Slope between two points — plus intercept, equation, angle and point-slope form.
Enter any two different points. The line through them is worked out instantly.
Slope (m)
—How to use this tool
Type the x and y coordinates of your first point, for example (0, 0).
Type the second point, for example (3, 4). The two points must be different.
The slope, intercept, both equation forms, angle, parallel and perpendicular slopes appear instantly.
Switch on “Show exact fraction” to see the slope as a reduced fraction when both coordinates are whole numbers.
Formula & worked example
Points (0, 0) and (3, 4): rise = 4 − 0 = 4, run = 3 − 0 = 3, so slope m = 4/3 ≈ 1.3333. The y-intercept is 0, the equation is y = 1.3333x, the angle with the x-axis is about 53.13°, and the perpendicular slope is −3/4.
Limitations — read this before you rely on it
This calculator works with straight lines only — it does not fit curves or find the slope of a function at a point (that needs calculus). A vertical line has no defined slope, and very large coordinates may lose a little decimal precision. Results are rounded to 4 decimal places for display.
Frequently asked questions
Subtract the y-values and divide by the difference in x-values: m = (y₂ − y₁) ÷ (x₂ − x₁). Enter the two points and the calculator does it, including the intercept and equation.
The slope-intercept form is y = mx + b, where m is the slope and b is where the line crosses the y-axis. The point-slope form is y − y₁ = m(x − x₁) for a line through a known point.
A positive slope rises left to right; a negative slope falls left to right; a zero slope is a flat horizontal line. A vertical line has no defined slope because you would divide by zero.
Parallel lines share the same slope. A perpendicular line has the negative reciprocal slope: flip the fraction and change the sign. For slope 2, the perpendicular slope is −1/2.
Use the angle form: angle = arctan(m). A slope of 1 makes 45°, a slope of 0 makes 0°, and a vertical line makes 90° with the x-axis.