How do you calculate slope from two points?

Subtract the first y value from the second y value to get rise, then subtract the first x value from the second x value to get run. Divide rise by run. For points (1, 2) and (5, 10), rise is 8 and run is 4, so the slope is 2.

What does undefined slope mean?

Undefined slope means the horizontal change is zero, so the formula would divide by zero. This happens when both points have the same x coordinate but different y coordinates. The line is vertical, written as x equals a constant, and it cannot be represented by y = mx + b.

What if both coordinate points are exactly the same?

If both points are the same, there is no unique line determined by the pair. Rise and run are both zero, so the slope formula becomes 0 divided by 0, which is undefined. The calculator labels this as the same-point case rather than treating it as a vertical line.

How is the y-intercept calculated from slope?

For a non-vertical line, use y = mx + b and substitute one known point. Rearranging gives b = y1 - m x1. Once b is known, the line can be written in slope-intercept form. The calculator shows this form when the slope is defined.

Can the slope be negative or zero?

Yes. A negative slope means the line falls as x increases. A slope of zero means the line is horizontal, because the y values do not change. A positive slope means the line rises as x increases. The sign comes directly from the direction of rise compared with run.

Coordinate Geometry

Slope Calculator

Find slope from two coordinate points, including rise, run, y-intercept, point-slope form, slope-intercept form, and vertical-line status.

Formula

(y2 - y1) / (x2 - x1)

Outputs

Slope + Line Forms

Special Case

Vertical Lines

No sign-upFormula shownPrint-friendly

Live calculator

Slope from two points

Slope

Rise

Run

Y-intercept

Line forms

Point-slope form

y - 2 = 2(x - 1)

Slope-intercept form

y = 2x

What Can You Create?

Turn two points into slope and line forms

Slope value

Calculate the rate of change between two coordinate points using rise over run.

Line equations

Convert the two-point result into point-slope and slope-intercept form when possible.

Vertical-line status

Detect undefined slope when x values match instead of forcing an invalid denominator.

Formula

Slope formulas used on this page

Slope measures vertical change divided by horizontal change. When the horizontal change is zero, the slope is undefined.

Working formulas

Slope from two points

m = (y2 - y1) / (x2 - x1)

Subtract y values for rise and x values for run, then divide rise by run.

Y-intercept

b = y1 - m x1

Use one point and the slope to solve for the intercept in y = mx + b.

Slope-intercept form

y = mx + b

This line form is available when the line is not vertical.

Symbols

m - slope: The rate of change from one point to the other.
rise - vertical change: The difference y2 - y1 between the two y coordinates.
run - horizontal change: The difference x2 - x1 between the two x coordinates.
b - y-intercept: The value where a non-vertical line crosses the y-axis.

Why Users Love This Tool

Slope results that explain the line, not only the fraction

Geometry-ready outputs

Rise and run are shown separately so users can see where the slope value comes from.
The result panel includes y-intercept, point-slope form, and slope-intercept form for graphing workflows.
Vertical and same-point cases are labeled clearly because their line behavior is different.
Copy and print controls make the result usable in notes, worksheets, and tutoring sessions.

Learning context

Formula notes connect slope to rate of change and coordinate geometry.
Related links point users to linear equations, midpoint, distance, and the slope guide.
FAQ answers explain undefined slope, y-intercept, point-slope form, and repeated points.
The page supports graphing and algebra lessons without requiring a full graphing calculator.

Perfect For

Slope support for graphing, algebra, and coordinate work

Students

Check slope homework and understand why vertical lines have undefined slope.

Teachers

Create two-point examples with slope, intercept, and line forms visible together.

Technical plotting

Use rise and run as a fast coordinate check before drawing or reviewing a line.

How It Works

How it works in three quick steps.

Enter the first point

Add x1 and y1 from the first coordinate point.

Enter the second point

Add x2 and y2 so the calculator can compare the vertical and horizontal change.

Read the slope and line forms

Use the rise, run, slope, y-intercept, and line-form outputs to check graphing work.

Download & Print

Save or print a slope result

Copy the line summary

Copy coordinates, rise, run, slope, intercept, and line form in one readable statement.

Print the calculation

Print the calculator state, formulas, FAQ content, and related tools for study use.

Compare point pairs

Reset or adjust coordinates to compare positive, negative, zero, and undefined slopes.

About This Tool

Why slope calculations need context

Slope is one of the first places where algebra and coordinate geometry meet. A user may ask for slope, but the useful answer often includes more than a single number. Rise and run show how the value was produced, the y-intercept connects the result to y = mx + b, and point-slope form helps users write the equation directly from one point and the slope. Toolarithm's Slope Calculator keeps those related outputs together so students can move from a pair of points to graphing language without re-entering the same information.

The calculator also handles edge cases that matter in real coursework. Vertical lines do not have a defined slope because the run is zero. Identical points do not define a unique line. Returning a numeric answer for either case would be misleading, so the page labels the status and explains it in the FAQ. The related equation, midpoint, distance, and slope-guide links help users reuse the same coordinates across the formulas that normally appear together in graphing lessons.

Keep building

Explore more math tools

Math calculators