Trail Grade Calculator
Percent grade, angle, and ratio from rise and run for any trail.
What it does
Trail grade tells how steep a climb really is. It divides vertical rise by horizontal run, so a short wall and a long ramp get numbers you can compare. Hikers use it to pace effort, builders use it to set switchbacks.
The tool above takes rise and run and returns three views: percent grade, angle in degrees, and a ratio like 1 in 12.5. Metric and imperial modes share the same math; only the units change.
USGS teaching pages define percent slope exactly this way: rise divided by run times 100. Forest Service trail guides use the same form when they cap grades for accessible routes and drainage. Because the formula is standard, numbers transfer between maps, signs, and crew notes.
Grade shapes decisions. Under 5 % most walkers cruise. Near 8 to 10 % climbs feel steady and slow groups down. Past 15 % footing, water runoff, and fatigue all demand care, which is why builders stretch the run with traverses instead of pushing straight up.
How to use
- Pick metric (meters) or imperial (feet).
- Enter vertical rise from a map, sign, or GPS track summary.
- Enter horizontal run, not slope distance.
- Read percent grade, angle in degrees, and the 1 in X ratio.
- Use the steepest pitch for safety calls and the full route average for pacing.
- Compare with the table to rate the climb.
Formula
- rise
- Vertical climb in meters or feet.
- run
- Horizontal map distance in the same units.
- arctan
- Inverse tangent result, shown in degrees.
Rise and run must share units (meters with meters, feet with feet). Run is horizontal map distance. Ratio form is 1 in (run / rise), which builders read directly on site.
Worked example
Example: 120 m rise over 1500 m run
A trail climbs 120 m over 1500 m of horizontal map distance.
- Divide rise by run: 120 / 1500 = 0.08.
- Percent: 0.08 x 100 = 8.0 %.
- Angle: inverse tangent of 0.08 = 4.57 deg.
- Ratio: 1500 / 120 = 12.5, so 1 in 12.5.
- Read: a steady 8.0 % climb, moderate for a maintained trail.
Reference table
| Grade | Angle | Feel |
|---|---|---|
| Under 5 % | Under 2.9 deg | Easy cruise for most walkers |
| 5 to 8 % | 2.9 to 4.6 deg | Steady climb, pace drops |
| 8 to 12 % | 4.6 to 6.8 deg | Hard push, rests help |
| 12 to 20 % | 6.8 to 11.3 deg | Very steep, traction matters |
| Over 20 % | Over 11.3 deg | Scramble zone for many |
Limits
- Needs true horizontal run. Slope distance inflates the base and flattens the answer.
- GPS noise can swing short climbs by a point or more.
- One average hides steep pitches inside a long route.
- Snow, mud, and loose rock change effort at the same grade.
Common mistakes
- Dividing by walking distance instead of map run.
- Mixing feet of rise with meters of run.
- Reading 45 % as 45 degrees (45 degrees is 100 %).
- Averaging a whole hike and missing a harsh pitch.
- Trusting a single GPS spike for the rise.
Try it yourself
Quick checks. Answers sit tucked under each question.
Grade for 60 m rise over 800 m run?
60 / 800 = 0.075, so 7.5 %. Angle is 4.29 deg and ratio is 1 in 13.3.
Grade for 200 ft rise over 2600 ft run?
200 / 2600 = 0.0769, so 7.7 %. Angle is 4.40 deg and ratio is 1 in 13.
Questions
What is the difference between percent grade and angle?
Percent grade is rise over run times 100. Angle is the inverse tangent of the same fraction. A 100 % grade equals 45 degrees, and grades above 100 % are steeper than 45 degrees.
Can I use phone GPS elevation for rise?
Yes. Phone GPS mixes horizontal and slope distance and adds noise. For short climbs, read rise from contours or a barometric log and measure run on a map for a cleaner number.
Is run the same as walking distance?
No. Run is the horizontal map distance, not the distance your feet travel up the slope. On steep ground the walking distance runs longer than the run, which is why grades can pass 100 %.
Which grade matters for trail building?
Use the steepest sustained pitch, not the whole route average. Design guides cap accessible trail segments near 5 % to 8 % depending on length, with short ramps allowed higher.
What grade feels steep on foot?
Roughly 20 %. Anything above about 15 % feels steep to most walkers, and above 30 % most people scramble. Switchbacks cut the grade by stretching the run.
Why show a ratio like 1 in 12.5?
The ratio form suits builders: 1 in 12 is one unit up per 12 along. Percent suits signs and maps. The tool prints both so crews and hikers stay in sync.
Sources
- USGS: percent of slope and angle of slope
- US Forest Service trail construction notebook
- American Trails: measuring trail grade