Slope Calculator

The Slope Formula

m = (y₂ − y₁) / (x₂ − x₁) = rise / run

Slope measures how steep a line is — it tells you how much y changes for every unit change in x.

Rise is the vertical change: y₂ − y₁. Positive rise means the line goes up; negative means down.

Run is the horizontal change: x₂ − x₁. Positive run means moving right; negative means moving left.

The slope is always expressed as rise ÷ run. A slope of 2 means "go up 2 for every 1 unit to the right." A slope of −½ means "go down 1 for every 2 units to the right."

The order of the points matters for the sign of rise and run, but not for the final slope value — you always get the same m either way.

The Four Types of Slope

Every slope falls into one of four categories:

Positive slope — line rises from left to right (m > 0). Steeper line = larger m.
Negative slope — line falls from left to right (m < 0). The more negative, the steeper the fall.
Zero slope — perfectly horizontal line (m = 0). y stays the same as x changes.
Undefined slope — perfectly vertical line (run = 0). x never changes, so the ratio is undefined.

Horizontal lines have slope 0. Vertical lines have no slope (undefined) — not 0!

Slope still feels slippery?