I'm wanting to purchase a new seatpost and am looking at the fizik cyrano r1

Wiggle | Fizik Cyrano R1 Carbon Seat Post | Seat Posts

I've looked at the specs for my bike and the current seatpost has a size of 27.2mmx300mm. The fizik doesn't have a size that matches this completely. Does this mean it won't fit my bike?

Uh, what IS the size of the Fizik? Is this a guessing game? You have to match the diameter. The length doesn't have to match as long as you still have the minimum insertion. If you have more than the minimum inside your seat tube now , that excess is how much shorter the new post can be--assuming the saddle will mount at the same height on both posts. Longer is usually no problem.

The 27.2/330 should work fine.

A quick look at the link will show the available sizes for the seatpost.

To the OP: the indicated size of the seatpost gives two dimensions - the first one (27.2 mm) is the seatpost diameter, and the second (300 mm) is the length of the post from the bottom to the rails.

If your current seatpost's "minimum insertion" line is substantially below the seat tube collar then I would guess the 270 mm length would not be a problem. Going longer than 300 mm is better, albeit with weight penalty if you're a WW.