When maing a sling for yourself, there are two factors to consider: your size (and/or your partner's size), and the length of the tail you'd like.
The following chart data come from measurements done on real people wearing a real baby and sling. If your build is not on the chart, don't worry! Weight is more important than height in picking a sling size if your weight is proportional to your height. If you are tall and thin you will probably want a smaller sling for your weight, and if you are short and heavy, you'll probably want a longer one.
Measurement | Finished sling length for tail to end at... | |||
Weight range | Height range | Hip | Mid-thigh | Knee |
125 lbs & under | 5'4" and under | approx. 62" | 65" (xs) | 70" (s) |
115 to 130 lbs | 5'4" to 5'7" | 65" (xs) | 70" (s) | 75" (m) |
130 to 150 lbs | 5'5" to 5'8" | 70" (s) | 75"(m) | 80"(l) |
150 to 200 lbs | 5'6" to 5'9" | 72" (s/m) | 80" (l) | 85" (xl) |
200 to 260 lbs | 5'7" to 6" | 80" (l) | 85" (xl) | 90" (xxl) |
over 270 lbs | 5'8" to 6'2" | 85" (xl) | 90" (xxl) | 95" (xxxl) |
Measuring yourself: Take a long tape measure, or a piece of string, and wrap it loosely around you the way a sling will be worn: start at corsage position (where the flowers are shown at left), bring it around your opposite side at about the level of your natural waist, around your back to the same shoulder, and then let it hang down from the corsage position (NOT the top of your shoulder -- this will make the measurement too long) to whatever point you would like the tail to end. If you measure with the tape tight around you, add about 4 " for the baby. If you find, however, that the measurement you get is significantly different from the table above, I would err on the side of the table; measurements done in this manner seem to be consistently 6-10" too long, from what people are emailing me.
This measurement, combined with some basic information about your height and build, can help us figure out what size to make. Please keep in mind that due to variances in the fabric's thickness and stretch and the ring thickness, none of the measurements are exact, and when you're wearing the sling, the length of the tail will vary depending on the position the baby's in and how many layers of clothing you're both wearing. It's not an exact science, and a variance of +/- 5" is not going to make the sling unusable; plus, the "ideal" tail length is highly subjective, and you may find that you prefere a long, glamourous tail, or a short, out-of-the-way one, rather than mid-thigh length
If you're buying fabric online, most places will sell in either 1/2 yard or 1 yard increments. That means that if you figure you want a size medium sling, you'll probably have to buy 2 1/2 yards of fabric anyway, and from some sites, 3 yards. If you're buying in person at a fabric store, I would err on the longer side for several reasons: one, fabric shrinks when it's washed and dried, so you'll need to get more than you think anyway; two, you'll need extra fabric for sewing in the rings -- more on that below; and three, if you make a mistake in sewing, sometimes it's easier just to cut off what went wrong and start fresh, which is a lot easier if you have more fabric to work with.
If you read the shoulder styles page, you'll see that each shoulder style uses a different amount of material when you're sewing in the rings. The kind of pleats I do, for example, are most comfortable when the stitching line for the rings is no more than 3" from the rings (I do about 2.5"), which means that I need 3" extra material to get the finished length of sling (e.g. to make a 75" sling, I need 78" of material). If you're doing a plain gathered shoulder, I would sew no less than 5" from the rings, which means you'd need 5" or more of extra material -- for a gathered shoulder, I think even more than that is best, like 8-10". Keep this in mind when you're purchasing fabric.
In short, since you're making the sling for yourself or someone you know, I think it's best to start with about 2.5 yards and work from there. Once you've found a comfortable shoulder style and tried on the sling, you can hem it to the length that feels best to you -- there's really no need to cut it to length before you sew in the rings. If you're petite, obviously a finished sling length of nearly 2.5 yards is going to be enormously long, and you'll end up with quite a bit cut off. You can use that to make a pouch to store your sling in, or any number of matching accessories. If you're more plus-sized, you may feel comfortable with a finished length of 2.5 yards and that's fine!
These widths refer to the finished width of the sling, after hemming. Hemming will usually take up between 1/2 - 1" per side. Most slings are between 26 and 32" wide, although you can make a wider one if you'd like more support for a very heavy baby or a taller toddler or preschooler. The width is mainly personal preference, although there are some general guidelines based on fabric weight that you may also take into account. In general, if you're using a lighter fabric, like a lightweight twill (which is still sturdy enough for a sling) or dupioni silk, you may wish to go with 32", or even wider if you have a tall child. For thicker, heavier fabrics (like tablecloths, printed duck, or wrap materials), 26" will usually be sufficient. If your fabric is heavy and wide, it will be very difficult to thread and adjust in the rings, which can easily make it unsafe. The majority of medium-weight fabrics (like 5-6 oz/yard linen, lightweight denims, and osnaburg) are fine anywhere within that range.
I do not recommend using a ring sling that's less than a bare minimum of 25" wide. Less than that and you will likely find it very difficult to make a good seat for your child, which can be unsafe, especially if you're a new user. Your sling should enclose your baby from the back of her knees all the way to her shoulders at minimum, and it's most comfortable if there are several inches to spare, which you can gather up behind her knees to create a little padding. Please watch the video here for tips in adjusting the sling and getting a good seat.
NB: The width and weight of your fabric will determine the ring size you choose. I usually recommend medium rings for widths of 26-29" (assuming a medium-weight fabric) and large rings for over 30", but if you have a heavy fabric, you will probably need large rings regardless of the width.
If you're hoping to share a sling with a female significant other, it's very likely you can both wear her size unless there is a large disparity in your builds. A size small will, generally speaking, be long enough for most average-sized men; you will likely end up with a hip- to upper-thigh length tail, which most men find quite sufficient. A medium, on an average-sized man, will be upper- to mid-thigh length; and a long is generally mid-thigh to knee-length. If you are extremely muscular through the shoulders, or, on the other end of the spectrum, built for comfort rather than speed (i.e. you wear a larger than XXL shirt), you may want a size long, but a medium should do just fine; it will just have a shorter tail. As long as the tail is longer than 10-12", it is safe; it can be tucked in around the rings or into the body of the sling if you don't like the look of a dangling tail. For the most part, unless your partner wears an XS sling, you probably won't need a longer sling than she does. (Oh, and if you're on the fence about babywearing, remember that there's very little that women find sexier than a man who can care for a baby! Trust me, you will get all kinds of positive attention if you're wearing your baby in a sling.)
If you are a woman sharing a sling with another woman, or a man sharing with a man, I would suggest a size to fit the larger partner. The smaller partner can tuck the tail into the body of the sling or wrap it around the rings as above. However, if there is not a large size disparity, a size between partners is fine, or if the larger partner would prefer a shorter tail, a size for the smaller partner is fine. It's really all up to personal preference.
In my business, most of the orders I get are for medium slings, and I think that's true for most manufacturers. After that comes small, then large.
I am 5'11" tall and when I used to weigh 260 lbs, with a shirt size of between 22 and 26 (2x or 3x), depending on the brand, I preferred an extra-long (85") sling, which came to mid-thigh on me when worn with Susan in a hip carry. A medium sling went to my hip, and short (70") to my waist. XXL (90") went down to my knees. I currently weigh around 200, and prefer a medium (75") sling, on those rare occasions that Susan wants to go in a sling (she's 4 now). A long sling is now nearly knee-length on me.
My sister is 5'4" tall and weighs about 125 lbs, and she wears a size 6-8 or thereabouts. A short sling goes about to her mid-thigh, and extra-small goes to her hip; that's with Susan in a hip carry. A medium sling goes to her knees, and my long sling was almost to her ankles.
A friend of mine wears a size 32 or so, and a medium sling went about to just below her hip. The XXL was closer to mid-thigh, and XXXL was knee-length. It's a very rare person indeed who really needs that much length, in my experience.
Using a long ring slings for ruck-under-bum back carries: I do not personally recommend using a long ring sling to do this style of carry, and must completely disclaim any liability for incidents that occur when using this position against my recommendation. Back carries, especially those done with infants, are inherently more risky than front carries, whether you've been using a sling for a week or for years. I would encourage you to get comfortable with front carries first, and if you want to do back carries, purchase or make a short wrap for that purpose, rather than buying an exceptionally long ring sling to do it. If you would ordinarily wear a size medium, but purchase an XXL sling so that you can do ring sling rucks, and then you find that you are only using the sling for front carries anyway, the tail is going to be super-long, and that's a tripping hazard. I know this is a very popular idea right now, but it's really recommended only for experienced, seasoned babywearers, and I must discourage you in the strongest terms from doing this carry -- or for purchasing a too-long sling for the purpose -- if you are a new user.