How to choose a size from a sewing pattern

My top tips for measuring yourself and interpreting the size charts

Exciting times! You’ve picked your fabric, decided on what sewing pattern you are going to use, you can visualize the end garment, but….yikes, first you have to pick and choose what size of the pattern you are going to sew!

This hurdle, right at the beginning of the sewing process, can feel daunting and overwhelming. You might be asking yourself ‘What if I pick the wrong size?”, “What if it doesn’t fit?” or you might just be looking at the size chart a bit flabbergasted and not sure what is even going on!

Well you are not alone! Let me help you demystify this step with my top tips for measuring yourself and choosing a size to make from a sewing pattern.

Prefer to hear me chat about these tips? Then check out my latest Youtube video - sometimes it’s easier to take things in by listening to them rather than reading. Or if you prefer to see things in black and white, read on and save this post to come back to in the future for extra help and support!

Key Body measurements

First of all, you will need to measure yourself in a few key areas. You will need a measuring tape. I tend to measure myself in inches as most of the patterns I make have inches listed in the size chart, but if you prefer to work in cm that’s fine too!

  • For greater accuracy, measure yourself in the underwear that you intend to wear with the garment. For me it might be an age thing, or a ‘post having and nursing two babies’ thing, but a different bra can really affect my bust measurement! Measuring over clothing can sometimes give inaccurate larger measurements.
  • The measuring tape should be snug but not tight against your body. Try taking a deep breath in and out, relax as much as possible and then see where the measurement is.
  • If it’s your first time, take the measurement a few times, even on different days or times of the day to check for consistency.
  • Every single body is different and the distribution of shape around the body will be different, for example a hip measurement could be the same for two people but one person could have narrower hips and more shape in the bottom area and someone else could have a flatter shape in the bottom but wider hips. Same goes for the bust, you could have a narrow back and a larger bust, or a broader back and a smaller bust.
  • Regardless of your own individual shape and proportions, these measurements are always the starting point. We will come later to take about how to take into account different distributions of shape around the body.

High Bust

This measurement goes around your body and up and over your bust area.

Full Bust

The measurement goes over the fullest part of your bust. As mentioned above, wear the bra you intend to wear with the finished garment when taking this measurement.


This is your natural waist measurement, typically sitting just below the rib cage. So will likely be above your tummy button.


This is the widest part of your hips and should include your bottom as well.

Working out your dressmakers cup size

The term ‘dressmakers cup size’ is becoming more common now as pattern companies make their size ranges more inclusive.

It’s important to remember that ‘dressmakers cup size’ bears NO relation to regular bra sizing.

It relates to the difference between your high bust measurement and full bust measurement.

Typically if the difference is 2 inches you are a B-cup, 3 inches = C cup and 4 inches = D cup.

Not all pattern companies offer different dressmaker cup sizes with their patterns and if they don’t it's likely that it's been drafted for a B-cup, which is a difference of two inches.

For a more in depth look at dressmakers cup sizes, check out the article linked here and at the bottom of the page.

Finding your size on the ‘actual body measurements chart’

Once you have these key measurements it’s time to check the size chart on the pattern. Some patterns will list the high bust measurement, some will not. If it’s not specifically listed and there is only reference to the ‘bust’ measurement, then it's highly likely that it will be referring to the full bust measurement.

Circle or mark the size chart with your body measurements to see where they are falling. It’s super important to pick a size based on your measurements and not on what size you think you are based on what size of clothes you buy from the shops.

In fact, completely ignore what number the size is called, it could be A, B, C, D, or could be 10, 12, 14, 16….it doesn’t matter. There are a variety of reasons that what the size is called is different to what size you think you are, such as:

  • some patterns use American sizing or European sizing or have their own numerical or alphabetical labelling - all of which will be different to the size you identify with in UK shops.
  • every pattern company is different in that they work from their own unique ‘blocks’ to draft their patterns and each can have different proportions of difference between bust, waist and hip. So even between two different American pattern companies for example, who both use American size labelling, you may still be a different size in each one.
  • just like in some high street shops you may be a different size, in different pattern companies you can be a different size as well.

All of this is NORMAL and it's also VERY likely that your measurements will NOT fit into one of the sizes - don’t panic!

Finding your size on the ‘finished garment measurement chart’

Once you have plotted your measurements on the actual body size measurements chart, you need to then look at the ‘finished garment measurements chart’. This states what size the garment will be once you have made it and will tell you how much ‘positive’ and ‘negative’ ease there is in a pattern.

Positive ease

This is when the finished garment is bigger than your actual body. For most garments made from woven fabric with no elastane or stretchy fibers in them, the finished garment will be bigger that your body so that you can get it on and off, move around in it, reach forward, sit down etc.

How much bigger it is than your actual body will vary depending on the style or design of the garment.

If it's quite fitted then it’s still likely to have around 2 inches of ease, although that can vary, this is just a rough guide.

If it’s loose in style of design it may have lots of positive ease. Think of a gathered skirt or dress for example, the finished hip measurement is going to be loads bigger than your actual hip as the style of the garment is to be gathered a full.

Negative ease

This is when the finished garment is smaller than your actual body. This is most common in garments that are fitted and are made from stretchy fabrics. The fit of the garment comes from the fabric stretching around your body and in order for the fabric to do that, it needs to be smaller than your actual body.

So think leggings or fitted t-shirts.

Some times a garment can have both positive and negative ease at different points in the garment

For example a dress might be fitted at the bust and waist but then be loose over the hips, a bit like the Sew Liberated Stasia dress that is made from jersey fabric.

So once you have plotted your actual body measurements on the chart and can see the rough size range you are falling in, you can then look at the finished garment measurements for those sizes and take that into account when picking a size.

Understanding positive and negative ease can help you choose a size

This is especially when your body measurements don’t all fit in one size. For example if your wait and hips are a different size to your bust but there is a lot of positive ease in the waist and hip area, it could mean that you don’t necessarily have to blend across the sizes and can stick to just making a straight size.

Understanding positive and negative ease can also help you to decide on the fit that you want

If a garment has been designed to be very loose and slouchy and you prefer a more fitted look, you can look at the garment measurements and see if you would prefer to size down. The True bias Marlo cardigan is a good example of this. It’s supposed to be oversized but a lot of people do size down for a more snug look.

You can also check the finished garment measurements for length too. For a top or dress, typically finished length measurements go from the bottom or nape of the neck down the back. Or if you are making trousers then the inside leg seam can give you an indication of the length there.

Some pattern companies go into much more detail and will list the sleeve length, bicep measurement, calf or thigh measurement etc, but this is less likely.

What to do if your measurements don’t fit one size and you think you might need to adjust the pattern

If you have looked at both the body measurements chart and the finished garment measurements chart and still feel that you are going to have to somehow adapt the pattern then there are a few simple things you can try in the first instance.

Bear in mind that the skill of getting clothes to fit is a huge area of learning and one that comes with patience, practise and experimentation. It will be a different journey for everyone and if you enjoy life long learning and development, it's a skill that can be hugely rewarding and satisfying to work on.

How to blend sizes between bust, waist and hip

One simple and easy way to alter a pattern to different sizes over the bust/waist/hips is to merge the size lines between these areas.

For example you might follow the lines for one size over the bust and then move out to a smaller/larger size at the waist and hips by drawing in your own line that connects the two.

Or, in a pair of trousers you might follow one size at the waist and then a different size at the hips. I personally have to do this quite regularly as usually my waist measurement puts me in a larger size than my hip measurement.

Depending on the style and construction of the garment this can often be enough to customize the fit for you. There will be instances where other adaptations are also needed that are a bit more involved, for example, a sway back adjustment, a shoulder adjustment, a bicep adjustment, a full or flat seat adjustment and so on. These are outside the scope of this introductory post and topics that I plan to address in further posts.

How to shorten/lengthen a pattern

All good patterns will have shorten/lengthen lines within their patterns that are lines running horizontally across the pattern at 90 degrees to the foldline (if the pattern piece has one) or the grainline. These lines can be cut or folded to adapt the length of the pattern piece.

If you are lengthening it - simply cut open the pattern and insert a section of paper to fill the gap by however much you want to lengthen by.

If you are shortening it - you can either cut and overlap the pieces or fold along the line to take some length out.

Either way, depending on how much you are altering the length by, you will need to 'true-up' the seams. This describes the process where you just smooth out the edges of the pattern piece if lengthening/shortening has given an irregular edge.

The next steps

One you have chosen a size it's time to cut out and make your garment. The fitting process by no means ends here and will continue as you construct and assemble your garment and try it on as you are sewing it.

You might choose to make a toile, which is a practice garment to test the sizing and fit before you use your final intended fabric.

Join me for my next post all about making a toile, which will cover common questions such as

* Do I need to make a toile?

* What fabric should I use to make a toile?

* How do I transfer changes identified in the toile to the paper pattern?

Happy Sewing!

More articles


Dressmakers Cup Sizes

How to choose the best cup size for you when making your own clothes

Laurens essential Sewing tools

The key items you'll need for sewing your own clothes at home