Highlight data by quartile

Generic formula 

=A1>=QUARTILE(data,quart)

Summary 

To highlight cells by quartile, you can apply conditional formatting with a formula that uses the QUARTILE function.

In the example shown, we are using 4 different conditional formatting rules. Each rule highlights a quartile in the range B4:F11 using the QUARTILE function. The formulas look like this:

=B4>QUARTILE(B4:F11,3)
=B4>=QUARTILE(B4:F11,2)
=B4>=QUARTILE(B4:F11,1)
=B4>=QUARTILE(B4:F11,0)

Note that we are highlighting quartiles in a specific order, starting with quartile 4 and ending with quartile 1.

It's important that the formula be entered relative to the upper left most cell in the data, in this case cell B4.