pcb - adjacent trace capacitance (horizontal)

I find a lot of online tools to calculate the capacitance between two traces (or a trace and a plane) on opposite pcb layers. One such tool can be found here: http://chemandy.com/calculators/rectangular-capacitor-calculator.htm

However, I would like to calculate the capacitance between adjacent traces on the pcb. Something like this:

Has anyone an idea how to do this?

EDIT :
Imagine the following example:

• Two tracks run parallel for 10 mm.



• Each track is 0.2 mm wide.


• The distance between both tracks is also 0.2 mm.


• Copper thickness is about 20 µm.


• Board thickness is 1.6 mm.


• PCB material is standard FR4.


• One track is signal, the other Gnd.


• There are no other tracks in the area, nor any (Gnd-) planes.