The Erin Sewalong is a step-by-step video series designed to guide you through sewing the [pattern], from choosing your size to finishing the final details.
In this sewalong, We walk you through each stage of the process in short, focused lessons. You can move through the videos at your own pace, pause as needed, or skip ahead if you’re already comfortable with certain steps.
Erin is your go-to pattern for a pair of chic and versatile trousers. These pants feature a sleek, tapered fit, slash pockets, and a zipper fly with a hook and bar closure at the waist. Tailored to perfection, Erin includes single darts at the front waist and double darts at the back waist for subtle shaping.
Sew these pants in your favorite wovens, like twill, chino, linen, denim, and suiting. Then pair Erin with heels and a cardigan for a dressed-up look or sneakers and a tucked-in tee for a casual vibe.
To follow along, you’ll need the Erin Pattern. Seamwork members can download it as part of their membership, and non-members can purchase it individually in the shop.
Getting Started
Fabric recommendations: For the main fabric, look for medium-weight woven fabrics such as cotton twill, chino, linen, linen blends, denim, and suitings.
Look for lightweight woven linings such as cotton lawn, cotton shirting, cotton poplin, acetate, rayon, or silk for the pocket linings.
Seamwork members, take advantage of your member deals this month! You can save up to 20% off your order here.
Prepare to Sew
This lesson covers all the basic things you need to know to get started with this sewalong. If you’re a beginner, this will be really helpful to watch!
If you feel like you already know how to get your pattern and fabric ready for sewing, go ahead and skip to the next lesson and you'll learn to do some helpful fitting adjustments.
You're going to learn how to:
- Select a pattern and reference its skill level
- Select a size
- Prepare patterns and fabric
- Cut and mark fabric
Fitting Adjustments
In this video, you’ll learn some helpful fitting adjustments for the Erin trousers.

Thigh Width
If you notice tight wrinkles across the thighs, you need to increase the width at the thigh. If you notice excess fabric hanging vertically at the thighs, you need to decrease width at the thigh.
Crotch Depth
If your muslin’s crotch point is sitting uncomfortably high or hanging too low, you need a crotch depth adjustment. You can also adjust the leg length to suit your personal preference.
We created a free downloadable PDF called the Four Height Zones to help you gather the information you need to make adjustments to your pattern where you need it. We recommend printing it out and writing your height measurements on it to keep in your sewing journal.
Compare these measurements to the corresponding landmarks on your pattern pieces, and you'll know how much you need to shorten or lengthen that part of the pattern.

And here are some additional fitting resources if you need them:
- Follow this tutorial to lengthen and shorten a sewing pattern
- Pants Fitting Basics
- Learn some pants fitting basics.
- Seamwork members learn all about pants fitting, including crotch depth adjustments, full belly adjustments, thigh adjustments, rear adjustments, swayback adjustments, and balance in this video sewalong.
- Understanding ease will help you pick the right size or sizes. This tutorial will teach you all about design and wearing ease.
Sewing Instructions
The PDF instructions will be your main guide as you work through this pattern, but we've created this video to walk you through the trickiest steps in detail. If you need help on a step not shown in this video, check out the Community Group Sew, where other Seamworkers and staff are ready to help out!

The trickiest steps for this pattern are:
- Sew zipper fly (01:47)
- Attach facing (19:17)