Quick answer

ratio = rise / run; % = ratio x 100

Formula

  • rise/run
  • % = (rise/run) x 100
  • angle = arctan(rise/run)

Introduction

Our Slope Percentage Calculator is a rise-over-run calculator that also shows percent and angle together.

Definitions: what is slope percentage. Formula sheet: slope percentage formula.

Surveyors, engineers, and mappers use the same words with different instruments; this article aligns vocabulary.

Rise and run in the field

Horizontal vs vertical measurements must come from perpendicular axes. Mixing plan north with a profile vertical without labeling causes confusion.

Engineering sections show rise clearly; map distance provides run when stations align.

GIS slope layers estimate rise between cells and divide by cell size as run. Resolution affects the percent you read.

Mapping examples include watershed grades, trail profiles, and parking lot cross slopes.

Formula and relationships

  • rise/run
  • % = (rise/run)x100

How-to sequence: how to calculate slope percentage.

Road grade angle: grade percentage calculator.

Examples: slope percentage examples.

Step-by-step guide

  1. Measure vertical rise. Level loop, laser, or DEM difference.
  2. Measure horizontal run. Tape, stationing, or map scale.
  3. Form the ratio. rise divided by run with sign.
  4. Scale to percent. Multiply by 100 for reports.
  5. Optional angle. arctan(rise/run).

Survey snippet

Rise 1.8 m, run 24 m: ratio 0.075, percent 7.5%, angle about 4.29 degrees.

Batch many stations in slope percentage in Excel.