ft) are significantly harder due to lower oxygen levels.
Weather: High heat, humidity, or freezing temperatures increase physical strain.
Pack Weight: A 30lb backpacking pack increases the effective effort by roughly 20-30%.
Mental Fatigue: Difficult navigation or exposure (cliffs) increases the perceived difficulty.
function calculateHikeDifficulty() {
var distance = parseFloat(document.getElementById("hikeDistance").value);
var elevation = parseFloat(document.getElementById("hikeElevation").value);
var terrain = parseFloat(document.getElementById("hikeTerrain").value);
var resultBox = document.getElementById("hike-result-box");
var scoreDisplay = document.getElementById("resultScore");
var labelDisplay = document.getElementById("resultLabel");
var descDisplay = document.getElementById("resultDesc");
if (isNaN(distance) || isNaN(elevation) || distance <= 0 || elevation < 0) {
alert("Please enter valid positive numbers for distance and elevation gain.");
return;
}
// Formula: Sqrt(2 * distance * elevation) * terrain factor
var rawScore = Math.sqrt(2 * distance * elevation) * terrain;
var finalScore = Math.round(rawScore * 10) / 10;
var category = "";
var cssClass = "";
var description = "";
if (finalScore = 50 && finalScore = 100 && finalScore = 150 && finalScore < 200) {
category = "Strenuous";
cssClass = "category-strenuous";
description = "A challenging hike that requires endurance.";
} else {
category = "Very Strenuous";
cssClass = "category-strenuous";
description = "Extremely difficult. Only for experienced hikers.";
}
scoreDisplay.innerHTML = "Score: " + finalScore;
labelDisplay.innerHTML = category;
labelDisplay.className = "result-label " + cssClass;
descDisplay.innerHTML = description;
resultBox.style.display = "block";
resultBox.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}