Calculating number of Squares for a Quilt
 

I am trying to determine the number of charm packs I need to make a quilt for my bed; to do this, I need to determine the number of 5" squares needed. I found a guide to doing this, and this is the result I came up with. My question is: Does this make sense -is it correct? This is how I did the math:
The width of my mattress, which includes the 17: drop on the sides of the mattress):
71" /4.5" (allowing for seam take up)= 15.77=16 (rounded up)
The length of my mattress, which incudes the 17: drop:
109/4.5 (allowing for seam take up)=24.22=25 (rounded up)
So, 16 X 25 = 400 -5" squares
The charm pack I am buying has 40 5: squares, so I need 10 charm packs to cover my 71: X 109" (including drops) quilt.

Does this look right? Did I mention that I HATE math? Oh, well... Thanks for any advice you may offer!

Makes sense to me, but I'm no mathemagician. Wait for someone else to chime in.

Watson
PS...I just designed it in EQ8 and that's what it worked out to.

Good numbers - your math / logic is spot on

I'm guessing you're fitting to a full size mattress that is typically 54" x 75". If so, your end result of 400 5" squares appears accurate. However, I think your width should be 88" (54+17+17) and your length should be 92 (75+17). Again, the end result of 400 5" charm squares is the same. If you were to make a top at 71" x 109" it would be a very narrow and long quilt.

Lastly, I never seem to like all of the fabrics in a pre-cut pack so I would opt for at least 1-2 more packs of 40 to allow for a bit of choice.

Hope that's helpful! Can't wait to see what fabrics/pattern you select!

Christine

Can't do the math but, I would recommend purchasing an extra yard in your favorite print in the line. I agree with Christine (TheMerklyFamily) there always seems to be one or two that don't fit in the line. This way, your favorite color or pattern will be there.

Don't forget to account for shrinkage for quilting and washing/drying.