Pattern Adjustments for the Petrichor Pinafore

Petrichor Pinafore sewing pattern

Our newest pattern, the Petrichor Pinafore, is an easy, loose-fitting overdress with an uncomplicated style. Even so, some people might need to fine tune their fit a bit!

For me – short and busty – a few simple fixes delivered a lot in terms of wearability. Even if you need none of the following adjustments, getting the straps in the right place for your body can be done while sewing. We always recommend making a muslin test garment, and in this case that might be a wearable muslin just to perfect the straps. When fitted correctly, the arm openings should scoop down to your natural waist – or just above – and often this can be done just by shortening or lengthening the straps.

I used quilting cotton for my wearable muslin, and while that was ideal for a bit of stiffness while fitting, I’ll be making my final Pinafore out of a beautiful linen gauze! This test will be used for pj’s or in my dye studio – the recommended fabrics have much more drape. I’m also looking forward to shortening it to just under the pockets to wear tunic length.

I’ll demo shortening or lengthening straps at the end of this tutorial, so if that’s all you need just skip to the end!

Straps aside, the three adjustments I’ll be focusing on are front yoke gaping, adding a bit of bust shaping, and side seam angle.

Please note: these adjustments were made with a test version of the pattern – the final pattern might vary slightly from what is shown here.

To make these adjustments, you’ll need some tools!

  • Petrichor Pinafore test muslin
  • Petrichor Pinafore pattern
  • clear ruler
  • mechanical pencil
  • clear tape
  • curved patternmaking ruler (optional but nice!)
  • eraser
  • paper scissors

We’ll start with the front yoke adjustment. If you have more narrow shoulders and/or a larger bust / chest, this might result in some gaping at the center of the yoke. With your muslin on, pinch & pin the excess fabric until it lies flat, This adjustment is for alterations up to 3/4″ (1.9cm) total – any more than this, consider going down a size or two on the top of the pinafore then blending between sizes for the lower portion.

Measure the amount you’ll need to adjust. I have 1/4″ (6mm) here, on the fold – so that will be removing 1/2″ (1.3cm) altogether. And a reminder to mark your size notches for visibility before you cut out your pattern!

Fold the front yoke in half to mark the center & draw it in. At the top & bottom of the center, draw in the seam allowance – 5/8″ (1.6cm). On the top seam allowance line, mark your adjustment on either side of the center – again, mine is 1/4″ (6mm) for a 1/2″ (1.3cm) total adjustment.

Draw in cut lines from the adjustment marks to the bottom seam allowance intersection, then cut this triangle out. Make a snip from the bottom point up to the seam allowance intersection, leaving a small hinge of paper uncut – this will allow the new edges to be taped together smoothly. Tape the edges together! Tape some extra paper under the bottom snip to fill it in & redraw that bottom point. I also smoothed out the top edge into a bit more of a curve with some extra paper and my curved ruler.

Next on the list is some shaping at the bust! If you tried your pinafore on and have a little gaping at the side where the arm opening meets the yoke, this adjustment will help smooth that area. If you normally make a full bust adjustment on garments, you might notice this gaping.

Try your test muslin on and pinch out the amount needed to make it look smooth – again, this is a minor adjustment and I would keep it 3/4″ (1.9cm) or less total. My pinch measures 3/8″ 91cm), and that’s 3/4″ (1.9cm) in total.

On the arm edge, measure down the full amount you are removing. Draw a line from this point to the dart for your size. Use a curved ruler to smooth out the line, then trim off the excess paper. Usually I do adjustments on the sewing line, but the length of this adjustment changes very minimally so we can get away with a bit of a cheat (shhh!). A reminder that the arm bias will be now longer than the arm edge, but you can just trim this after sewing. The instructions for stitching the Front to the Front Yoke do not change.

Let’s take a look at our side seam. I love the fullness at the hips & hem on my muslin, but feel that the waist is too big for me. It’s normal for me to pick a smaller size at the waist and a larger at the hip, so this was no surprise.

I pinned up what felt comfortable and measured a 1″ (2.5cm) pinch, so I’ll remove that amount from both the front and back side seams. I’d say around this amount is the maximum you want to take out for this adjustment – removing more than this means the angle of the hem will also need to be adjusted.

Starting with the Back at the join of the arm edge and side seam: measure in the amount you pinched (1″ or 2.5cm for me) and mark. Draw a line from this mark to zero out at the hem, then trim the excess paper. Set the Back aside.

On the Front, measure over your amount (just like on the Back) and draw your new line from this mark to zero out at the hem. Don’t worry about skipping right over the pocket opening – that’s next!. After drawing your line, align your clear ruler with the top point of the pocket opening. Draw a line perpendicular to the new side seam line, this will be the new top of the pocket opening. Using your Pocket Facing pattern piece, place it on your new line so the top of the pocket opening matches your mark for where the new curve starts. Trace the opening curve and highlight it so you can see where to cut, then trim the excess paper.

And lastly, a quick bit about shortening or lengthening straps. There’s a shoulder line on the pattern that we can use as a starting point – this is important so the angles at the strap front & back are maintained, along with the back notch.

I decided to shorten my straps 1 1/2″ (3.8cm) in total. I marked half that amount (3/4″ or 1.9cm) on either side of the shoulder line, then folded the two new lines to meet. Tape on both sides.

If you need to lengthen your strap, you’ll need an extra bit of paper. Draw two parallel lines on your extra paper the amount apart that you need to lengthen – the pictures show lengthening by 1″ (2.5cm). Cut your strap at the shoulder line and tape one side to match with one new line. Tape in place, then extend the grainline to match up the other side of the strap. Tape this, then draw in new cutting lines at the side edges of the strap. Trim off excess and you are ready to cut fabric.

I hope this helps you to fine-tune the fit of your Petrichor Pinafore! I’m really looking forward to wearing mine all summer, and can’t wait to see what everyone makes.


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  1. Thank you! I’m short too! Another adjustment I’d be interested in would be to have smaller arm holes so it wouldn’t expose my midriff

  2. Thank you! I have narrow shoulders and back, but a postpartum belly that always bumps me into a larger size bracket. I’m currently 40-38-45, which would have me in a 16 for the bust but an 18 /20 for the waist. Given the pattern ease, could I get away with Making a 16? Or should I grade up in the skirt and make a 16/18?

    1. Hi Bethany, I think because of the ease you would be fine to make the 16. Take a look at the finished measurements to be sure, but that should give you about 17 inches of ease in the waist which will be very drapey and nice. Feel free to email us if you need further fitting advice, we are happy to help! Use