I am preparing to lay a mixed media floor on a plywood base that will be built from sandstone tile 15.75" x 15.75" bordered with a 5.5" oak hardwood border between each tile. The three rooms, foyer and two hallways I am going to make this installation in all adjoin and equal approx. 1355 square feet. Can someone provide a formula for calculating the total number of tiles and running board feet of hardwood I will need. Also, I am laying this pattern on a 45 degree diagonal with respect to the rooms which of course are all square with each other. There will not be any "breaks" between the rooms or hallways.

Yes, Ken here has some info on it and believe theres some calculators out there if you google it.

http://www.hardwoodinstaller.com/instal ... -media.htm

Have you thought out the details like: is there going to be a continuous border one plank wide around perimeter of rooms and through doorways, you will want to have full length/ no butt-joints between corners of the pattern between tiles in the wood planks. You already know that you will need to have extra tiles and planks.
Find out how much tile is in a box and how much a bundle of flooring or how to order the custom length planks. You may make your own with stock plank if you are a little short, to finish the job.
You may need to return extra boxes of tiles if possible, with a re-stocking fee and can always cut a few more planks for the border/field joint pattern.

Calculators? That would be nice. I've only installed these grid types of designs, never have bid on one. Maybe some CAD program, or plain ole graph paper?

thanks Ken and Pete for the info and guidance. I finally drew up the design on graph paper and came up with some estimates. I now have a new question. My plan now is to frame with 5.5 oak boards, four 12x12 sandstone tiles on a diagonal to the room. Im sure I will need to grout the 12x12 tiles, but should I also grout where the tiles meet wood? Im doing this to reduce the amount of wood.

Here's another old thread posted here in 2009.

mixed-media-installation-thoughts-and-opinions-t7452.html

I think that the grout next to the wood should be one half the width of the caulking between the tiles. Be sure to ease the edge of the wood planks so the finish can coat the edge on the plank before it is grouted/caulked.
There is a company that makes sanded caulking which will match the color of your grout and be about the same surface texture.. I recommend a backer rod be installed into the gap between the tile and the wood. Then the grout/sanded caulking will cure like it is supposed to as it will be only about a quarter inch thick.
Grout the tiles after the backer rod is installed, but only inside of the backer rod perimeter. The sanded caulking will shrink some.
Gluing the plank down well will help stiffen the subfloor and can reduce cracking between tiles and grout. I like the new sausage tubes.