Slope Calculator

Two points, zero stress — get the slope, the line equation and the angle in one shot.

Point 1: (, )

Point 2: (, )

What slope actually tells you

Slope is the steepness of a line — how much it rises (or falls) for every step you take to the right. This tool takes two points, (x¹, y¹) and (x², y²), and works out the slope using rise over run: m = (y² − y¹) ÷ (x² − x¹). A positive slope climbs left to right, a negative one drops, zero is a flat horizontal line, and a vertical line has an undefined slope because the run is zero (you can't divide by it).

When you'd use it

Algebra and geometry homework is the obvious one, but slope shows up well beyond the classroom. Builders and DIYers use it to check a wheelchair ramp meets the 1:12 rule, roofers describe pitch as rise over run, and hikers read grade as a percentage. If you have two data points — say cost at two order sizes, or distance at two times — the slope is the rate of change between them, and the y-intercept is where the line would cross at x = 0.

A quick example

Take (2, 3) and (6, 11). The rise is 11 − 3 = 8, the run is 6 − 2 = 4, so the slope is 8 ÷ 4 = 2. Plugging back in gives the equation y = 2x − 1, and the angle of the line is about 63.4° from horizontal. This tool shows all four results at once so you can check your own working.

How to use it

Enter the coordinates of your first point in the x¹ and y¹ boxes.
Enter the second point in the x² and y² boxes. Negative numbers and decimals are fine.
Read off the slope, the y-intercept, the full line equation (y = mx + b), and the angle in degrees.
Change any value to recalculate instantly — handy for testing a few point pairs in a row.

FAQ

What does an "undefined" slope mean?: Both points share the same x value, so the line is vertical and the run is zero. You can't divide by zero, so slope is undefined rather than a number.
How do I turn slope into a percentage grade?: Multiply the slope by 100. A slope of 0.08 is an 8% grade — the same figure you'd see on a steep road sign.
Does the order of the two points matter?: No. As long as you subtract the y values and x values in the same order, you get the same slope either way.
Is it free, and does anything get uploaded?: It's completely free, supported by ads, and runs entirely in your browser — your numbers never leave your device.