Slope and line equation from two points
Enter the coordinates of two points to get the slope and line equation. Vertical lines are handled too.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter x1, y1, x2 and y2.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Slope m = (y2 - y1) / (x2 - x1), y-intercept b = y1 - m·x1, angle θ = arctan(m). If x1 = x2 the line is vertical, x = x1, with undefined slope.
Example
Inputs: x1 = 1, y1 = 2, x2 = 3, y2 = 8. Result: Slope m: 3; Y-intercept b: -1; Angle of inclination: 71.5651 °.
Limits and caveats
- The angle is measured from the positive x axis, between -90 and 90 degrees.
- Long decimals are rounded in the equation.
Questions about this tool
What does a negative slope mean?
The line falls as you move right: y decreases as x increases.
Why is a vertical line's slope undefined?
Because x2 - x1 is zero and division by zero is undefined.
Does the order of the points matter?
No. Swapping the points gives the same slope and equation.