Im building a frag tank thats 60x24x14
i want to build it out of 3/8" glass but it would cost $250 compared to 1/4 that could cost me $120.

is it ok to build a rimless frag tank this big with 1/4" glass?

NO. it will blow apart.

how thick of glass do i need?

bump?

You're looking to build an essentially 75 gallon frag tank. If you eurobrace the top I would expect 3/8" to cut it, but I would seriously doubt 1/4" would work at all. 3/8" is a standard thickness for a 75G, but if you take out the bracing all together I wouldn't go less than 1/2" and would make doubly sure I could make a real nice seam and had a good base to put it on.

cut the height to 8 or 9 inches, or 6 if it is sps frags. That would help with the cost and amount of pressure on the glass, add a couple of braces maybe. Just ideas maybe they can help,

alrite thanks guys. any more ideas? im open. i just want to keep it as cheap as possible

The thickness of the glass required depends almost entirely on the depth of the tank, not on the total volume of the tank. There are only two forces that matter: the water pressure at the bottom of the tank (which depends solely on depth), and the amount of bowing the glass is allowed to do. Thick glass can go longer distances (side to side) without bowing, but 1/4" glass should easily be able to go 30" without bowing much, so put a horizontal brace at the top of your tank, in the middle, connecting one 60" side to the other. Make the brace 5" wide or so. Euro-bracing would also be sufficient to limit bowing, but I wonder if the 60" long bracing pieces should be made of thicker glass (??).
As for the pressure, look around at other tanks, and see how deep tanks built with 1/4" glass are. Regardless of length and width, you can use 1/4" glass to make a tank as deep as any other tank made with 1/4" glass (assuming you limit bowing as described above). If your tank will be rimless, only use rimless 1/4" tanks as a guide. Again, the number of gallons the tank will hold is unrelated to the thickness of the glass needed.

could i do 3/8 sides with a 1/4 bottom?

my 29g is 1/4" and its 18" high but its got a rim.

so what if i do like 10'' high just eurobraced?

What is it you are planning on cultivating, and yes at 10 inches you would be ok. I would still however suggest even shallower. If you want SPS I would suggest a 7 inch depth or less, you could light the whole tank with 2 halides, the bigger the better, if you are doing LPS or Softies two 150s or 1 250 with some actinics would be fine. And even though it looks funny just run bare bottom.

ya i was planning on running bare bottom. but can you put frags on racks to they are closer to the surface? also i found a 100g acrylic tank for $50 so i think i might buy that and cut off most the topp with a table saw. so it will be like 60x18x8-10"