ration of Bobbin thread to Quilting thread
 

I found a video that explains how to calculate the amount of thread needed for quilting, but this did not include the amount of bobbin thread. Is the amount the same? More? Less? Does the weight matter?

weight does matter--for instance if you use a BottomLine (Superior #80 wt?) on the bottom you will be winding much more on the bobbin than a #30 Cotton thread. So while you will actually use the same amount of thread on top and bottom (the stitch is made between the layers which is why when folks don't use a bat they sometimes have more "pokies" showing--no middle to hide that stitch)the # of bobbins you'd wind would be less with a higher weight #!

yep...weight matters. When I first started with my long arm, I used OMNI thread in the top and bobbin. OMNI was a 40 weight thread. I had an L bobbin, sometimes I did not even get one pass across my quilt before I had to put in a new bobbin (my long arm has a 26 inch neck). So now I usually use SoFine in the both, but sometimes I still need to change bobbins during one pass....It depends on how closely I am quilting. I don't even know how I would even start to calculate how much thread I would need as I free motion everything. Oh, I usually by the cones of thread for quilting and get another cone when I have about 1/4 of it left unless it is a color I use all the time, then I try and keep a full cone on hand at all times.

I read the question as whether the same number of yards are used, not how many bobbins. Certainly you can't put as much 30 weight thread on a bobbin as you can 100 weight. It seems logical that your quilt would use about as much thread on the bottom as on the top.

yep...if you are right about the question...then the actual length of the top and bobbin threads should be the same unless your tension is off or you are doing embroidery, then you would be using more top thread then bobbin thread as most embroidery machines adjust the top tension on the machine to pull more of the top thread to the bottom so as not to have the bobbin thread pokies showing on the embroidery. I suppose you would maybe want to do the same when thread painting....?????

Thanks, everyone! This helps tremendously!

Pre wound bobbins have the amount of yardage listed on each bobbin.

Great question, thanks for asking as I just learned a lot by reading the responses.