About Perpendicular Line Calculator
This perpendicular line calculator finds the negative reciprocal slope of a given line and writes the equation of the line with that slope through your point. The parallel line through the same point is shown too. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
The page opens on the line through (-3, 2) and (3, 5), slope 0.5, and the point (4, -1). The perpendicular slope is -2.
How to use Perpendicular Line Calculator
- Type the coordinates of point 1 and point 2. Negative numbers and decimals are fine.
- Pick what you need: everything, slope and angle, line equation, distance, midpoint, or parallel and perpendicular lines.
- Read the headline answer and the table of every result under it.
- Check the graph. Drag to pan and scroll or pinch to zoom, and use the trace to read coordinates.
- Open the step-by-step working to copy the method into your homework.
- For parallel and perpendicular lines, enter the point the new lines must pass through.
Features
- Slope as an exact fraction and a decimal, with rise and run.
- Angle of inclination between 0 and 180 degrees.
- Slope-intercept, point-slope and standard form with whole-number coefficients.
- Vertical and horizontal lines handled correctly (slope undefined or zero).
- Distance formula and midpoint formula with steps.
- Parallel and perpendicular lines through a chosen point.
- An interactive graph of the line, the points and the midpoint.
- Step-by-step working in KaTeX.
Perpendicular slope
The product of perpendicular slopes is minus one.
m₁ · m₂ = −1Worked examples
Line (-3, 2), (3, 5); point (4, -1) gives Slope -2
Negative reciprocal of 1/2.
Privacy: how it works
- Every result is calculated by code in your browser tab. The coordinates you enter are not sent to Ulkaa or to any other server, and there is nothing to sign in to.
Tips
- Keep the order consistent. Subtract the first point from the second in both the numerator and the denominator, or the sign of the slope flips.
- If both points are the same, no line is defined. The calculator tells you.
- Two lines are perpendicular when the product of their slopes is −1, and parallel when the slopes are equal.
- Standard form is scaled to whole numbers with no common factor, so decimals in the points are cleared for you.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your points are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your points are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
How do I find a perpendicular line?
Flip the slope and change its sign, then use your point in point-slope form.
Can a vertical line be perpendicular to a horizontal one?
Yes. A horizontal line has slope 0 and its perpendicular is vertical, with undefined slope.
More Slope Calculator pages
- Slope CalculatorEnter two points to get the slope, the angle, the equation of the line, the distance and the midpoint, with the working and a graph.
- Slope From Two Points CalculatorEnter two points and get rise over run and the angle of the line.
- Distance Formula CalculatorEnter two points to get the straight-line distance between them.
- Midpoint CalculatorEnter two endpoints to get the midpoint of the segment.
- Line Equation From Two PointsEnter two points to get the equation of the line in three forms.
- Slope-Intercept Form CalculatorEnter two points and read the slope and the y-intercept of y = mx + b.
- Parallel and Perpendicular Line CalculatorEnter a line by two points and a third point, and get the parallel and perpendicular lines through it.