A quick look at the top 5 most common pant alterations and an explanation on how you can alter the pattern!
Pattern blocks, a disclaimer!
Pattern blocks are often made from a set of standard measurements, and sometimes made from our own measurements. In theory, it seems like they should be a perfect fit, every time. Unfortunately, this is not always the case.
A few ill-fitting areas is normal and can result from subtle nuances in our individual bodies. For example, some of us are slightly pigeon toed, or have knee knock, or we have bowlegs. Maybe the angle your leg comes out of your hip is slightly different. Whatever the nuance, we all have them and sometimes we may have a few! And that is what makes us all so unique!
However, this is also the reason why store bought clothing doesn’t always fit us the way we’d like. No worries! Once armed with the knowledge of how to make these simple pattern adjustments, we’ll be on our way to making awesome fitting pants! (or shorts)
Note: Keep in mind, these techniques can be applied to pattern blocks, PDF sewing patterns, or any home sewing pattern.
Why fit muslins are so important…
Although it may seem like our pattern blocks should fit perfectly right off the bat, this is not always the case. This is why it is so important to always sew a fit muslin. After a fitting, we can determine what changes need to be made.
These top 5 common pattern adjustments can be applied to a pattern block to create a new, better fitting block! This will help to ensure any future styles will fit just as well! Also, we can apply these changes to any PDF or home sewing pattern.
Of course, there are heaps more than 5 alterations. However, once you understand a few of them. . . You’ll have the knowledge and understanding on how to make more advanced pattern adjustments!
Slash and Spread | Slash and Close
If you’re not familiar with the slash and spread or the slash and close technique, now’s the time to familiarize yourself! In the most basic sense, slash and spread is used to create fullness and slash and close reduces fullness.
There are a ton of great resources out there that can be found by a simple Google search. Here’s a quick illustration of the basic principle of the slash and spread.
Note: Slash and close would the exact opposite!
Full Thigh
What is a full thigh adjustment?
A full thigh adjustment is used when a pant is a bit too tight around the upper to mid-thigh. This adjustment will not alter the length of the rise, waist, or inseam length. It is meant to simple add a little extra space in the thigh.
How to adjust the pattern…
First, determine the approximate measurement that the pant will need to be increased. Divide this measurement by 2 and this new measurement will be applied to the front and back equally. Make note of this number.
Now, draw a line from the crotch point, angling it slightly downward at approximately a 45° angle. Then following the grainline, continue the line down to the bottom of the pant.
Starting at the hem, cut along the line to, but not through the crotch point. You need to leave a little bit of the pattern connected at the crotch point to act as a hinge. Next, swing open the pattern to the measurement determined earlier.
You can use small rectangular paper scraps and tape to secure the pattern. Finally, retrace the pattern onto new pattern paper. Blend and true all of the curves and lines.
Note: If this adjustment is used in reverse to create a more narrow thigh, it could result in the ankle being to narrow.
Shorten Rise
Why shorten the rise?
Shortening the rise pattern adjustment is used when the rise of the pant is too long. This might result in the pant fitting higher on the waist than desired. This adjustment will not affect the side seam or waist measurements.
How to adjust the pattern…
First, determine the approximate amount the crotch needs to be shortened. Divide the measurement by 2 and record this measurement. It will be applied to the front and the back equally.
Starting around the middle of the rise, draw a horizontal line to the side seam. Starting at the rise, slash across the pattern leaving a little bit of the pattern connected to be used as a hinge. Next, overlap the pattern according to the measurement recorded earlier. Secure pattern closed with tape.
Finally, retrace pattern onto new pattern paper. Blend and true all line and curves.
Shorten crotch depth
Why shorten the crotch depth?
Shortening the crotch depth is used when there is excess fabric, or bagging in the crotch. This adjustment will not alter the inseam length or the waist measurement.
How to adjust the pattern…
First, determine the amount of excess fabric in the crotch. Divide this measurement by two and record the number. It will be applied to the front and back equally.
Starting around the mid-rise, draw a horizontal line across the pattern. Cut all the way across the pattern and separate the top from the bottom. Next, overlap the two pieces according the measurement determined earlier.
Secure pattern by taping it back together. Trace pattern onto new pattern paper. Blend and true all lines and curves.
Lengthen back rise
Why lengthen the back rise?
Lengthening the back rise is used when the center back seam is a little snug in or under the bum. Basically, it is used when the pant gives you a wedgie! This adjustment will not alter the inseam or side seam length.
How to adjust the pattern…
First, determine the amount the back rise should be lengthened. Record this measurement. Next, draw approximately three horizontal lines across the pattern. It’s best to draw one around the mid-rise, and one above and below.
Starting at the rise, cut across the pattern to but, not through the side seam. You will need to leave a little bit of the pattern attached at the side seam to use a hinge.
Spread open the pattern to the measurement recorded earlier. It is best to distribute this measurement equally between all three spreads.
You can use small rectangular paper scraps and tape to hold the pattern in place. Finally, retrace the pattern onto new pattern paper. Blend and true all curves and lines.
Adjust waist
Why adjust the waist measurement?
This pattern adjustment is used when the waist measurement needs to be increased. This adjustment will not alter the inseam or side seam lengths.
How to adjust the pattern…
First thing first, determine the amount the pattern needs to be increased. Divide measurement in half and record that number. The amount will be applied equally to the front and back pant.
Now, there are a few ways to make this adjustment. The first way to make this adjustment is to starting at the mid-hip area, draw a line to the waist at approximately a 45° angle.
Starting at the waist, cut to but not through the pattern. You will need to leave a bit of the pattern attached at the side seam for pivoting.
Next, open the pattern to the amount determined earlier. Secure pattern in place by taping small rectangular pieces of paper in the opening.
The second way is to slash and spread from the top of the waist down (maybe use a dart if available).
For both alterations, retrace pattern onto new pattern paper. Blend and true all lines and curves.
Note: this adjustment could be done in reverse to decrease the size of the waist.
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I have some questions about the shorten crotch adjustment:
1. Would this be equal to altering for petite sizes?
2. How would this work with chino style pants with pockets? I don’t want to make the pocket opening smaller.
3. How do I determine where this adjustment would be if the hip line is not marked on my pattern?
I have 3 questions on shortening the crotch depth:
1. How do I handle the pockets on chino style pants if you shorten the crotch depth? I don’t want to make the pocket opening smaller.
2. Is this the equivalent to altering pants pattern for petite?
3. How do I determine where this altering line should be if my pattern doesn’t have a marking for this?
Hi Ruth, thank you so much for your valuable and useful explanations of how to altering pants. I am having weird body shapes after several surgeries, specially around the belly. My front arc of the waist is 7cm larger than the back arc. It was very difficult to find fitting pants for me. (my front waist is size 18 and back wast is size 16/14. Isn’t it funny?)Finally I decided to make a pattern for myself but the success rate was about 75%. With the help of these instructions, I managed to fill up the other 25% of my mistakes. Thanks a lot again ans wish you all the best!
Thank you very much. I am a newbie sewer. I have managed to make a pair of long shorts. From a online pants block (don’t know if I can link it here or not) Its turned out really well for my first go. I have done it in Calico. They are big all over the place. I wonder where would I even start to get them to be a bit more snug. Waist is a bit big, but I should be able to take that in, The legs are wider than I want.
Didn’ t see any instructions on how to increase crotch length with the slash method for a thick body crotch
Hi Ruth: I have a lot of knit pants – some casual and some dressy. The problem I have with every pair of pants I own is that when I put on my pants the elastic waistbands come up way over my waistline where I feel comfortable wearing my pants – sometimes the elastic waistband comes up right under my bra. I end up having to “roll” the excess pants fabric so that my pants fit nicer. I have been trying to research the internet to learn how to correct this problem. How do I get rid of all the excess fabric in my pants that comes up way over my natural waistline?
Hi Eileen, do you have a short torso? It’s hard for me to say because I don’t know your body shape. But, in theory, you should be able to just shorten the side seam and rise. If you can easily pull the elastic out of the pants, just cut off the amount on the top that you need. Then just fold over your elastic casing and add it back in!
Thanks so much for this. I’ve sewn for many years. Have recently gotten back to making my own clithes and have started to make my own patterns for the first time. I could not figure out how to add to the back crotch depth without adding to the inseam or the side seam. This was very helpful.
So glad to hear that Tracy!
I’m very short but also curvy. Consequently, my pants have never fit correctly, with the front waist almost always coming to rest right under my bust! This is an informative tutorial that will help me get my pants patterns in shape. Thanks!
Thanks, Shari! Good luck w/ your adjustments!
Excellent. loved it. I would like to ask another question. What correction should be done to the pattern, when I sit and the back belt is pulled down. meaning, that it does not stay at the level of the waist.
waiting for your replay.
Thanks,
Ronit
I found this one of the best tutorials I’ve ever read. Thank you.
You’re so welcome Gwen!
Very helpful! Thank you.
You’re welcome!
Hi,
I have unstitched jeans fabric that i would like to stitch to resemble Levis Wedgie fit jeans but front crotch also decreases while reducing back rise.
What to do to keep things plain at front, have high rise fitting and still get snug fit that separates buttocks ?
Hi! I love the look of the wedgie fit! I’m not sure that I can help you with that question. This post relates to altering pattern blocks, not existing garments. I don’t know that an alteration like that would be possible. I guess it would depend on the fit of the jean you unstitched.
For Adjust waist, why don’t u just tract a new line on the paper, why do you want to slash or cut the paper ? isn’t it more work?
2. and for the first one (45 angle from mid hip line), it only increase from the side seam, not evenly increase from the center and side, is that a correct way to do? I thought it should evenly increase from sideseam and center.
thank u 🙂
Hi Sabrina,
As in a lot of trades, there is more than one way to achieve same goal. There are many ways you can alter pants to make them fit. The thing with pattern making for the home sewer is that it can be individually specific to your body type and what fits you the best! This is just an overview of some of the ways alterations can be made. There are so many more!!!