Below are some some instructions for you to figure out the amounts of hexagons and triangles you will need for a specified size quilt. 

Twin quilt: 64" x 99" (based on standard twin mattress size of 39" x 75" with a 12" drop")

Twin Center Panel: 40" x 75"

Some division required here...get out the calculator...

If you use a 3" hexagon, you want to divide the width of the center panel above, by 3". You get 13.3 hexagons across (round it down to 13 or up to 14). And for the length, you divide 75" by 3" and you get 25 hexagons down.

So how many do you need altogether then? multiply 14 across times 25 down and that gives you 350 hexagons all together. For the sides that have different amouts of triangles, you will need 25 down each side so pull out 50 (25 x 2) for the side hexagons that require different amounts of triangles, and sew the rest "normally".

How many triangles will you need? Take the amount of hexagons times 2. If you have 350 hexagons, then you need 700 triangles. But the ends are different you say? Yes, but some side hexagons take one triangle and some take three so it all evens out in the end. That seems like a lot to cut but you can quick cut them really really fast! 

Let's try a four inch hexagon on a twin size quilt....If you use a 4" hexagon, it will go ten times into 40, which is easy, so you will need 10 hexagons across. For the length, you need 18.75 hexagons (round it up to 19 or 20 hexagon's).

You will need 200 hexagons and 400 triangles. If you use 20 hexagons down each side, pull out 40 for the side hexagons that are different.

Now you are on your own...

Full quilt: 79" x 99" (based on standard full/double mattress size of 54" x 75"and 12" drop on all four sides)

Center Panel: 54" x 75"

Queen quilt: 84" x 104" (based on standard queen mattress size of 60" x 80" and 12" drop on all four sides)

Center Panel: 60" x 80" finished)

King Quilt: 96" x 108" (based on standard king mattress size of 72" x 84" and 12" drop on all four sides)

Center Panel: 72" x 84"

Crib Quilt: Varies...

Center Panel: 27" x 50"

You may not want 12" drops on a crib quilt, so adjust borders to your liking.

Cot or sofa cuddle quilt: 54" x 99" based on cot mattress size of 30" x 75" and 12" drop on all four sides)

Center panel: 30" x 75"

Here again, you may not want a 12 inch drop on this quilt, so adjust borders to your liking.