# Why are there two difference knitting needle measurements? **URL:** \ **Category:** Factual Questions\ **Created:** [September 18, 2006, 3:28pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182 "2006-09-18T15:28:25Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Shirley\_Ujest](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shirley\_Ujest](https://boards.straightdope.com/u/Shirley_Ujest)\ **Post date:** [September 18, 2006, 3:28pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182/1 "2006-09-18T15:28:25Z")
Size 8 needles (us) are size 5 MM for, apparently, the rest of the world. Why can’t the Knitter’s Mafia/Union/guild/grannies of the world get together and just agree on One Unit of measurement and why is there two to begin with anyways? If this is the wrong forum, I apologize, but it is a Burning Question for me as of late. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [September 18, 2006, 3:35pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182/2 "2006-09-18T15:35:15Z")
Prob’ly the same reason that our roads have miles and everyone else has kilometers, our gas has gallons and everybody else has liters, our beef is in pounds and everybody else uses kilograms, our tools are in inches measured with denominators that are powers of 2 and everybody else has millimeters. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [September 18, 2006, 3:37pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182/3 "2006-09-18T15:37:46Z")
Or, as a Britisher told a roomful of stunned Amurkins: “if we had to convert out of Imperial and survived, can’t see why you darned colonials can’t bother!” The numbers are a “sizes” system similar to clothing… there was a reason behind them once, but it’s lost in the mists of time (like for clothes). The MM are actual millimeters. ---
**Author:** ![Shirley\_Ujest](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shirley\_Ujest](https://boards.straightdope.com/u/Shirley_Ujest)\ **Post date:** [September 18, 2006, 3:40pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182/4 "2006-09-18T15:40:09Z")
Well, I knew the MM were metric, and I have no problem going over to the Dark Side of stuff like that there, but why can’t everyone just get on the same bus? ---
**Author:** ![DanBlather](https://avatars.discourse-cdn.com/v4/letter/d/f4b2a3/32.png) [@DanBlather](https://boards.straightdope.com/u/DanBlather)\ **Post date:** [September 18, 2006, 5:47pm UTC](https://boards.straightdope.com/t/why-are-there-two-difference-knitting-needle-measurements/373182/5 "2006-09-18T17:47:57Z")
There’s actually more than two. China uses a system based on (I think) old British sizes. US and mm sizes don’t match up that well either. Most needles these days are made in mm sizing and different mfgs use slightly different schemes to map US to mm. I used to have a spreadsheet with all this, but I can’t find it. If you are making a sweater, socks, or other garment where exact size matters you should always knit a sample (using the same needles you will be using for the finished project) and check the gauge. You may have to go up or down a needle size. Dan, who knows way more about needles than anyone should have to.