The arrow-length rule
The arrow-length rule: what it is and how it changes the arrow you should shoot.
Dry-fire warning
Crossbow bolt data and archery arrow spine, nock and thread data are quoted from each manufacturer's published figures, owner documentation and industry standards, cited on every page. A nock, spine or grain-weight mismatch can cause a dry-fire that damages the bow and can injure the shooter. Confirm against your own owner's manual and the arrow maker's own chart before shooting, and never drop below the stated minimum total weight.
| Draw length | Measured from the nock groove to the front of the bow handle at full draw |
|---|---|
| Arrow length | Cut about 1 to 2 inches longer than draw length so the broadhead clears the bow shelf |
| Effect on spine | A longer cut flexes more, so it needs a stiffer spine |
| Why it matters | Cutting too short risks drawing the broadhead onto the hand; leaving it long weakens dynamic spine |
Field notes
Draw length is measured at full draw from the deepest part of the nock groove to the front of the bow handle. Arrow length is not the same thing.
The rule is to cut the arrow about one to two inches longer than draw length, so a broadhead sits ahead of the shelf and the hand, never level with it.
Length feeds straight back into spine: every extra inch of shaft flexes more, so a longer arrow needs a stiffer spine to fly the same. Settle length first, then read the spine chart at that length.
Related rules and examples
Sources: 3Rivers Archery - How to find the right spine (spine selection charts) · Easton - Hunting Arrow Size Selection chart and adjustment rules (PN 301055-A)