# What does GPI mean?



## jwilson48 (Apr 1, 2009)

grains per inch...just multiply number by length of arrow and you know how heavy it is.


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## Tn10point (Mar 5, 2005)

GPI = Grains Per Inch. More grains means the arrow weighs more.


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## deadx (Aug 6, 2002)

11.3 grains per inch. Higher or lower in gpi means slower or faster arrow speeds from the same bow. It also means stiffer or weaker spine.


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## DonsHarley (Sep 10, 2003)

deadx said:


> 11.3 grains per inch. Higher or lower in gpi means slower or faster arrow speeds from the same bow. It also means stiffer or weaker spine.


GPI has nothing to do with spine being weaker or stiffer. Example, Easton FMJ 340 has a GPI of 11.3 and a Easton Flatline 340 has a GPI of 8.2 .


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## MadBullArchery (Jan 25, 2008)

jwilson48 said:


> grains per inch...just multiply number by length of arrow and you know how heavy it is.


Yep! What he said. Has nothing to really do with spine. Just weight.


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## Elgavilan (Feb 7, 2010)

As a general rule, arrows of the same model, from the same manufacturer, such as Gold Tip, will have a higher GPI with the stiffer spine, and therefore they do weigh more as the spine goes up. That does not neccessarily apply when comparing arrows between different manufacturers or even different model arrows from the same manufaturer.

Mike


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## Bean Burrito (Apr 20, 2011)

Higher GPI arrows will weigh more at the same length. So more energy, less speed, but probably in the end more penetration. FMJ's are getting up there as far as weight goes.


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## r.petty.12532 (Feb 17, 2015)

Ok I shoot Easton flatliners 400 7.4 gpi What does the 7.4 gpi mean? Thanks


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## jwilson48 (Apr 1, 2009)

it means if you have a 30" arrow the carbon weighs 222 grains before insert, nock, vanes, glue, etc.


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## BuckshutrJR (Feb 21, 2011)

Elgavilan said:


> As a general rule, arrows of the same model, from the same manufacturer, such as Gold Tip, will have a higher GPI with the stiffer spine, and therefore they do weigh more as the spine goes up. That does not neccessarily apply when comparing arrows between different manufacturers or even different model arrows from the same manufaturer.
> 
> Mike


Very well put


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## bigrobc (Aug 10, 2011)

r.petty.12532 said:


> Ok I shoot Easton flatliners 400 7.4 gpi What does the 7.4 gpi mean? Thanks


It means the arrow weighs 7.4 grains per every inch


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## r.petty.12532 (Feb 17, 2015)

Ok thought so


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