Given a slope and one point on a line, find the missing x or y coordinate of another point with the Find Missing Coordinate Calculator. Results update as you type.
Find missing coordinate calculator
Using the find missing coordinate calculator
This calculator solves for a missing x or y value when you know the slope and a point on the line:
Find X: Enter a known point, slope, and your target Y value. The calculator finds the X coordinate that produces that Y value on the line.
Find Y: Enter a known point, slope, and your target X value. The calculator finds the Y coordinate at that X position.
The calculator also shows the line equation, y-intercept, and distance from your known point to the new point.
How it works
The calculation uses the slope-intercept form of a line (y = mx + b). First, it finds b using your known point:
b = y_1 - m \cdot x_1
Then it solves for the missing coordinate:
- Find X: x = (y - b) / m
- Find Y: y = mx + b
Example
A line passes through (2, 3) with slope 4. Find the x-coordinate where y = 15:
First find b: b = 3 - 4(2) = -5
Then solve: x = (15 - (-5)) / 4 = 20 / 4 = 5
The point (5, 15) is on the line.
