How Pants Work

This is how the pant crotch should fit - smoothly along the curve of the body.

This is how the pant crotch should fit – smoothly along the curve of the body.

If your pant is entirely up in your business in front (camel toe) or back (butt creep), it's because the crotch curve is not matching the body curve.

If your pant is entirely up in your business in front  or back , it’s because the crotch curve is not matching the body curve.

The crotch curve you have (red) is too shallow, or starts above the midpoint. Make the curves deeper (black curves).

The crotch curve you have (red) is too shallow, or starts above the midpoint. Make the curves deeper (black curves).

If the crotch is extra roomy, or the butt is extra saggy, you've got the opposite problem.

If the crotch is extra roomy, or the butt is extra saggy, you’ve got the opposite problem.

Your crotch curve is very close to the guides in your draft (red curve), and it needs to be a bit shallower (black curve).

Your crotch curve is very close to the guides in your draft (red curve), and it needs to be a bit shallower (black curve).

This is how the waist should fit: level with the ground.

This is how the waist should fit: level with the ground.

If the back pulls down, but the crotch fit is correct, you need to adjust the Center Back of the pattern.

If the back pulls down, but the crotch fit is correct, you need to adjust the Center Back of the pattern.

You need to add more length to the Back crotch line. You can do this by raising the crotch line above the waist, then fading the change out.

You need to add more length to the Back crotch line. You can do this by raising the crotch line above the waist, then fading the change out.

The same thing can happen in the front.

The same thing can happen in the front.

In this case, raising the front is appropriate.

In this case, raising the front is appropriate.

So you might be wondering right now, what gives, Melissa?  I mean, didn’t we start with the skirt block because we know it fits?!?

And that’s a really good accusation I’ve just imagined you making.  Here’s the sitch:

Skirt blocks are designed to skim over the body's curves. The red arrows show common places for the body to have more curve than the skirt block.

Skirt blocks are designed to skim over the body’s curves. The red arrows show common places for the body to have more curve than the skirt block.

A skirt block doesn’t follow every single curve of your nether bits.  (If you’re under 25, reading this, and wondering what I’m talking about because your clothes are all shrink-wrapped to your body, I’m sorry – we’re talking about different fabrics.  I’m talking about honest, woven, non-spandex-y goods.  They might come back into fashion again some day.)

A non-stretch skirt block actually can’t follow every curve of a curvy body, because it’s not nailed down to anything after the waist.  So if you give it the length to follow a curve at the small of the back (like, if you’ve got a well-defined bubble butt), it will look a mess – use a heavy fabric, and the curve will stand out rather than following the body.  It’s all bad.

As soon as you nail things down below the waist (with your crotch), it gets harder to skim over these curves.  As the amount of junk in your trunk increases, the differential between a skirt block and a pant block increases.  There’s fanciness you can do with slash and spread patterning to get the increase in exactly the right place, but this will get you started.

Once you’ve got your block fitted, transfer the changes back to the original draft.  I’d recommend putting the resulting block on something that will withstand some wear and tear, unless you’re only going to use it once.

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…

    1 year ago | Reply

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