In the world of sewing and pattern cutting, seam and hem allowances play a crucial role as they serve as the finishing touches to complete your self-drafted sewing patterns. It's important to handle them with care, following the guidelines below.
Always remember the golden rule: Seam and hem allowances are the last guests to arrive at the party! 🎉🧵 They come in after you've made all your design decisions, whether it's a single adjustment or a series of changes. Adding seam and hem allowance should be the last thing you add to your sewing pattern and you should never change them or add extra bits of design features to them.
If you're uncertain about which type of hem or seam to choose, take a look at the tables below. They'll help you make the right choice for your design and fabric.
Ultimate Guide to Hem and Seam Allowances
Mastering Seam Allowance Guidelines
Plain Seam (the seam most commonly used) Seam allowance required: 1cm or 3/8" Plain seams are either pressed with the raw edges open or facing toward the back of the garment.
French Seam
Seam allowance required: 1.5cm or 5/8"
This technique is often used on lightweight fabrics that fray easily. You may use it when you desire a beautiful finish on a silk shirt.
Double Stitched Seam
Seam allowance required: 1cm or 3/8"
Good for knit fabrics to stop the fabric from rolling but can be used on woven fabrics too
Flat-felled Seam
Seam allowance required: 1.5cm or 5/8"
Traditionally, this method is used on the inside leg seams of jeans.
Here is a flat-felled seam on a pair of jeans.
Bound Seam Seam allowance required: 1.5cm or 5/8" This seam is great to use on coats or jackets that don't have a lining.
Here is a bound seam on the inside of a sleeveless overcoat I made.
Want to listen to a detailed explanation of various seam allowance guidelines? Check out my YouTube video here.
Hem Allowance Guidelines: Crafting Neat Finishes
Double Fold Hem Hem allowance required: 1.5cm or 5/8" This is the most common hem, as it hides raw edges and prevents fraying
Narrow Rolled Hem Hem allowance required: 0.6cm or 1" Great for light fabrics, especially silk, and for finishing curved edges (you can get your hands on sewing machine feet designed to assist with this process).
Ignoring the cream elastic, here is an example of a narrow rolled hem I used to finish my bamboo silk top.
Here is our favourite tutorial by Daria Pattern Making on how to sew a narrow rolled hem/baby hem https://www.instagram.com/reel/CgCVI1ZqhTA/
If you're keen to jazz up your rolled hems then try this method below...
Blind Hem Hem allowance required: 2cm + or 1 1/2" A hem that is often used on trousers, skirts and curtains.
Zigzag/ Overlocked Hem
Hem allowance required: 1.5cm or 5/8"
Another frequently used seam, which results in less bulk compared to a double fold, requires only a single fold due to the zigzagged raw edge.
Here I used an overlocked edge to finish the bottom of the facing inside a dress I made. If you were to do this on the bottom of the dress you could then use the overlocked hem to finish the look.
Knit Hem Hem allowance required: 1.5cm or 5/8" A long, narrow zigzag stitch is used with stretch fabrics to prevent thread breakage while allowing for stretching.
***Keep in mind that when working with thick fabric, larger hem allowances will be necessary***
Want to listen to a detailed explanation of various hem allowance guidelines? Check out my YouTube video here.
TOP seam and hem allowance TIPS to take away today...
Always add hem and seam allowance last.
If you ever need to make adjustments to a sewing pattern, be sure to mark the locations of the hem and seam allowances. This way, you can avoid altering them by accident. If necessary, you can always trim them off and then add the hem and seam allowance back in later.
Make sure to mark any notches accurately across your seam allowance using your pattern ruler to ensure precision.
Press as you go! Ironing and pressing your seams and hems as you sew will give your project a professional finish.
You can really make the seams and hems a key future on your garments to add extra flair and show off your skills. Check out our inspiration from Pinterest below to get your creative juices flowing...
Download the hem and seam allowance charts inside my FREE eBook below...
Get more from your sewing projects and release your creative potential in pattern drafting and dressmaking!
Grab your FREE copy of my eBook, 'An Introduction to Pattern Cutting', to learn how to start creating sewing patterns for clothes you love. Learn the basic foundations of pattern drafting, discover a list of essential pattern cutting toolsyou need, learn more about pattern blocks/slopers and so much more.
Take a peek inside! ⬇️
Happy sewing,
Sarah x
P.S. I'm a real person and we have a fabulous team here behind the scenes eager to help❤️. Feel free to send us a DM on Instagram or an email to hello@thesewingretreat.co.uk if you have any questions, We'd love to hear from you :)