Thelma Trousers Fit Adjustments

The joy of making clothes for yourself is being able to adjust them to make them fit just the way you like. Depending on your shape, you may need to take away or add in fabric. When we size up or size down a pattern (also known as grading) we do it equally throughout, but as we know no one person is the same, sometimes these standard measurements need adjustment. So here is your very own guide to making these changes.

You will need:

Magic tape or masking tape (This will help to temporarily secure your pieces but won’t be permanent)

Pattern paper

Mechanical Pencil

Thelma Trousers Pattern.

When you are making the Thelma trousers we encourage you to start with your hip measurement. Find out what your size is on the Body Measurement Chart and use this measurement as your base size.

If your waist measurement does not fall into the same size as your hip measurement on the Body Measurement Chart you may want to grade between sizes or adjust the pattern to your specific waist measurement.

Measure your hipline and compare to the Body Measurement Chart.

If your waist falls into a bigger size than your hips…

Based on your base size (hip measurement size) we then need to calculate the amount you need to add into the waist

We do this by taking the base size waist measurement – your waistline measurement + 5cm ease (you’ll need at least a little ease for when you sit down or cycle around!)

Divide this measurement by 4, as you’ll be adding this across the whole garment both right and left of the front and back pieces.

For this adjustment you’ll need:



Let us give you an example on how we would work out how much to add to each piece.

Hip measurement 134cm/Size 24.

Base size waist on body measurement chart: 109 cm

Desired waist: 116 cm

Ease (This is 5cm across all sizes): 5cm

Desired Waist (116cm) – Waist on body measurement chart (109cm) + Ease (5cm) = (12cm) divided by 4 quarters of the body = (3cm)

Amount to add to each quarter: 3cm

Based on the example measurements above, we know we need to add 3 cm to each pattern piece. The easiest way of doing this is to slash and spread from the top of the waist down.

Starting on the front leg (A):

Temporarily tape front pocket facing (C) onto the front leg (A) to create a full trouser front matching at the notches.

Measure the top of front leg (A) and divide that measurement in two marking the centre point. Do the same on the hem of front leg (A). Create a single straight line down the middle of the front leg (A).

Once your line is drawn, remove the front pocket facing (C).

On the front leg (A) working from the top down cut through this central line, stopping a few millimetres away from the hem.

For accuracy, take a piece of dot and cross pattern paper and draw a line through the middle.

Open up the top of the front leg (A) by 3cm (1.5 cm on either side of the centre line on the dot and cross pattern paper). Your hem won’t be increased.

Tape down your dot and cross pattern paper in this position.

Moving on to the back leg:

Because the back yoke (G) and the back leg (B) sew together we will have to slash and spread both pieces.

Begin with the back yoke (G)

Create a straight line down the middle of the back yoke (G) by measuring the top edge and the centre of the notch. Draw a straight line through these two points.

On the back leg (B) mark the half way point of the notch, and mark the centre of the hem. Create a straight line between these points. Mark in the seam allowance on the bottom of the back yoke (G) and top of the back leg (B).

Temporarily overlap the seam line of the back leg (B) and back yoke (G). Masking tape these pieces together. We temporarily attached the back yoke (G) to the back leg (B) so we can ensure we open the back yoke (G) and back leg (B) an even amount.

As above, draw a centre line down your piece of dot and cross pattern paper.

Open the top of the back yoke (G) by 3cm

Before separating the yoke from the trouser, mark in the measurement between these pieces. For this example the distance is 2.8cm.

Now these measurements are recorded, separate the back yoke (G) from the back leg (B).

The top edge of the back yoke (G) will be open by 3cm

The seam line will be opened by 2.9cm.

The hem will not be changed.

Now we will explain how to adjust the waistband.

Because we’ve added 12cm across the top of the trouser legs we need to do the same thing on our waistbands.

Notched on your long waistband (H) is your centre front, and notched on both waistbands (H&I) are your side seams.

On your waistband pieces (H&I) find the half way point between your centre back and side seam. Mark this with a vertical straight line through the whole waistband.

On your waistband pieces (H&I) find the half way point between your centre front and side seam. Mark this with a vertical straight line through the whole waistband.

On your waistband pieces (H&I) cut along these two vertical lines and open each section up by 3cm.

Now, you can follow the instruction book as normal to complete your Thelma Trousers.

If your waist falls into a smaller size than your hips…

Based on your base size (hip measurement size) we then need to calculate the amount you need to decrease from the waist

We do this by taking the base size waist measurement – your waistline measurement - 5cm ease (we’ve already added ease to the pattern.)

Divide this measurement by 8, as you’ll be decreasing this across the whole garment both right and left of the front and back pieces. 

For this adjustment you’ll need: 

Let us give you an example of the measurements you see on the Body Measurement Chart.

Hip measurement: 105cm/Size 14.

Base size waist on body measurement chart: 85 cm (Size 14) includes 5cm ease

Desired waistband: 80 cm (Size 12) includes 5cm ease.

Waist on body measurement chart (85cm) - Desired Waist (80cm) = (5cm) divided by 8 seams on the trousers = (0.6cm)  

Amount to reduce on each seam: 0.6cm 

Based on the example measurements above, we want our size 14 trousers to be reduced so they fit our size 12 waistband, we know we need to take away 0.6 cm from each side of each pattern piece. The easiest way of doing this is to decrease the pattern by 0.6 from the top of the waist down to the hip. We wont reduce our pattern past the hip as the hip size was correct.

Starting on the front leg (A): 

Temporarily tape front pocket facing (C) onto the front leg (A) to create a full trouser front matching at the notches. 

Measure and mark 0.6cm in from the centre front of the front leg (A). Using a pattern master or ruler draw a straight line from the lengthen and shorten line, to the marked point on the centre front of the front leg (A). 

Measure and mark 0.6cm in from the side seam of the front leg (A). On the side seam draw a slightly curved line from the lengthen and shorten line, to marked point on the top of the trouser leg (A) 

Cut through this drawn in line reducing the top of the trousers by 0.6cm on both the centre front and side seam.  

Moving on to the back leg:

Because the back yoke (G) and the back leg (B) sew together temporarily tape together these two pieces so the centre front and side seams meet. Don’t worry if the back yoke (G) overlaps the back leg (B) in the centre. 

Measure and mark 0.6cm in from the centre back of the back yoke (G).

Measure and mark 0.6cm in from the side seam of the back yoke (G). 

Using a pattern master or ruler draw a straight line from the lengthen and shorten line, to the marked point on the centre back of the back leg (B) up through the back yoke (G).  On the side seam draw a slightly curved line from the lengthen and shorten line, of the back leg (B) to the marked point on the back yoke (G). 

Cut through this drawn in line reducing the top of the trousers by 0.6cm on both the centre back and side seam.  Once cut the back yoke (G) can be separated from the back leg (B) 

For your waistband pieces (H & I), all you need to do it cut out the smaller size. In this case, you’d cut the size 12.

Now, you can follow the instruction book as normal to complete your Thelma Trousers.

Lydia HigginsonComment