Arrow shafts are rated for mass "by the inch."  So a rating of 8.2 means that the arrow shaft weighs 8.2 grains per every inch of arrow shaft.  Do not confuse grains with grams.  It's always grains!  If your arrow shaft weighs 8.2 gpi and the shaft is say 29" long, then the shaft portion of your arrow will weigh 237.8 grains (8.2 x 29).  But keep in mind that does not include the nock, insert, tip, fletchings, or glue.  So your finished arrow will always be considerably heavier than the shaft alone.  Also, be advised that these gpi ratings surely include some rounding and margin of error.  Don't be alarmed if your scale shows a few grains more or less than the mathematical estimate.     

SAFETY REMINDER:  Light arrows fly fast and flat, but don't go for too much of a good thing.  A modern compound bow must shoot AT LEAST 5 grains of arrow mass per pound of bow draw weight.  So if you are shooting a bow with a 65 lb. draw weight, your finished arrow must weigh at least 325 grains (65 x 5).  Older bows and traditional bows should shoot even more arrow mass (at least 7 grains/lb) for best margins of safety.  We know you love speed ... but shooting underweight arrows is dangerous and puts considerable stress on your bow and its components.  Always follow minimum arrow mass recommendations for your type of bow. 

Finally, there is considerable debate in our industry regarding the use of light arrows for bowhunting.  Some people claim that since lighter arrows fly faster, they arrive on target more quickly - with better accuracy - resulting in fewer wounds and misses.  But others claim that heavier arrows offer better penetration - resulting in more ethical bow kills.  Whatever your side of this debate, you can generally think of arrows weighing less than 10 gpi as being arrows designed for speed, and arrows with a gpi over 10 as being designed for penetration.  Interestingly enough, the most popular hunting arrows are in the 8.0-10.0 gpi range.  If you need help, call our pro-shop at 877-410-7811 or email us for assistance.

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