Last year, I ran an email survey: I asked knitters to measure the feet of their friends and family, asking for the following data:
I got nearly 400 replies, providing meaningful data for foot lengths 8.5-11 inches, foot circumferences 8 to 11 inches.
Disclaimer: although I received replies from all over the world, most of the data I received was from North American knitters. I received more data for women’s feet than men’s. There is inherent risk in getting respondents to take their own measurements: I have to trust that they measured in the right place. I don’t claim that this represents every foot in the world, and I don’t believe it should be taken as the final answer on foot size. What this represents is simple: 400 of your best knitter friends offering up measurements of their own feet to help you better understand how to choose a sock size and how to better design sock patterns.
Note: when I mention foot circumference, I mean around the ball of the foot.
I found some interesting results – some confirming what we felt we knew, as sock knitters, others rather surprising.
-In the vast majority of cases, ankle circumference is the same as the foot circumference. The foot circumference is either the same or larger (never smaller), and if larger only by about 5%.
-And there is a remarkable correlation between foot length & foot circumference: foot circumference, on average is about 95% of foot length.
-Gusset circumference on average is larger than foot circumference by 10%. (It turns out that I have a high arch!)
-Heel diagonal about 35% larger than foot circumference, 25% larger than gusset circumference.
-The calf circumference question was an interesting one… lots of respondents questioned why I was asking this. In many cases, 6 inches up from the floor isn’t that far up the sock leg – certainly nowhere near full sock leg length. And this was the point of the question! A standard leg (if such a thing exists) does indeed get wider about 6 to 8 inches up from the top of the heel, where the calf muscles start to curve out – which is also the usual length of a sock leg. But the majority of calf-length sock patterns keep the sock circumference the same – that is, they are assuming that the sock leg doesn’t need any increases to fit comfortably below that calf curve. However, what I learned was that in nearly 50% of cases, there’s a significant increases in leg circumference just up from the ankle.
– Calf circumference 6 inches up from the ground 12% larger on average but there was a huge variance in this – for some, up to twice to size. For 15% of respondents, it’s the same or smaller; 40% it’s 1-10% larger than ankle; for 30% it’s 10-20% larger; for 18% it’s even larger.
WHAT THIS MEANS FOR SOCK PATTERNS
This particular data point was known to me before I started the survey: in fact, it was why I started the survey. Looking at men’s and women’s shoe sizes individually, the difference between the largest and smallest common sizes (e.g. women’s size 5 to 11 and men’s size 6 to 12), there’s a 25% difference in both length and foot circumference. That is, a women’s size 11 shoe is over 20% larger in both width and length than a women’s size 5 shoe; and the same difference exists for men’s size 12 compared against men’s size 6.
Although knit fabric does stretch, you can’t expect one size sock to fit that range of sizes with equal comfort, and to look equally good.
WHAT THIS MEANS FOR SOCK KNITTERS
Rather remarkably, you can guess the rest of the foot measurements based on one: as long as you have foot length, ankle circumference or foot circumference you’re good.
I do recommend you look for sock patterns that come in multiple sizes, and choose the size carefully. Remember that a sock is best worn with about 10% negative ease. Your feet will be happier for it.
WHAT THIS MEANS FOR SOCK DESIGNERS
Socks should be sized!
It is safe to assume that foot circumference = ankle circumference. You can also use foot circumference as rough guide for foot length, as in the formulas above.
Design with a gusset or expanded heel for better fit: If you’re adding a gusset, make it at least 10% larger; if you’re working without a gusset, ensure the heel provides 25%-35% extra circumference.
Allow for larger calves; consider providing suggestions on how to size for larger legs.
I have sliced it two ways: by foot length, reflecting how shoes are sized and how non-knitters tend to think of their feet, and by foot circumference, reflecting how knitters usually think of feet. The numbers are the average of the reported results.
Note: I’m not making any statement here about shoe size, as it’s not an absolute or reliable measurement: I found that for any given shoe size, the reported foot length varied by on average 13%. There several reasons for this: shoe size varies depending on manufacturer (I wear a size 6 in some brands, a 6.5 in others, and a 7 in some others); those with wider feet will more often choose a larger shoe size due to its added width (since relatively few shoe brands provide wide sizes), and shoe size will vary wildly from style to style, and whether a shoe is worn with socks (and handknit vs. storebought socks at that). Just because you buy a size 8 shoe doesn’t mean that you have a size 8 foot!
I hope this is useful to you! If you have thoughts, comments or additional questions, least let us know.
As a reward for reading this far, we have a contest! We’re giving away a pack of 2 skeins of Zauberball to make the excellent and innovative Longitudinal Socks. (That’s enough yarn to make 1 pair of the largest size, or a couple of pairs of the smaller sizes!) Value of the prize is $42. Our usual contest rules apply: leave a comment on this post by midnight EST Wednesday July 18th to be eligible to win. If you’ve won a giveaway in the last year, please give other knitters a chance. Thanks to the Skacel Collection for the prize.