How to Fit a Corset Mock up?

First off, unless something went horribly wrong, it is impossible to look at the pattern and tell if it will fit well. Patterns don’t contain that information but a well-made mock up will reveal it all! And with that said, let’s learn how to fit a basic corset mock up!

No matter what kind of pattern we use, standard size or made to measure draft, we need to test it with a mock up (or two) to tweak the little details that make everybody unique.
If the body is unique, fitting a corset for it must be unique as well. No way around it, really and that’s a-okay!

Creating a universal set of corset fitting rules that will always work, on everybody, is simply impossible but we can go through some of the usual issues and ideas on how to address them to get a good start.

Since I encourage every corset maker, old and new, to pre-fit standard sized corset patterns through methods such as Grading between sizes and Changing circumference distances, most major pattern changes will be applied before the mock up is created.
This way, we end up just fine tuning the patterns fit.

Remember, fitting process starts before the corset mock up is laced on!


  1. Gather all the fitting tools before lacing into the mock up. (Fig. 1)
    You will need a measuring tape, colored pens, pins, tarp scraps, small scissors.
  2. A big mirror is always helpful but smart phones are just better.
    Set up the phone one a shelf or a stack of books to get it to proper height.
    Take loads of pictures from all angles as well as video footage.
  3. Tie long hair in a bun or a similar style. (Fig. 2)
  4. Wear similar clothing for fitting process as you’ll wear the finished corset with.
    Don’t wear a bra under a overbust/midbust mock up if you don’t plan on wearing it under a finished corset!
Tools needed for fitting basic corset mock up

Figure 1 : Basic corset mock up fitting tools

  1. Lace on the mock up slowly while constantly checking how mock up sits on the body.
    Readjust the mock up, clothing and/or soft tissue as needed.
    Help your “girls” out for best results. ; )
  2. Have the mock up waist line sit on the body waist line.
    Rest of the circumferences don’t have to match up perfectly.
    They will be dealt with during fitting.
  3. Be mindful of the back lacing gap when lacing in!
    Lace the mock up with the back lacing gap that the pattern is drafted for.
    Make sure sides are parallel!
  4. Keep a neutral relaxed stance when fitting.
    No bending, extending or arm lifting!
Corset mock up worn and ready for fitting

Figure 2 : Ready for fitting a corset
(Using free pattern LOLITA)



After assessing the mock up closely, as well as marking and taking note of all fit problems that it has, it’s time to start applying potential solutions.
Since the mock up is made in such a way that all seam lines and seam allowances are accessible, we focus all of the fitting changes on the seam lines.
For consistent results, keep as organized as possible, working on ONE problem area at a time!



If the mock up can fully (or more than it should) be closed in the back but it’s has been drafted to fit with a specific back lacing gap… the overall size is simply too large. We can still get use from this mock up.

  1. Measure the mock up back lacing gap, if there is any.
  2. Calculate the difference between the mock up back gap and intended back gap.
  3. Spread the difference between all seams (excluding center front).
  4. Sew new seam lines on the mock up. Yes, over waist tape too.
  5. Try it on and analyze the fit again before going forward.


If the mock up can’t be comfortably laced with the drafted for back lacing gap (or lack of it), the overall size of the mock up is too small.

  1. Measure the worn back lacing gap.
  2. Calculate the difference between the mock up and drafted lacing gap.
  3. Divide the difference between all seam lines (excluding center front seam).
  4. Remove the waist tape.
  5. Sew new seam lines.
  6. Rip apart old seam lines.
  7. Sew on a new length of waist tape.
  8. Try it on and analyze the fit again before going forward.

In the rare case of not having enough seam allowance width to sew new seam lines to enlarge the mock up size, a completely
new mock up should be made.
Use the difference between back lacing gap of the mock up and pattern as a guide when deciding how many sizes to go up.

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On marked areas that are too loose, we want to pinch the mock up on the seam line until it sits snug on the body. Basically, we are making a „dart“ deeper.

When we are working with a larger area, we might get best results if we spread the adjustments on more than one seam line in that problem area.

First pinch the seam line. Play with it a bit. See and feel what looks good. When you are happy with the temporary adjustment, mark the new seam line on the area you are adjusting. Pin or clip the change in place before moving to the next problem area.

Nothing is set in stone! You can always come back and readjust the initial changes made.

  1. Identify the area that is too loose/large by poking your hand under mock up edge to feel the fit. (Fig. 3)
    A snug fit without the edges pressing into soft tissues is preferred.
    Fit can be slightly on the looser side but not enough to easily shove your hand under the mock up.
Fitting a corset mock up that is too large

Figure 3 : Corset area fits too loose

  1. Pinch the seam line(s) where the mock up feels very loose.
    Do it just enough fabric to have the mock up sit snug on the body.
    If the pinched fabric created pulling in other mock up areas, pinch neighboring seams to spread out the reduction.
Pinching the seam to improve how the basic corset mock up fits

Figure 4 : Pinching the excess material on seam line

  1. Pin or clip the seam line where you want to remove fabric. (Fig. 5)
    Clips are a bit easier to use when fitting mock ups on yourself but pins work just as well.
    Have a look at the fit of this area. Is there any wrinkling/gaping that can be improved by fiddling with the same seam line.
Clips holding the corset mock up fit adjustment pinched fabric in place

Figure 5 : Using clips to hold pinched fit adjustment

  1. When happy with the shape & amount of adjustment, mark out the shape of new seam line. (Fig. 6)
    Mark the new seam line on BOTH sides!
    Fine tip marker/pen work the best for this job.
Marking the new seam line on basic corset mock up

Figure 6 : Marking a new seam line

  1. In the case of spreading the adjustment over more than one seam line, work with one seam at a time! (Fig. 7)
    Repeat the same process, same way just on a different seam line.
    Remember! Things are not set in stone! You can go back & readjust things
Pinching another seam line for a better basic corset mock up fit

Figure 7 : Adjusting neighboring seam line
(if needed)

  1. Address fit issues in problem area as best as you can before moving to a different problem area. (Fig. 8)
    It’s OK if it doesn’t look perfect!
    When an area is not cooperating, leave it & move on. You can always come back to it & give it another try later.
Using more clips to hold corset mock up fit adjustments in place

Figure 8 : Problem area fitted, adjusted & prepared


With this fit of a basic corset mock up issues, we are looking at signs of unpleasant pressure and/or flesh spilling over the corset edges. Top or bottom edge, doesn’t matter. Since the problems is the complete opposite of the too loose problem, instead of pinching a seam line on the problem area, we cut it open.
Be gentle and take it slowly!

This method is sometimes referred to as “slash and spread”. Similar method is used in manipulating flat drafted patterns.

Different fit problems require different solutions. This is very true when it comes to ADDING room as opposed to removing it.

  1. Start by making the ribcage edge & Iliac Crest on the mock up for a better idea of one’s hard skeletal limits. (Fig. 9)
    We can’t move bone and most discomfort fit issues are tied to lack of space over skeletal bones.
    Shape between ribcage & Iliac Crest is much softer & more malleable.
Marking bottom of rib cage on basic corset mock up

Figure 9 : Marked rib cage as a control point

  1. Locate the area where there is the most flesh spilling over mock up edge and carefully cut the seam line open. (Fig. 10)
    Be very careful not to cut the fabric of the mock up, clothing or flesh!
    Slow & steady wins the race!
Cutting into basic corset mock up seam line using thread snips

Figure 10 : Cutting seam line open using thread snips
(Not sponsored)

  1. You can gently rip the seam line. Be careful not to overdo it! (Fig. 11)
    Depth of the rip depends on fit issue area but start with less that you think is needed. You can always make it deeper.
    Short stitch length is keeping the mock up together so don’t skip that step!
Opening seam line for basic corset mock up adjustment

Figure 11 : Seam line opened up over the adjustment area

  1. Cut a piece of fabric a bit larger than the size of adjustment & insert it on the inside. Pin one seam line to the fabric insert. (Fig. 12)
    Make sure everything is smooth! Fabric, mock up, seam allowance… everything!
    Now you can safely play with the adjustment.
Basic corset mock up seam pinned to inserted fabric

Figure 12 : One side of seam line pinned to fabric insert

  1. Adjust the other seam line in place. Do your best to create a comfortable & flattering shape.
    Pin everything down! (Fig. 13)
    If the amount of inserted space is very wide, explore the option of opening another seam line & spreading the extra space over two (or more) seam lines.
Cut and spread method used on basic corset mock up

Figure 13 : Fit adjusted & other side of seam line pinned to fabric insert

  1. When you are satisfied with the adjustment done to a seam line, mark the new seam line on fabric insert. (Fig. 14)
    Find the middle of the added space on the widest point & connect it to the mock up seam line using a flexible ruler.
    Repeat the same on ALL other adjusted seam lines!
New seam line drawn on to basic corset mock up fabric insert

Figure 14 : Middle of added inserted fabric is the new seam line


Sometimes the fit of a basic corset mock up can visually look good but it really doesn’t feel very good. You should be over the moon because of how wonderful it looks and still, corset feels uncomfortable. Problem might be in very small details so we have to check and see how we can change those little things.

First method for ADDING room for a more comfortable smoother fit focuses on a corset that fits so tight in places, if forces soft flesh over the edges. Adjustment is fairly straight forward & simple to do because the seam gets opened from the edge towards the waist line.
This isn’t the only fit issue that gets solved by ADDING space.

Ribcage & hip bones (Iliac Crest in particular) can be especially sensitive to pressure which can lead to discomfort even if the general fit doesn’t look bad. In this case, it is better to target that specific problem area instead of ripping the seam line apart from the edge & potentially interfering with well-fitting areas of the mock up.

Inspect your mock up carefully before deciding what fitting method to apply to the problem area!

  1. In case of experiencing discomfort over the ribcage or Iliac Crest but no flesh oozing over edges, mark discomfort area over ALL affected seam lines. (Fig. 15)
    Be warned that this adjustment usually results in a more cupped hourglass silhouette!
Marking the part of basic corset mock up that needs more room

Figure 15 : Area needing adjustment marked

  1. Carefully unpick seam line on marked area. (Fig. 16)
    This should instantly make the mock up more comfortable.
    Still feeling discomfort? Mark it & deepen the cut in the seam line.
    Spread on multiple seam lines if needed!
Opened seam line on the basic corset mock up

Figure 16 : Seam line cut open with seam ripper
(Not sponsored)

  1. If seam allowance width allows it, use clips to for the new seam line shape. (Fig. 17)
    Often, just a little bit of extra room is needed to remove discomfort.
    Apply basically the same process as with the case of the mock up being too large but ADD space.
Seam allowances used to add space to the basic corset mock up

Figure 17 : Seam allowance width used for fit adjustment

  1. When seam allowance width isn’t enough to add needed room, use fabric inserts. Pin one seam line to secure it in place. (Fig. 18)
    Insert needs to be larger than the size of the needed adjustment.
    Fiddle around with the shape & fit of problem area for best results.
One seam pinned on to fabric insert with pins

Figure 18 : Using fabric insert for fit adjustment
One side pinned to fabric insert

  1. Pin other seam line to fabric insert when happy with the fit. (Fig. 19)
    As always, adjustment can be applied to multiple seam lines.
    Also, it can be revisited & changes later in the fitting process.
    Don’t stress out over the idea of perfection!
Using pins and fabric insert to add room to basic corset mock up

Figure 19 : Fit adjusted & other seam pinned down to fabric insert

  1. Finish the fitting adjustment by marking the new seam line on the dead middle of added fabric! (Fig. 20)
    If needed, repeat the same process on ALL seam lines affected by this adjustment.
New seam line drawn on to the middle of fabric insert of the basic corset mock up

Figure 20 : New seam line marked on fabric insert


With the vast majority of fit issues addressed with pinching, pinning and ripping, we can finally have a look at the general shaping of mock up edges.

The easiest change to do is to shorten the edge line. Draw the new edge shape on the mock up with a pen.

That’s basically it!

  1. Visualize the new edge shape by taking pictures of the mock up worn & doodling on them. (Fig. 21)
    Take your time. Play around with ideas.
    Having design sketches is great but pictures tell a more detailed story.
Higher edge shape visualized for a better fit of a basic corset mock up

Figure 21 : New corset bottom edge shape visualized

  1. Start by marking the highest point of the new edge shape. (Fig. 22)
    Always have pictures handy for reference.
    Don’t focus on getting it perfect.
    Just do it! Adjust as you go.
Marking highest edge shape point

Figure 22 : Marking the highest point of new shape

  1. Press the seam allowances to the side & down to be a nice flat surface. It makes it easier to draw the edge shape over it. (Fig. 23)
    Keep in mind that seam allowances on the outside of mock up does make it a bit more difficult draw on the mock up as well as it makes the corset look a bit bulkier.
Pressing seam allowances down to fit corset mock up

Figure 23 : Pressing seam allowances down

  1. When you are happy with the shape of the front part of new edge, start working on marking the back portion. (Fig. 24)
    Use a mirror/smart phone as much as possible to help out with working on back parts.
    Don’t expect lines to be tidy. That’s OK.
    Clean them up later!
Marking the start of higher edge on the back corset panels

Figure 24 : Sketching the new edge shape

  1. Draw the edge line in the back as far as possible. (Fig. 25)
    Pull the mock up edge to prevent wrinkling of fabric due to torso twisting.
    Pulling on the mock up also helps us anchor on to the mockup, to better focus on drawing the new edge line.
Pulling on the corset mock up edge while twisting while working on the fit of corset mock up

Figure 25 : Pulling the corset mock up edge while twisting

Even though it is rather challenging to do any type of fitting adjustment on the back of the mock up, our goal is to do the very best that we can while wearing the mock up.

Many things can & should be further adjusted, smoothed out, after the fitting session.

In the case that you aren’t able to do much of adjustments on the back of the mock up, consider dividing the fitting process in more stages.

Unlace the basic corset mock up. Make some eyeballed changes to the back of it. Try the mock up AGAIN.
See how it fits.


Extending or raising an edge on a mock up is a bit more complicated just because we have to ADD instead of reduce. Also, we MUST fit a corset mock up again, specifically over the new extender areas.

A few pieces of mock up fabric, some pins, ruler & a sharpie is all you need to create a longer/higher corset edge.
Everything starts with building up more space so we can simply draw new shapes and designs on it. Rest is totally up to you.

This method is not a very good choice for turning an underbust corset into an overbust. Too much work. Simply not worth it. There are other much better ways.

  1. Cut a piece of mock up fabric of the general size of your new edge shape. Tuck in into the mock up where ever the edge will get changed. (Fig. 26)
    Feel free to use more smaller piece of fabric just make sure to pin them securely together & to the mock up.
Placing fabric extension piece in place

Figure 26 : Mock up extension fabric piece placed in position

  1. To visualize your design, take pictures of the extended mock up & draw the shape of new edge on it for future reference. (Fig. 27)
    Take your time. Play around with ideas.
    Having design sketches is great but pictures tell a more detailed story.
New top edge shape design visualized on mock up

Figure 27 : New corset top edge design

  1. On the mock up, start the new edge shape by extending the center front, side seam (and center back seam if design calls for it). (Fig. 28)
    Make these lines a bit longer than you think you need them.
Marking the front and side seams

Figure 28 : Marking extended center front seam line

  1. Trace the edge of the old mock up edge on to the fabric extension piece. (Fig. 29)
    This will make it a bit easier to transfer mock up changes to the pattern if extension fabric pieces need to be unpinned from the mock up.
Transferring shape of the mock up on to fabric extension

Figure 29 : Transferring original mock up edge on to fabric insert

  1. Pull on the extension fabric to keep it smooth while drawing the new edge shape on it. (Fig. 30)
    Try to be realistic when it comes to how much to raise/lengthen the edge.
    An underbust corset should still be an underbust corset!
Pulling on to the fabric extension while drawing new edge line

Figure 30 : Pulling fabric extension for smoother drawing surface

  1. Extend mock up seam lines no to the fabric extension pieces using a ruler. (Fig. 31)
    We want the new part of the seam line be a smooth continuation of it.
Extending seam lines so they reach the new edge

Figure 30 : Extending ALL new seam lines so they reach new edge


ALL of these methods can be applied anywhere on the mock up problem areas to properly fit a corset mock up, be it close to the mock up edges or smack dab in the middle of it.

Take in or let out the seam line where ever it is needed, however much is needed! Any fit adjustment made on one side of the mock up NEEDS to be made on the other side as well.

Try to copy the adjustments as close as possible.

By doing this, mock up will reveal if all adjustments work well together. If there is a need to go back and make more modifications.

During the fitting process, you might have to work with asymmetry „issues“.

When this is the case, there are two options.

  1. Fit the two sides separately for a close fit on the natural shape.
  2. Fit the larger side (in comparison) of the mock up with the goal of padding out the shape for the other side, to achieve visual symmetry.

They are a matter of preference as well as the use of the finished corset but one thing is for sure, another mock up MUST to be made to achieve a good fit!


It will ALWAYS be difficult to fit a mock up on oneself! There is no way around it but it is a skill and any skill can be learned and practiced. You can do it!

To get a proper fit, it might be necessary to lace in and out of the mock up a couple of time to achieve a proper fit in the back of the mock up.

Expect a lot of trial and error as it is a part of the process.

With everything said and done, it is well worth it as all the hard work will result in a comfortable and beautiful corset.



Only thing left is to transfer ALL changes made on the mock up on to the corset pattern and you can create your very own AMAZING corset!