How Pants Work

You’re going to want to put your skirt blocks on a larger sheet of paper.  It should be roughly half again as wide as the Full Hip measure of the block, and at least as long as the Waist to Ankle measurement you just took. I like to give myself a little breathing room, as it were, when it comes to paper.  (But only just a little.  Like, 6″, not 4′.  I have seen so many students garb a 4′ long hunk of paper and trace a bodice block in the middle.  I don’t get that, and it makes me feel tremendously curmudgeonly.)

Using the square again, locate the crotch depth on the Center Front. The Back crotch should be placed lined up with the front crotch.

Using the square again, locate the crotch depth on the Center Front. The Back crotch should be placed lined up with the front crotch.

Ah!  Wait!  Missa, you didn’t label front and back!

Don’t worry.  The back skirt is on the right, and has the longer darts.  Because the human body, that’s why.

At this point, you will likely have a situation where measuring from the back crotch to the waist will not give you the same thing you got in front.  Try not to worry to hard about that.  It’s pretty normal.

This is the human body (again).  If you take a look at the shape of this skirt block, the Center Back actually dips lower than the Center Front, and both of them dip from the side seam.  That’s telling us that this block was made for someone with a defined hip curve, some degree of abdominal arc (aka, a panza, marshmallow fluff, or whatever you prefer to call your tummy fats), and a very flat bum.  I mean, Oklahoma levels of flatness are going on in that there derrière.

At some point, this was absolutely the fashionable shape, because this is a reduced and vectorized version of a block I scanned from the text I used as a student.  My own personal blocks tend to go up at Center Back.  It’s pretty rare for CF and CB to be level in skirt block, which is totally not a problem for a skirt block.

For a pant block, it’s going to lead to tragedy, because if you measure the crotch depth down from the waist at both Center Front and Center Back, the crotches won’t be level, so the front and back inside leg seams will be different lengths.  It’s just quite the situation, isn’t it?  I vote for avoiding that.

Extend the skirt sloper at CF and CB so that it can go around the thigh. For a reasonably close fit, start with 20% of the block with (at hip) at Center Front and 25% at Center Back.

Extend the skirt sloper at CF and CB so that it can go around the thigh. For a reasonably close fit, start with 20% of the block with (at hip) at Center Front and 25% at Center Back.

I’m biased, and so is this draft – there’s just more of me in back below the waist than in the front.  Thighs of an Olympian speed skater, I do not have.  (Thighs of a 40 year old teacher who has spent way too much time in front of the computer lately?  Those, I got.)

Find the midpoint of the Crotch Depth, Front and Back.

Find the midpoint of the Crotch Depth, Front and Back.

Draw a smooth curve from the midpoint of the Crotch Depth, out to the end of the Crotch Extension for both the Front and the Back.

Draw a smooth curve from the midpoint of the Crotch Depth, out to the end of the Crotch Extension for both the Front and the Back.

Maaaaaaajor Watchpoint: Remember how you measured you Crotch Length earlier?

If you measure the two curves you just drew, and they are less than that Crotch Length, you're going to have some problems getting those pants on.  Since we know that won't work, let's fix it now.

If you measure the two curves you just drew, and they are less than that Crotch Length, you’re going to have some problems getting those pants on.  Since we know that won’t work, let’s fix it now.

Enlarge the crotch extensions until the curve is the correct length.  For most body types, the back will be a larger extension than the front.  Check and repeat, if needed.

Enlarge the crotch extensions until the curve is the correct length.  For most body types, the back will be a larger extension than the front.  Check and repeat, if needed.

This is one of the times when flexible rulers are supremely awesome, btw.

Now we basically have a short, but we’re going for a pant, so we’re going to have to lengthen this.

Subtract your Crotch Depth measurement from both your Waist to Knee and Waist to Ankle measurements.  We’ll call these new numbers the Adjusted Waist to Knee and Adjusted Waist to Ankle.

Measure down from the Crotch Depth the Adjusted Waist to Knee and Adjusted Waist to Ankle measurements. Square across from Front to Back.

Measure down from the Crotch Depth the Adjusted Waist to Knee and Adjusted Waist to Ankle measurements. Square across from Front to Back.

Find the middle of the Ankle line, both Front and Back. Square a line up to the top of the pant. This is the crease line.

Find the middle of the Ankle line, both Front and Back. Square a line up to the top of the pant. This is the crease line.

Crease lines won’t necessarily line up neatly between darts, or be in line with the bottom of a dart.  It’s nicer when they do, so you may decide to move your darts.  Or, you can do the sneaky thing most slacks do and stop pressing the pant at the hip.  ;)

Some drafting books go through shenanigans to offset the inseam and outseam of the pant so that they don’t line up.  I think this is so that there’s no lump in the middle of the pant hanger, if you’re using one.  About half of my work pants are like this, while the other half have seams that line up.  I prefer it when the seams line up, because it makes it easier for me to iron the pants.  (Riiiiight – because I spend so much time ironing my pants.)

So, now you’ve got a pant block.  Let’s talk about the sewing up, just in case….
Next: Sewing Directions

2 thoughts on “How Pants Work

  1. Anna-Carin Betzén says:

    Great instructions! Good point on how to measure the crotch depth, that will help when fitting commercial patterns too.

    BTW, there may be a problem with the scaling of some of the pics – on my computer, the silhouette pics are displayed 2335 px tall…

    11 months ago | Reply

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