Line Equation Calculator
Enter the coordinates of two points on the line.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Slope m = (y₂ − y₁) ÷ (x₂ − x₁)
- Intercept b = y₁ − m × x₁
- Equation: y = mx + b, and for a vertical line x = x₁
For only the slope, use the slope calculator.
Worked example
Points (0, 1) and (2, 5):
- Slope = 4 ÷ 2 = 2, intercept = 1
- Equation: y = 2x + 1
Why your number may differ
Values are rounded to 6 decimal places in the text. Some books write the line as Ax + By = C instead.
Frequently asked questions
How do I find the equation of a line from two points?
Find the slope m = (y₂ − y₁) ÷ (x₂ − x₁), then the intercept b = y₁ − m × x₁. The line is y = mx + b.
What if the line is vertical?
If both points have the same x, the slope is undefined and the equation is x = that value.
What does the slope mean?
How much y changes for each 1 step in x. A positive slope rises to the right, a negative one falls.