# Is a 3/4 wrench and 19mm interchangeable? ? **URL:** \ **Category:** Factual Questions\ **Created:** [January 28, 2014, 8:58am UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935 "2014-01-28T08:58:23Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [January 29, 2014, 2:07pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/21 "2014-01-29T14:07:25Z")
> [@Jamicat](#): > > No one uses 19 mm. 😛 Many lug nuts / lug bolts are 19mm ---
**Author:** ![JerrySTL](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@JerrySTL](https://boards.straightdope.com/u/JerrySTL)\ **Post date:** [January 29, 2014, 2:27pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/22 "2014-01-29T14:27:36Z")
> [@Rick](#): > > Many lug nuts / lug bolts are 19mm Many spark plugs also. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [January 29, 2014, 2:54pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/23 "2014-01-29T14:54:28Z")
> [@Jamicat](#): > > No one uses 19 mm. I’ll put in another vote for “it’s actually rather common”. The rare sizes IME are 18mm and 16mm - but even these show up occasionally. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [January 29, 2014, 3:51pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/24 "2014-01-29T15:51:50Z")
> [@Jamicat](#): > > No one uses 19 mm. 😛 > [@48Willys](#): > > Bolding mine. NO ONE? VW does…Porsche does as well. > [@Rick](#): > > Many lug nuts / lug bolts are 19mm Methinks that the “:P” in **Jamicat’s** post was meant to be a smiley, and he was joking. 19mm bolt heads are quite common in Asian and European cars, and somewhat common in American cars. > [@JerrySTL](#): > > Many spark plugs also [are 19mm]. In lawnmowers, yes. Not in automobiles. Spark plug hexes are 5/8" or (in older vehicles) 13/16". > [@Xema](#): > > The rare sizes IME are 18mm and 16mm - but even these show up occasionally. 18mm bolt heads are rare in European cars, and I don’t recall seeing one in an Asian car, but they’re common in American cars. I agree that 16mm is rare. ---
**Author:** ![Jamicat](https://avatars.discourse-cdn.com/v4/letter/j/c67d28/32.png) [@Jamicat](https://boards.straightdope.com/u/Jamicat)\ **Post date:** [March 15, 2014, 6:15am UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/25 "2014-03-15T06:15:30Z")
> [@Gary\_T](#): > > Methinks that the “:P” in **Jamicat’s** **post was meant to be a smiley, and he was joking.** 19mm bolt heads are quite common in Asian and European cars, and somewhat common in American cars. > > In lawnmowers, yes. Not in automobiles. Spark plug hexes are 5/8" or (in older vehicles) 13/16". > > 18mm bolt heads are rare in European cars, and I don’t recall seeing one in an Asian car, but they’re common in American cars. I agree that 16mm is rare. I just figured they were 3/4 and went with that. 😉 No wonder my 19mm wrenches and sockets are so new looking. :smack: ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [March 16, 2014, 5:11am UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/26 "2014-03-16T05:11:47Z")
> [@Gary\_T](#): > > Methinks that the “:P” in **Jamicat’s** post was meant to be a smiley, and he was joking. 19mm bolt heads are quite common in Asian and European cars, and somewhat common in American cars. For future reference, the smiley on this board uses lowercase which makes the tongue come out the middle, like so: [noparse]:p[/noparse]. Uppercase makes it look like it’s coming out the side of the mouth: 😛 ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [March 16, 2014, 2:27pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/27 "2014-03-16T14:27:37Z")
The bolts holding the brake drums on a '78 VW Bus are the only time I’ve used 11 mm ::sticks tongue out:: If you’re not worried about putting it back together, use a cold chisel and big fucking hammer. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [March 17, 2014, 6:10pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/28 "2014-03-17T18:10:35Z")
> [@bibliophage](#): > > You got me curious, so I wrote a little Python script to check all sizes in millimeters… In my head I now hear this being read by John Cleese in a sarcastic tone, much like the “Cheese Shop” sketch. Oh yeah! BMW has 19mm all over the place and Fiat uses 13mm, which was once described to me as, “European Half-Inch”. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 17, 2014, 6:48pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/29 "2014-03-17T18:48:50Z")
> [@bigt](#): > > for future reference, the smiley on this board uses lowercase which makes the tongue come out the middle, like so: [noparse]:p[/noparse]. Uppercase makes it look like it’s coming out the side of the mouth: 😛 Þ, Þ, Þ, Þ, Þ, _snerk_ ---
**Author:** ![wolfman](https://avatars.discourse-cdn.com/v4/letter/w/a8b319/32.png) [@wolfman](https://boards.straightdope.com/u/wolfman)\ **Post date:** [March 17, 2014, 8:54pm UTC](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935/30 "2014-03-17T20:54:42Z")
> [@Gatopescado](#): > > Fiat uses 13mm, which was once described to me as, “European Half-Inch”. Hehe, the great moment of decision of personal lazyness vs “craftsmans integrity”; when you are all set to turn a 1/2 inch bolt and realize you grabbed the 13mm socket. It probably won’t strip it too much 😉 [Previous page](https://boards.straightdope.com/t/is-a-3-4-wrench-and-19mm-interchangeable/679935.md?page=1)