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Slope Calculator
Find the slope of a line that passes through two points, along with its equation and angle.
About the Slope Calculator
Find the slope of a line that passes through two points, along with its equation and angle.
How to use the Slope Calculator
- Enter the coordinates X1, Y1, X2 and Y2.
- Press Calculate.
Formula and method
m = (y₂ − y₁) ÷ (x₂ − x₁)
The line equation is y = mx + b, where b = y₁ − m × x₁.
Worked example
Through (1, 2) and (4, 8): m = (8 − 2) ÷ (4 − 1) = 2, so y = 2x.
Two points. Between (2, 3) and (6, 11) the slope is (11 − 3) ÷ (6 − 2) = 2. The line rises 2 units for every 1 unit to the right.
When to use the Slope Calculator
- Finding the steepness of a line from two points.
- Working out a road grade or a roof pitch.
- Writing the equation of a line.
Common mistakes to avoid
- Subtracting the coordinates in a different order for the top and the bottom.
- Forgetting that a vertical line has an undefined slope.
Tips
- If x₁ equals x₂ the line is vertical and the slope is undefined.
- A positive slope rises left to right; a negative slope falls.
Frequently asked questions
What does slope mean?
It measures steepness: how much y changes for each one unit change in x.
What does a negative slope mean?
The line falls as you move to the right.
What is the slope of a horizontal line?
Zero.