Slope Calculator

Calculate slope from two points, find line equations, and explore parallel and perpendicular lines with interactive graphing.

Two Points Mode

Point 1 (x1, y1)
Point 2 (x2, y2)
Enter two points to calculate the slope of the line passing through them
Known Point (x, y)
Enter a point and slope to get the line equation
Enter slope and y-intercept for y = mx + b form
Enter the slope of the original line
Through Point (optional)
Optional: specify a point for the parallel/perpendicular lines to pass through
x y
Invalid input: Please check your values.

Slope

Slope (m) --
As Fraction --
Type --

Rise & Run

Rise (delta y) --
Run (delta x) --
Angle --

Line Equation

Y-intercept (b) --
X-intercept --

Related Slopes

Parallel --
Perpendicular --
Line Equation y = mx + b

Slope Formulas Reference

Slope from Two Points

m = (y2 - y1) / (x2 - x1)
Rise over run - the change in y divided by the change in x

Slope-Intercept Form

y = mx + b
m is the slope, b is the y-intercept

Point-Slope Form

y - y1 = m(x - x1)
Given a point (x1, y1) and slope m

Parallel Lines

m1 = m2
Parallel lines have the same slope

Perpendicular Lines

m1 * m2 = -1
Perpendicular slopes are negative reciprocals

Angle of Inclination

theta = arctan(m)
The angle the line makes with the positive x-axis

Frequently Asked Questions

How do you calculate slope from two points?

Slope (m) is calculated using the formula m = (y2 - y1) / (x2 - x1), also known as 'rise over run'. Enter the coordinates of two points and this calculator will compute the slope instantly.

What is slope-intercept form?

Slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept (where the line crosses the y-axis). This form makes it easy to graph a line and understand its behavior.

How do parallel and perpendicular slopes relate?

Parallel lines have the same slope. Perpendicular lines have slopes that are negative reciprocals of each other - their product equals -1. For example, if one line has slope 2, a perpendicular line has slope -1/2.

What does the angle of inclination mean?

The angle of inclination is the angle a line makes with the positive x-axis, measured counterclockwise. It ranges from 0 to 180 degrees. A horizontal line has 0 degrees, and slope = tan(angle).