View Full Version : Caliber Conversion Chart

April 12, 2012, 07:16 PM
Title pretty well sums it up really. Does anyone know where I can find a chart that will tell what a caliber translates in the metric system?

A few I know for sure are that a 9mm = .36 and a .50 = 12.7mm

April 12, 2012, 07:19 PM
1 inch = 25.4 mm. The rest is just math. What are you looking for? Any inch to mm table will do what you want.


James K
April 12, 2012, 07:26 PM
If all you want is to "translate" a bullet diameter from one system to the other, there are on-line conversion sites that will do the job for you. But all they will do is tell you that ".38 inch" translates to 9.66 mm. They won't tell you that a .38 Special bullet is really .357" or that .38 Special is not the same as .38 S&W. Or they will tell you that 9mm is .354", but not that 9mm Largo isn't the same as 9mm Steyr, but is the same as 9mm Bergman-Bayard.

If you want to find out what a U.S. cartridge is called in Europe or vice versa (like 7.62x63 is .30-'06) then you need a book like Cartridges of the World.


April 14, 2012, 01:28 AM
Here is a good place to start:


April 14, 2012, 08:04 AM
all the metric data you ever need (http://members.shaw.ca/cstein0/metric.htm)

April 14, 2012, 08:52 AM
Interestingly enough, that chart lists the .303 Savage as having a .311 diameter bullet.:confused:

April 14, 2012, 11:25 AM
That's because .311 is SAAMI spec; 308 is just what everyone uses, according to Barnes's Cartridges of the World.

April 14, 2012, 12:56 PM
I had thought that with the .308, the lands of the rifling were .308, while the bullet was actually .311; I could be mistaken.

April 14, 2012, 01:35 PM
No, in a 308 Win, the lands are .300, the bullet .308 (which is why for a .303 a .311 bullet diameter is reasonable).