converting measurements in knitting patterns

Almost weekly, my colleagues and I are asked questions, from both designers and knitters, about converting measurements in knitting patterns, and why we advise the way we do. The simple answer is that gauge is given over 4 inches and 10 centimeters, which is a 2.5 ratio, so we must use that ratio when we convert to be correct. But since it can be confusing to folks, let’s really get into it.

In knitting patterns, we convert between the two measuring systems, metric and imperial, with a 2.5 ratio, whereas in reality, 2.5 cm does not equal 1 inch; 2.54 cm equals 1 inch. Yet when it comes to converting measurements in knitting, we use a 2.5 ratio – ‘we are less accurate to be more precise,’ as fellow tech editor Tabitha Dukes says in her excellent article on this subject, which I recommend you check out. This concept trips up a lot of knitters and designers, because it just goes against our natural instinct to get things right, but the reason we do this is actually simple and brilliant, and the best way to get things right.

Gauge matters.

Not surprisingly, the reason is all to do with gauge. In almost all knitting patterns, gauge is given over 10 cm and 4 inches. That is a 2.5 ratio. Gauge is not given over 10.16 cm and 4 inches, which is a 2.54 ratio. Because gauge is given with a 2.5 ratio, meaning that the pattern was designed with a 2.5 ratio, then for knitters to get the lengths and widths they need, that they swatched for, they must use this base ratio, and designers must be sure to write their patterns this way, since they have given the gauge this way. If patterns were written with gauges given over 10.16 cm, we would all have a hard time measuring these small uneven measurements in our knitting. Don’t let that make you think these small differences don’t matter. When you multiply this .04 difference over all the stitches and rows in your item, it makes a big difference indeed. If a knitter swatches a 10 cm gauge, gets your numbers, but the pattern has been converted with 2.54, the knitter will not get the promised finished measurements, because your gauge is at a 2.5 ratio. So, the gauge given over 10 cm determines the widths and lengths in the pattern, not what it would be over 10.16 cm. If you give gauge over 10 cm and 4 inches, that is a 2.5 ratio, so you must convert with 2.5.

As a knitter, think of it this way: stop comparing the two systems, get that relationship between inches and centimeters out of your head. It doesn’t matter. If your gauge is based on a 10 cm square, you proceed with the pattern working in centimeters, following the instructions, and you will get the size promised in the pattern. If your gauge is based on a 4 inch square, you will follow the inches in the pattern, and get the promised size. Your measuring tape does not matter. What matters is what system you are working in. If inches, then you can only look at stitches and rows over 4 inches; if working in centimeters, then you can only consider stitches and rows over 10 cm. You can't jump between systems - you have to stay in your measurement system. This is how your gauge is described, and this is what your measurements are based on.

Being accurate: an example.

It's not accurate if you are looking at a ruler or measuring tape and comparing measurements. But if you measured your swatch in a particular system, it is absolutely precise. So, because gauge is given over 10 cm equals 4 inches, using a 2.5 ratio, we must convert that way throughout the whole pattern to get the correct lengths and widths. If we use a 2.54 ratio, the numbers we got with our gauge swatch will not be what we end up with in our knitting, and we will be upset.

Consider how this plays out – let’s do some math: If you chose to use 4”=10.16 cm (1"=2.54 cm) for your sweater pattern, then the entire pattern needs to be written that way and your metric knitters would have to measure their swatch to the 10.16 cm, not 10 cm, which is difficult. If you list the gauge as stitches/rows over 10 cm, all the measurements need to be based on the 1"=2.5 cm ratio. If you convert measurements using 2.54, then the knitter will be frustrated because their measurements will not be correct, because it is not based on the gauge, as you can see below:

Gauge says 20 sts/24 rows = 4" or 10 cm
Your knitter gets gauge and their swatch measures as you list.
If you tell them to work to a 15" body length (and convert then with 2.54, which would be 38 cm), their piece will be half a centimeter longer than what the gauge is based on (37.5 cm). It is a small difference, but exponential as the sizes get larger. They will also use more yarn, in any size, because in some gauges, that difference is 1-2 more rounds/rows.

With bust circumference (especially in the larger sizes), at the same gauge, a 62" circumference = 310 stitches. If you convert with a 2.54 ratio, your schematic would list those 310 stitches measuring 157.5 cm, but their actual sweater on the needles will only measure (according to the 10 cm gauge) 155 cm, which is a whole inch less, and the knitter would think they did something wrong or that their gauge was off. They would also end up with a sweater the wrong size, and that would be bad.

Keep it simple.

Simply, if your gauge is given as 10cm=4 inches, in a 2.5 ratio, the pattern must be written to that ratio, and the measurements must be converted that way, to ensure your knitter gets the measurements you promise. Don’t we always say, gauge is everything? You see, converting the two systems with a 2.54 ratio actually will be an error, cause mistakes, and not get the knitter what you intended at all, and will make them grumpy. Converting with 2.54 will not make the pattern more accurate or correct, it will actually make it wrong.

using fixed ease

I am a knitting technical editor, and part of my job is checking that the finished measurements of a garment offer the same ease across all the sizes in the pattern (this is called fixed ease). Ease in garments is simply the space between the garment and the body. Making sure all sizes offer the same ease as the sample size is how we maintain design integrity, and ensure proper fit for all the sizes, so that the garment will fit the same way in every size as it does in the sample it was designed on.

Proportionate ease (sometimes called relative ease) is a concept that says the ease should change from size to size, increasing as the sizes increase. For example, a garment that allows 3″/7.5cm of positive ease for the 30″/75cm bust size would need to allow 6″/15cm positive ease for the 60″/150cm bust size. Let’s dig into this. Should we apply the same ease across sizes in designing garments, or grow the ease proportionately as the sizes grow?

There are three different things at play here:
1. Design integrity, proper fit
2. Knitter preference
3. Designer assumptions

What needs to happen.

To maintain the same fit across sizes, and not alter the intended design, so that the garment will fit and drape the same on a smaller body as it does on a bigger body (not based on your opinion of how that looks, but actual fit), the ease applied needs to be the same across sizes in all the points on the body.

While the proportionate ease concept may make sense in other areas, for fitting bodies, it just doesn’t work. One reason for this, is that when you change the ease across sizes of say, the bust, it then in turn alters the fit in other areas of the garment, like the neck and the sleeves, and completely changes the fit, even the structure and style, of the whole garment. Every part of the body needs to be considered in designing garments, and each part is connected to another part, and they must each reflect the ease of the sample for a good fit. To see a great comparison of fixed ease vs. proportionate ease (or relative ease), see this article by Julie Robinson.

Take, for example, a garment that is intended to have only 1”/2.5cm of positive ease: this means that the body measurements are very nearly the same as the finished garment measurements. So, on any-sized body, the garment would be need to be nearly the same size as the body, and that is the only way to get the intended fit, which is a near skin-tight fit. If proportionate ease were applied, and inches/cm of ease were added as the sizes got bigger, the sweater would not fit the same, nor look the same at all, since the only way for it to be near skin-tight is for there to be nearly no ease. This same example applies for any garment.

Even if the body is bigger or smaller, more or less ease than the sample will alter the way the garment will drape and look on that body from what it is designed to be. Good fit is the goal, and the fit of a garment has nothing to do with how big or small the body wearing it is – the body can be any size; fit has all to do with the relationship between the outside of the body and the garment. This is the ease, and it determines the fit. The size of the body makes no difference in determining how much ease is applied when working with zero or positive ease.

So, knowing this is true, it is our perceptions of what ‘looks good’ on different body sizes, and preferences of how individual knitters like their clothes to fit, that gets us to ask this question: should we apply proportionate ease?

Mods are not the promise.

Different garment shapes will look different on different body shapes, to be sure, as some people have squarer shoulders, slighter arms, wider hips, and each lend themselves to particular garment styles, and that is the knitter’s choice, what style of sweater they choose to make. But the style they choose should offer the same fit across sizes, the same drape and the same room, as the sample and as the picture (this is your promise to the knitter, this picture and sample).

Any less ease applied will make the garment fit more tightly, and any more ease applied will make the garment more roomy than intended. Most patterns suggest recommended ease, that reflects the pattern photos, so the knitter knows what they are getting. Sometimes instructions are offered for how to modify certain parts of the design to add or subtract ease or length, and that is the knitter’s choice, but is not the base design. We all have individual preferences of how we like to wear our clothes and how we like things to fit, which is awesome, and so being able to make modifications to a pattern you are knitting is great.

Sometimes you modify, sometimes you don’t. If the knitter wants more or less ease than what is shown, they can make those adjustments as desired, however, the pattern (and therefore the designer) must maintain the integrity of the design, so that what is promised in the pictures and descriptions is what the knitter will get if they follow all the instructions.

The pattern should maintain the same fit and ease across sizes, and that’s what grading is. That is why, while your design features and elements are often your priority and maybe what you value most about your work, what knitting designers are doing is designing clothing to fit all bodies (hopefully!), so the size grading is also a big part of the creative process of designing – thoughtful attention to fit, referencing sizing charts and feedback from knitters, and being cognizant of how and where bodies change across sizes, is necessary for good grading, and being sure your garment will fit as intended, before any knitter modifications.

The big mistake.

The third thing is designer assumptions. We all have opinions about what looks good and what doesn’t, about how we and others ‘should’ dress. The thing is, how others dress is simply not our decision, nor our business. Of course, we know that. And yet fatphobia (the idea that fat is bad and thin is the ideal) works on all of us, thin or fat – it is ingrained in our culture and in our every day, and as a result, certainly influences how we design clothing.

Because of this, over time, we have incurred some misconceptions:
- That fat people should wear loose clothing, that fat people don’t look good in well-fitting garments.
- That often fat people feel they should hide their bodies in their clothes, that they don’t ‘look nice’ when things fit well.

These things simply aren’t true things – they are borne out of the idea that fat bodies are not attractive bodies, and so should not be shown. It has no basis in anything valid, and is a total fallacy, yet it informs decisions about designing for bigger bodies. It makes us ask this question (should we apply proportionate ease?), when we know that applying the same ease across sizes is how to maintain intended fit. These assumptions, that fat people need more ease, or need more room in their garments than thin people, or that oversized garments should only exist for thin people, is borne out of fatphobia, and is the cause of a lot of hard hours of knitting resulting in ill-fitting garments.

In our current culture, fat people are often made to feel that if something doesn’t fit as promised, it is their fault, when in fact, it is not! This applies in both directions (applying proportionate ease is only one problem): many patterns claim to be size-inclusive when they aren’t, if you look closely – for example, if you have a garment that recommends 10″/25cm of positive ease, and claims it fits up to a 60″/150cm bust, but the finished measurements of the largest size of the garment are 60″/150cm, then it is off by about 10″/25cm, and the pattern is lying to the knitters.

The promise.

The sample size of the pattern, and the size that is pictured when you purchase a pattern, is what is promised to the knitter if they work the pattern as instructed, so that must be delivered on for all sizes, or the pattern is misleading knitters. That promise is kept by applying fixed ease, the same ease across sizes. If you feel fat people shouldn’t wear close-fitting clothes, or that your recommended ease doesn’t count for fat knitters in oversized garments, then ask yourself, why do you think that? Why do you think fat knitters want extra fabric than is intended in their garments, or want them to fit differently than a thin person would? Do you come up with any reason beyond prejudice against fat bodies? Ask yourself these, and more, questions. Be sure when you are designing, that your choices are purposeful and intended.

Tune out the noise.

We are so accustomed to seeing thin bodies modeling every design (even in catalogs of plus-sized clothing!), that we don’t think it ‘looks right’ when we see that same design for a bigger body on that body, or laid flat, but that is only because we are not accustomed to looking at fat bodies in a positive way, or thinking that they can look good (when of course, they do – hello, fallacy). That is an error in judgment, and a prejudice we must overcome, especially as designers of clothing for all bodies.

Instead of changing the way we grade garments, and allow for proportionate ease, when we know what it means to grade designs for good fit, we need to change the way we model designs, change the way we think about bodies, stop letting societal prejudice inform grading.

Show up for your knitters.

Model your designs on as many sizes as you can. Hear, hear for all designers showing their designs properly graded on fat models – more of that is what we need. And thanks to all designers thinking thoughtfully about fitting fat bodies and taking care to realize that not all body points grow at the same ratio (this is very important, knitters with a vast difference in bust size can have nearly the same wrist size, for example), and that well-fitting garments are possible for all body sizes. Let us also please acknowledge that knitters are individuals of many sizes, whose preferences vary, and so please do supply them a schematic with the measurements of the garment so they can choose a size based on their preferences and size, grade your patterns applying the same ease across sizes in all the points on the body, and if possible, show your knitters your design on different bodies.

It is not the job of designers and tech editors to alter designs from what they have promised the knitter will get when they buy it, so that it fits them differently. Good fit: this is what we are aiming for in our jobs. Our goal is to achieve the same fit across sizes – maybe not always simple, but always worth it. There are many resources out there to help us get this right. Let us remember that what we are creating is clothing, to fit all people, and people come in many sizes, and all bodies deserve well-fitting garments. It is not for anyone to say that these garments shouldn’t fit as well on fat bodies as they do on thin bodies. And when we apply proportionate ease, that is what we are saying.