Flooring Tile - When running tile on a 45 deg, what percentage more should one buy?

I'm sure it also has to do with how many walls there are too. What would my starting point be?

Also, how do you lay out a floor at 45 degs? Meaning where do you start? Do you just go 45 degs off of a wall and branch out from there?

To layout at 45 degrees in a small room I just measure off the most visible and important wall in two places snap a line put the corners on the line and voilla instantaneous 45. assuming the tiles are square and the walls are straight and square. I think a little more info is needed like size of room big or small, entry ways, obstructions. Just did a google of how to layout tile and there are plenty of pictures in a lot of sites. I don't know if I can post one here but http://floorstransformed.com/patternfloor.html looks good

Excellent link!

Better yet, go to http://www.legendlakesmchenry.com/

Then click on "Residences" Then scroll down to the Country Towns

Once in there, look for MOONSTONE. Then click "Floor Plan"

Believe it or not, the amount of wastage is the same whether the tile is laid parallel or at an angle to the walls. This can be proven mathematically (assuming trimming is required along each wall, which is almost a certainty), even though tilers may claim otherwise in practice.

So your calculation will depend upon the size of the tile and the room, not the orientation of the tile.

While it can be proven mathematically for square footage actuallity,it cannot be proven for lineal footage of factory edge.Install a quarter million feet + on the diagonal then come back and tell me I'm wrong.The reason tilesetters tell you it takes more is because IT TAKES MORE!!!

A good rule to follow is 5% for square rooms and 10% for the diagonal rooms.After you get the square lines and check them for square,the 3,4,5 method,then make a little box starting at the point where the 2 lines intersect go say 2 foot down the line one way then 2 foot down the line the other way then go out from that point where you put that mark and at 2 feet put another mark,then go back to the other side and come out 2 feet from that mark and where those marks cross and the lines cross from the original 2 lines is you're 45 degree angle, make any sense?