DIY Professor Trelawney Costume – Tunic Home » Costumes And Cosplay » Halloween Costumes And Accessories » The Harry Potter Movies » DIY Professor Trelawney Costume – Tunic

For this year’s (2022) Halloween my family and I decided to dress as characters from the Harry Potter movies. In this blog post, I’ll describe how to make a Sybill Trelawney outfit (a green tunic, that I’m going to wear myself ;). (Sybill is a fortune-teller and professor at the Hogwarts School of Witchcraft and Wizardry) who taught divination – insights into future events. To sew the tunic it is useful to have some experience with sewing garments and to know what is a facing, underlining or top-stitching, button loops, bfor example.

In this tutorial you will learn:

In this blog post, I will describe how to modify an existing pattern in order to make a pattern for the professor Trelawney costume tunic.

To sew a professor Trelawney tunic you will need the following:

  • Existing basic hoodie pattern with a set-in sleeve
  • Green light-weight fabric with a leaf pattern
  • Beige fringe trim
  • 20 green buttons – about 1,5 cm (5/8”) in diameter
  • Large paper or tissue paper (in case you have to modify the sleeve pattern)
  • Lightweight interfacing (useful, but optional)

Pick a hoodie or t-shirt pattern that is one-two sizes larger than you normally wear. This way you will achieve a baggy look of the tunic.

How to modify an existing pattern to draft the tunic?

I bought this pattern from a Czech seamstress. You can take any sewing pattern you have used already for sewing a hoodie. For kids, I like to use basic patterns from this publication (Pattern Making for Kids’ Clothes).

In the image below you can see the hoodie I’m going to work with. It is a fitted one with a standing collar, pockets and a zipper.

Basic hoodie pattern that will be modified to sew a professor Trelawney tunic.

How to adjust the bodice for the tunic

1. Choose a pattern size, that is 1-2 sizes larger than you usually use for sewing garments for yourself. I wear XS or S, therefore I picked M.

2. Get rid of all unnecessary parts of the pattern. These can be collars, hoods, or pockets. All you will need are the FRONT, BACK and SLEEVE pattern pieces. You may keep the facings (if there are any) and adjust them to make them fit the new pattern.

3. If the hoodie is a fitted one with curved side seams (like mine), redraw these and make them straight (see the images below). Make sure that after adjusting, the FRONT and back BACK pieces have the same side seam length. If your pattern has already straight side seams, proceed to the next step.

As you can notice, a small piece of the pattern at the FRONT and BACK is ‘cut off’ at the hem. Do not worry about this, your pattern should be large enough to accommodate your hips.

5. The tunic hem should end above the middle of your thigh and also be shorter than Trelawney’s brown sweater. Measure the length you need to add to the pattern piece to make the tunic the correct length. I added about 15 cm (6”) to the bottom of the FRONT and BACK pattern pieces (see the image below).

6. Horizontally divide the FRONT and BACK pattern piece by adding a style line below the bust-line (see the images below).

7. Develop or modify facings for all bodice pattern pieces: FRONT top, FRONT bottom, and BACK top at the neckline.

At this phase, you should have the following: FRONT top, FRONT bottom, BACK top, BACK bottom, facing for the FRONT top, facing for the FRONT bottom, and facing for the BACK top (see the images below).

How to modify an existing sleeve pattern for the tunic

1. Develop the sleeve cuff. Measure your wrist and add 6 cm (about 3”) ease – this will be the cuff length. When folded, the cuff should be about 2,5 cm (1”) wide – this measurement x 2 will be the cuff pattern width. (see the scheme and image below).

sleeve cuff pattern length = wrist circumference + 6 cm (wrist circumference + 3”)

sleeve cuff pattern width = 2 ⨯ 2,5 cm (2 ⨯ 1”)


Do not forget to add seam allowances to the sleeve cuff.

Sleeve cuff pattern for the professor Trelawney tunic.

2. Measure your biceps circumference and sleeve width at the corresponding pattern part and calculate the amount of ease added to the sleeve pattern.

sleeve ease = sleeve pattern width – biceps circumference

My sleeve pattern has about 8 cm (about 3”) ease. This amount of ease is not sufficient to create the baggy and full look of the sleeve.

I added extra 16 cm (about 6”) to the sleeve ease and width so that it has the proper style. If you also need to add extra width, follow the steps below. The total ease will be 24 cm (almost 10 ”). Keep in mind, that 8 cm (3”) of this amount is included in my pattern already! The total amount of ease should NOT be more than 25 cm (10”).

Adding extra ease to the sleeve is a little tricky. Different fabrics will have different looks. If you have enough fabric, patience and time, I recommend sewing one test sleeve and see, how it looks like.

Adding necessary fullness to the sleeve

1. On the sleeve pattern draw 5 vertical lines along the lengthwise grain dividing the sleeve evenly into 6 parts. Number them from 1 to 6 (see the images below).

2. Slash the sleeve along the vertical lines you have drawn (see the images below).

3. Glue the slashed sleeve parts placing them evenly on a large piece of paper. Calculate the spacing according to the formula below and redraw the sleeve cap (the curved part of the sleeve).

spacing between slashed parts = extra ease/5

In case of this tutorial this will be:

spacing between slashed parts = 16/6 = 3,2 cm   (6 / 5 = 1 1/2”)

Spread parts of slashed sleeve pattern to in order to make a puffed sleeve.

The sleeve pattern is ready (see the image below).

Professor Trelawney tunic puffed sleeve pattern.
Professor Trelawney tunic puffed sleeve pattern.

At this phase you should have all the pattern pieces for the tunic. Transfer them to the fabric.

How to sew the professor Trelawney tunic

How to sew the bodice

Before you start sewing the bodice itself, please prepare fabric for the button loops.

1. Transfer all pattern pieces to the fabric, cut them out and finish seam allowances (see the image below).

2. Underline the facings and finish “outer” seam allowances (see the images below).

4. Sew together the facings and press the seams open (see the image below).

5. Sew together the bodice FRONT (top+bottom) and BACK (top+bottom) pattern pieces and press the seams open (see the images below). Then sew together the FRONT and BACK and press the side and shoulder seams open.

6. Pin and sew the button loops to the bodice FRONT – to the side that will be on your right-hand side when you put the tunic on. Make sure that you position them evenly and sew WITHIN the seam allowance (see the images below).

In this tutorial, I am using buttons with a 1,5 cm (5/8”) diameter, and use 1 cm (3/8”) spacing. The distance between individual button centres will be 1,5 cm + 1 cm = 2,5 cm (5/8”+ 3/8” = 1”). This means that the button loop centres have to be 2,5 cm (1”) apart so that they will match the buttons on the other side of the tunic.

button cetntres spacing = button diameter + space between button edges

button loop spacing = button cetntres spacing

7. Pin the bodice and facing RIGHT sides together and sew them together with a straight stitch (see the image below).

8. Trim away part of the facing seam allowance (see the image below).

9. Carefully clip into the neckline, make sure you do not cut through the stitching. Also, cut away the corners at the neckline (see the images below).

10. Turn the facing towards the inside of the tunic and press. The tunic should look something like this (see the image below).

11. Topstitch the neckline about 2,5 cm (1”) from the edge (see the image below).

12. Fold, press and sew the hem of the tunic (see the image below). It will be a single-fold hem.

13. If you have a fringe trim, pin it and sew with a simple zig-zag stitch using a thread of a matching colour (see the image below).

Now you are going to sew the sleeves.

How to sew the sleeve

1. Finish the side seam allowances and seam allowance at the cap of the sleeve (see the image below).

2. Pin the side seams of the sleeve RIGHT sides together. Mark 15 cm (6”) from the sleeve edge and sew until you reach this marking and press the seams open (see the images below).

3. Gather (or fold) and pin the sleeve edge so that it matches the width of the sleeve cuff. I decided to fold the fabric (see the image below).

4. Sew together the short sides of the sleeve cuffs RIGHT sides together. As you sew, stop before you reach the seam allowance at the long sides (see the images below).

5. Cut away both corners of the cuff on the inside (do not cut through the stitching) and, turn it inside-out to see its RIGHT side (see the images below).

6. Press the cuff (see the image below).

7. On the side, that will be facing your hand, fold the seam allowance towards the inside of the sleeve cuff and press it (see the images below).

8. Pin the seam allowance of the cuff that is NOT folded to the sleeve RIGHT sides together and sew (see the image below).

8. Fold all seam allowances towards the inside of the cuff. Pin, press and topstitch the cuff (see the images below).

9. Topstitch the cuff from the outer side of the sleeve cuff (see the images below).

How to insert the sleeve

1. First, measure the armhole circumference of the bodice. Gather the sleeve cap until its length matches the measured armhole circumference and pin the two together. I use a zig-zag stitch and basting thread to gather.

2. Pin the sleeve to the armhole and sew the sleeve with a straight stitch and remove the threads used to gather the sleeve cap (see the image below).

3. Sew all buttons to the bodice and a button with a buttonhole to each sleeve cuff (see the image below).

Now, the professor Sybill Trelawney tunic is ready! To make a complete professor Trelawney outfit, check out my other tutorials and sew the remaining parts of the costume: the headband, skirt, sweater or leg warmers.

In the images below you can see the complete professor Trelawney costume and all individual parts of it.

Professor Trelawney costume from the Harry Potter movies - ideal for Halloween or cosplay.
Parts of professor Trelawney costume from the Harry Potter movies - ideal for Halloween or cosplay.

Conclusion: How To Sew A Professor Trelawney Costume Tunic

I have to say, I am very happy with the tunic sewing pattern I have prepared for the costume. I think it is quite similar to the original you can see in the Harry Potter movies. The only thing I am not very happy about is the fabric. I just wasn’t able to find one that would be at least a little similar to the one seen on screen. However, if YOU can find such fabric, your professor Trelawney costume will be great!

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