The Lesson

The y-coordinate is the second number in the pair of numbers used to describe Cartesian coordinates. For example, in the Cartesian coordinates (2, 4), the y-coordinate is 4 (the number on the right):

What Does the Y-Coordinate Mean?

The y-coordinate tells you how far up (or down) the vertical y-axis a point is on a graph (measured from the origin). If a point has Cartesian coordinates (2, 4), the point would be 4 units up the y-axis. The image below shows what we mean by a point being 4 units along the x-axis (measured from the origin):

Note: The y-axis is labelled with numbers (0, 1, 2, 3...) so you can measure how far up the point is.

The Y-Coordinate Can Be Positive...

If you go up the y-axis (above the x-axis), it is labelled with positive numbers (0, 1, 2, 3...). The y-coordinate of any point above the x-axis is positive. Imagine a point had an y-coordinate of 4. It would be 4 units above the y-axis:

...Or the Y-Coordinate Can Be Negative

If you go down the y-axis (below the x-axis), it is labelled with negative numbers (0, −1, −2, −3...). The y-coordinate of any point below the x-axis is negative. Imagine a point had an y-coordinate of -4. It would be 4 units below the x-axis:

Which Axis Is Which?

The x is a cross - so the x-axis goes across! The y-axis must go up.