Conversions for all Cartridges: Inches & MM
When it comes to converting calibers from inches to millimeters most people get lost in the sauce. We’re hoping to help change that. Below are some easy to read and understand charts that take all the guess work out on the conversion process. But first, let’s break down a few things.
The Main Issue
The majority of the confusion comes due to the two different systems used to measure the bore diameter of a cartridge, the measurement done in inches, and the exact same measurement taken in millimeters. It’s our hope that these bullet and cartridge charts will give you all the information you need to fully and quickly understand and identify the cartridge you need regardless of the measurement used.
Rifle Conversion Chart: Inch/mm
| Caliber Name | Diameter in MM | Diameter in Inch. |
|---|
| .50 | 12.95mm | .51" |
| .416 | 10.57mm | .416" |
| .375 | 9.53mm | .375" |
| .366 | 9.3mm | .366" |
| .33 | 8.59mm | .338" |
| .325 | 8.2mm | .323" |
| .30 | 7.82mm | .308" |
| .280 | 7.21mm | .284" |
| .270 | 7.04mm | .277" |
| .260 | 6.71mm | .264" |
| .257 | 6.53mm | .257" |
| .243 | 6.17mm | .243" |
| .22 (not lr) | 5.7mm | .224" |
| .22 (lr) | 5.66mm | .223" |
| .223 | 5.7mm | .224" |
| .204 | 5.2mm | .204" |
| .17 | 4.32mm | .172" |
Pistol Conversion Chart: Inch/mm
| Cartridge | Diameter in MM | Diameter in Inch. |
|---|
| .50AE | 12.7mm | .50" |
| .45ACP | 11.5mm | .452" |
| .44 Magnum | 10.9mm | .429" |
| .40S&W | 10mm | .40" |
| 9mm | 9.02mm | .355" |
| .38 Special | 9.10mm | .357" |
| .380ACP | 9mm | .355" |
| .357 Magnum | 9.10mm | .357" |
| .22LR | 5.66mm | .223" |
Full Conversion Chart: Inch/mm
| Cartridge Name | Diameter in MM | Diameter in Inch. |
|---|
| .50 BMG | 12.95mm | .51" |
| .458 Win Mag | 11.63mm | .458" |
| .45-70 Govt | 11.63mm | .458" |
| .450 Bushmaster | 11.48mm | .452" |
| .444 Marlin | 10.90mm | .429" |
| .416 Rigby | 10.57mm | .416" |
| .416 Remington Magnum | 10.57mm | .416" |
| .416 Ruger | 10.57mm | .416" |
| .378 Weather by Magnum | 9.53mm | .375" |
| .375 Ruger | 9.53mm | .375" |
| .375 H&H | 9.53mm | .375" |
| 9.3 x 62mm Mauser | 9.30mm | .366" |
| .35 Whelen | 9.09mm | .358" |
| .350 Legend | 9.07mm | .357" |
| .338 RUM | 8.59mm | .338" |
| .338-378 Weather by Mag | 8.59mm | .338" |
| .33 Nosler | 8.59mm | .338" |
| .340 Weather by Magnum | 8.59mm | .338" |
| .338 Federal | 8.59mm | .338" |
| .338 Lapua Magnum | 8.59mm | .338" |
| .338 Win Mag | 8.59mm | .338" |
| .325 WSM | 8.2mm | .323" |
| .30-378 Weather by Mag | 7.82mm | .308" |
| .300 Ruger (RCM) | 7.82mm | .308" |
| .30 Nosler | 7.82mm | .308" |
| 7.62 x 39mm | 7.82mm | .308" |
| .300 Blackout | 7.82mm | .308" |
| .30-30 Winchester | 7.82mm | .308" |
| .300 RUM | 7.82mm | .308" |
| .300 PRC | 7.82mm | .308" |
| .300 Weather by Magnum | 7.82mm | .308" |
| .300 WSM | 7.82mm | .308" |
| .30-06 Springfield | 7.82mm | .308" |
| .300 Winchester Magnum | 7.82mm | .308" |
| .308 Winchester | 7.82mm | .308" |
| 7 WSM | 7.21mm | .284" |
| 7mm Mauser | 7.21mm | .284" |
| 7 STW | 7.21mm | .284" |
| 7 SAUM | 7.21mm | .284" |
| 7mm Weather by Magnum | 7.21mm | .284" |
| .280 Remington | 7.21mm | .284" |
| .280 Ackley Improved | 7.21mm | .284" |
| .28 Nosler | 7.21mm | .284" |
| 7mm Rem Mag | 7.21mm | .284" |
| 7mm-08 Remington | 7.21mm | .284" |
| .27 Nosler | 7.04mm | .277" |
| 6.8 Remington SPC | 7.04mm | .277" |
| 6.8 Western | 7.04mm | .277" |
| .270 Weather by Magnum | 7.04mm | .277" |
| .270 WSM | 7.04mm | .277" |
| .270 Winchester | 7.04mm | .277" |
| 6.5 Grendel | 6.71mm | .264" |
| 6.5 Weather by RPM | 6.71mm | .264" |
| .264 Winchester Magnum | 6.71mm | .264" |
| 6.5 x 55 Swedish Mauser | 6.71mm | .264" |
| 6.5-284 Norma Match | 6.71mm | .264" |
| .26 Nosler | 6.71mm | .264" |
| 6.5-300 Weather by Mag | 6.71mm | .264" |
| .260 Remington | 6.71mm | .264" |
| 6.5 PRC | 6.71mm | .264" |
| 6.5 Creedmoor | 6.71mm | .264" |
| .257 Weather by Magnum | 6.53mm | .257" |
| .25-06 Remington | 6.53mm | .257" |
| 6mm Creedmoor | 6.17mm | .243" |
| 6mm Remington | 6.17mm | .243" |
| .240 Weather by Magnum | 6.17mm | .243" |
| 6mm BR | 6.17mm | .243" |
| .243 Winchester | 6.17mm | .243" |
| .222 Remington | 5.7mm | .224" |
| .22 Hornet | 5.7mm | .224" |
| .223 / 5.56 | 5.7mm | .224" |
| .22 WMR | 5.7mm | .224" |
| .22 Creedmoor | 5.7mm | .224" |
| .22 Nosler | 5.7mm | .224" |
| .22-250 | 5.7mm | .224" |
| .224 Valkyrie | 5.7mm | .224" |
| .220 Swift | 5.7mm | .224" |
| .22lr | 5.66mm | .223" |
| .204 Ruger | 5.2mm | .204" |
| .17 HMR | 4.32mm | .172" |
| .17 WSM | 4.32mm | .172" |
| .17 Hornet | 4.32mm | .172" |
