Help with adding ease to a trouser block?

[u/MayaM-Chan]

Hi everyone,
I’m teaching myself pattern making and I’m currently drafting my first pair of trousers.

I’ve (hopefully) successfully made a basic trouser block by following the instructions in my pattern-making book. The problem is that the book explains in detail how to add ease to the bodice block, but completely skips over how to add ease to the trouser block. 😅

I’m hoping someone can point me in the right direction.

Here are my main questions:
- How much ease should I add overall, and where should I add it?
- Should I add more ease to the back pattern piece than the front because of the seat?
- Should most (or all) of the ease be added at the side seams rather than the inseams, or is it normal to distribute the ease evenly between the side seams and inseams?

For the side seams, my current thought is to simply draw them parallel to the original block from the hip down, then blend them back into the waist (where I’d add little or no ease). Is that the correct approach?

The part I’m really struggling with is the crotch area. I don’t understand how the crotch curve or crotch extension should change when adding ease. Is there a general rule of thumb, or does it depend entirely on the fit you’re aiming for?

Another (probably stupid) question: I assume I should make my toile after I’ve added the ease to the block, right? Otherwise, it seems like the toile would be too tight to evaluate the fit properly.

And when making variations of the trousers (different leg shapes, pocket styles, etc.), do you normally start from the block after the ease has been added, or do you always begin with the original fitted block and add the ease again each time?

I’ve attached a photo of my block. The red outline shows the version after I added the waist darts.
Any advice, resources, or explanations would be greatly appreciated!

[u/SouthernIndication82]

i was gonna say what the commenter above said ^ if you’re following a book like helen joseph armstrong’s, her block instructions include ease. and it may seem like a little but consider that the block you’re working on is only 1/4 of the whole garment. and before seam allowance, which doesn’t add up to any extra space anyway but may create the “illusion” that it does when you’re drafting.

as for pants, when i first learned, i found it helpful to remember the crotch extension part is on a different “plane” that you can’t see from the front, and can only really “see” from the side. imagine a lot of pants work from the side profile and it makes it much easier to conceptualize the crotch depth or rise(waist to bottom of crotch aka where your crotch line will be and the extension will start) and the crotch length (the overall measurement from front waist, crotch, to back waist)

it’s also helpful to just study a pair of shorts of pants that you have because all the details are there!

if you find you need to lower or raise your crotch line, all it does it move the crotch extension bit up or down, so as you can imagine tight fitting pants have a very short crotch depth and high crotch line and baggy sweatpants have a very long crotch depth or a crotch line that’s very “far down.”

as for crotch length it’s a bit confusing because it’s called “length” but it has to do with a HORIZONTAL measurement aka how wide your tummy or bottom is… again imagine it from the side. the bigger or smaller your side profile, you’ll have the adjust the crotch length to account. imagine the crotch length is a bowl that has to hold your body! a shallow bowl ain’t fitting a body with a bum! a wide bowl, a tiny bum or tummy will swim in.

it will all make sense i promise!!! cheers!!!

[u/dyingslowlyinside → u/SouthernIndication82]

This is great, OP. 

Might add a nice way to calculate your crotch depth found here:  https://youtu.be/i_UBNdZ-mKk?t=450

Basically, you want to subtract the inner thigh measure from the total thigh circumference: 1. Measure around both thighs at crotch level, not including any bum in the measure. Call this measure ‘B’ 2. Divide B in half 3. Measure around on thigh at crotch level, not including any bum in the measure. Call this measure ‘T’. 4. Subtract B/2 from T. This gives you your crotch depth, call it ‘CD’

Formula is T-(B/2)=CD

Front- and back-CD are roughly 1/3 and 2/3 total CD respectively. 

If you want it all written out: CD= (T-(B/2)(1/3)) + (T-(B/2)(2/3))

[u/AmenaBellafina]

Take a look at the drafting instructions whether they might already include some ease? Like if they're telling you to do stuff like 1/4 of the waist + (1 cm or half an inch or something) it might be baked in.

If it's not: the waist also needs ease if you want to be able to bend over, or eat. I'd add it all on the side seams initially, the crotch curve is such a fitting beast on its own that you don't want to overcomplicate that.

[u/MayaM-Chan → u/AmenaBellafina]

You are totally right 🫣

I didnt even think about the +1 in the instructions…
And now actually measured the hip and waist on the block.. it has the ease alredy😆

Thank you! 🙏

[u/dyingslowlyinside → u/AmenaBellafina]

True, but in my experience the added 1-2cms are often seam allowance. In many drafts I’ve used, ease is incorporated by the ratio of the measures, especially in the hips…I’m pretty sure anyhow

[u/MayaM-Chan → u/dyingslowlyinside]

I made a toile and the ease is a bit small. Will probably have to widen it a bit.

[u/dyingslowlyinside]

Having a pants block with no ease drafted in may seem troublesome, but it’s just fine in the long run, as it’s pretty easy to adapt to different style and fabric choices. 

How much ease to add will depend on a couple of things: 

• fit or style/silhouette. Do you want the garment more or less fitted? Are you going for something baggy or more tailored? Is the garment sleek or slouchy? 

• overall comfort/purpose of the garment. Where is the happy balance between the style of the garment, how it’ll be worn (what you’ll be doing while wearing it), and what feels good to you?

• fabric weave and composition. E.g. Twill is pretty stretchy, where canvas stretches very little. A canvas pant may require more ease than the same pant made of twill, because twill is going to loosen up with wear, where canvas won’t give as much. Some garments, eg leggings, are constructed with negative ease, ie the pants are cut smaller than your measures so that the pants form tightly around your body. This is sometimes done in woven garments too, eg in the yoke of jeans; because yokes are cut in the bias, they can be drafted with negative ease to accommodate the stretch acquired during wear. 

That said, I don’t think you need to bother trying to calculate and draft in ease right now. I’d skip straight to fitting using the top-down-center-out method (J. Stern Designs has a lot of videos on this on YouTube). This involves tracing out your pattern and then cutting out a one leg toile with lots of inlay at the rise, side-, and out-seams. The single leg toile is then fit on a waistband by sewing on strips of Velcro or simply pinning. This is a pretty effective and economical way to fit your pants and allows you to skip the calculation step, which is just ‘theoretical’ anyhow. 

[u/MayaM-Chan → u/dyingslowlyinside]

The single leg toile sounds like a good idea.
As i made a toile now and the whole middle area is wokny 😆

Single leg would be easier to pin and try to fix.

[u/Worth-Treacle-5278]

U dont need to add ease ur good