How to find the slope between two points
- Enter the first point (x₁, y₁) and the second point (x₂, y₂).
- Read the slope m = (y₂ − y₁) ÷ (x₂ − x₁), as a decimal and a fraction when it is one.
- Read the equation y = mx + b, both intercepts, the angle of the line and the distance between the points.
Slope as a grade or angle
Roads and ramps often give slope as a percent grade: rise ÷ run × 100. A slope of 0.08 is an 8% grade, about 4.6°. The calculator shows the angle with the x-axis, which is the arctangent of the slope.
Parallel and perpendicular lines
Parallel lines have the same slope. Perpendicular lines have slopes that multiply to −1: a line with slope 3 is perpendicular to one with slope −1/3.