Slope Distance Calculator
A tape along the ground over-measures. Sometimes a lot.
Work out Slope Distance. A tape along the ground over-measures. Sometimes a lot. Every rate is an input, not an assertion.
Horizontal distance
99.504 m
100 m along the ground · 9.95 m rise · 10%
A tape pulled along sloping ground measures slope distance, and a map wants horizontal. The correction is negligible on gentle ground and grows fast: 10% grade costs 0.5%, but 50% grade costs over 10% — enough to lose a metre in every ten. Grade, degrees and 1-in-N all describe the same thing and are easy to confuse. A 100% grade is 45°, not vertical, and 1 in 10 is 10% — but a 1-in-10 railway gradient and a 1:10 architectural ramp are the same slope written two ways. Vertical rise and horizontal distance define the slope entirely, so any two of the three quantities give the third. That is the whole calculation, and it works in any direction.
How the Slope Distance Calculator works
Converting between slope, horizontal and vertical distances at any grade, in percent, degrees or 1-in-N, with the tape correction quantified and the back bearing.
Also known as: slope distance to horizontal distance · grade to degrees conversion · tape correction for slope · what does 1 in 10 gradient mean
Frequently asked questions
How do I convert slope distance to horizontal?
Multiply by the cosine of the slope angle. A tape pulled along sloping ground measures slope distance and a map wants horizontal.
How big is the slope correction?
Negligible on gentle ground and fast-growing after that: 10% grade costs 0.5%, 30% grade costs 4%, and 50% grade costs over 10% — a metre in every ten.
Is 100% grade vertical?
No, it is 45°. Grade is rise over run as a percentage, so 100% means rising as much as you travel forward. Vertical is an infinite grade.
What does 1 in 10 mean?
One unit of rise for ten of horizontal run — the same as a 10% grade. Railway gradients and architectural ramps both use it, written as 1 in N or 1:N.
Which two measurements do I need?
Any two of slope distance, horizontal distance and vertical rise define the third, along with the angle. This page works from whichever pair you have.
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