Perpendicular line calculator

Find a line perpendicular to a given line passing through a point. If original slope is m, perpendicular slope is −1/m.

Perpendicular to slope m =
Through point (x, y)

Perpendicular slopes

If one line has slope m, a perpendicular line has slope −1/m. The slopes multiply to −1.

Perpendicular to slope 2 through (1,3): new slope = −1/2. y − 3 = −½(x − 1) → y = −x/2 + 7/2.

Popular slope & distance problems
(1,2) and (4,8) (0,0) and (5,5)
Related calculators
Parallel line Slope Point-slope form