Wednesday, September 9, 2015

How to Calculate Fabric Width Differences

Jen, over at Historical Sewing, has a great article on how much yardage you would need for various garments in certain eras. I've always used the basic "5 yard skirt" method in my historical skirt calculations, but I've recently had an epiphany about amounts, and also discovering the wonderfulness of fabric that is 60''. I always never know how much to buy, and way overshoot and overspend. My very first dress I bought 11 yards!
A plaid in 60'' width fabric; I only needed 6 yards for an entire 1860's dress!

I love shopping fabric online. It's awesome. But comparing prices is sometimes tricky, because I forget to calculate the difference between 60'' fabric and 45'' fabric. If there are two different wools, and one is $8 a yard and the other is $10 a yard, I might choose the cheaper one being the cheapskate that I am. BUT...upon further research, you find out that the $10 a yard is actually 60'' wide and may even SAVE you money....if you know how to make the proper calculations as to how much you need. You won't be doing any saving at all if you buy the same amount as you would for 45'' fabric, even if you have gobs leftover.
1 yard pieces of 40'' silk taffeta

It is true that 5 yards is close to the amount you would need, but only for a 45'' fabric if you want 4 panels. Before even beginning to start fabric shopping on a budget, grab your measuring tape and pad of paper, and we'll calculate how much yardage you will need.

Start by figuring out how long your skirt needs to be. Take the longest measurement, and add enough for hem and turnover at the top, if you use that method. My finished skirt length at the longest measurement (in the back) is 43'', so I'll add 2'' for turnover at the top, and 1/2'' to attach the hem guard. Rounding up, my total cut panel length is 46''. That isn't going to change from width to width, so hang on to it!

Beginning with 45'' fabric, I'll need 4 panels. Here is the formula:

Cut Panel Length x Amount of Panels, Divided by 36'' = Skirt Yardage

This applies to 45'' and 60'' widths. So for me, I will need 5.111 yards for 45''. I'd probably round up to 5 1/4 yards. For 60'' fabric, I would only need 3.83 yards, round up to 4. That's considerably less! If I paid $8 a yard for the 45'' widths, I would be paying $42. For 60'' widths, I would be paying $40. I know, $2 isn't a huge difference, but it definitely makes some of the 60'' prices look much more affordable than you might think.

After that, calculating bodice design is pretty dicey. I've found that, a basic bodice with plain coat sleeves, you can probably get away with 2 yards even in 45'' fabric. You may even need to do a little bit of piecing, but I've had no trouble with 7 1/2 yards of that same style. For larger sleeves, you will definitely need more; 3 yards total should cover most styles. Huge pagoda or bishop style sleeves you may want to up it to 3 1/2.

For 60'' width fabric, I haven't really experimented with what the difference in yardage is, BUT...using a different way of comparing, we can figure out how much we will need. 45'' to 60'' is 3/4, or 75%. See what I did there? You will need 1/4 less fabric than in 45'' fabric. That makes a basic bodice (the 2.5 yard kind) being a little under 2 yards, with the most being 2 3/4 yards.

There you have it! I'm getting better at calculating in my head, and having the finished skirt measurement written down in my notebook makes a huge difference.

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