Point-slope form calculator
Enter the slope m and a point on the line to get its equation, ready to copy.
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How to use it
- Enter slope m, x1 and y1.
- 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
Point-slope form: y - y1 = m(x - x1). Simplified: y = mx + b with b = y1 - m·x1, and the x-intercept is -b/m when m ≠ 0.
Example
Inputs: Slope m = 2, x1 = 1, y1 = 5. Result: Slope-intercept form: y = 2x + 3; Y-intercept b: 3; X-intercept: -1.5.
Limits and caveats
- Cannot represent a vertical line, whose slope is undefined; its equation is simply x = x1.
- Long decimals are rounded.
Questions about this tool
When do I use point-slope form?
When you know the slope and one point on the line. It is the quickest way to write the equation.
How do I convert it to y = mx + b?
Distribute m over the bracket and move y1 to the right: b = y1 - m·x1.
What if the slope is a fraction like 2/3?
Enter it as a decimal with enough digits, such as 0.6666666667.