Arrow Spine Chart Guide: How to Choose the Right Hunting Carbon Arrows

Spine is how much a carbon shaft bends when you shoot it. TitleX rates that as 250, 300, 350, and 400. A lower number is stiffer. GPI (grains per inch) is how heavy the shaft is, and it changes with both model and spine. Use this chart to pick a starting spine, then confirm flight with field points and the broadhead you hunt with.

TitleX GPI by model and spine

These values match the published TitleX shaft pages and the 3D custom arrow builder. They are shaft mass only — inserts, points, nocks, vanes, and wraps add more.

TX-5 is the heaviest 5mm hunting shaft in this set. Mach XV is the lighter 5mm option at the same spine. TX-23 is the lightest GPI of the three. Same spine number does not mean the same finished arrow.

How to choose arrow spine

You choose spine from the bow you hunt with, not from a brand name. Draw weight at your draw length, cut length, and point weight set how much the carbon has to bend. Then pick the TitleX row.

1. Start from your bow’s draw weight at your draw length, not the limb stamp alone.
2. Decide cut length. Longer shafts act weaker in flight even when the printed spine stays the same.
3. Lock point and insert weight. Adding front weight also makes the shaft act weaker.
4. Pick the TitleX model for diameter and GPI, then the spine row that matches that build.
5. Bare-shaft or paper-tune with the same point weight you will hunt, then broadhead-tune.

TitleX publishes four spines. Start on this chart, then confirm with field points and the broadhead you hunt with. If you already shoot a known carbon hunting spine from another brand, match stiffness first, then compare GPI so FOC and total weight do not surprise you.

How to choose arrow length

Cut length is measured on the shaft, not including the point. A practical start is draw length plus the extra you need for rest clearance and the broadhead you hunt with. Extra length adds mass and weakens dynamic spine. Cutting shorter stiffens the reaction and usually raises FOC if you keep the same front weight. Set length in the 3D custom arrow builder so the FOC estimate updates with the cut.

FOC after you pick a spine

Front of center (FOC) is how far the balance point sits ahead of the shaft midpoint, as a percent of length. Inserts and point weight raise FOC. Wraps, vanes, and lighted nocks add rear mass and lower it. The builder shows estimated total weight and FOC for TX-5, TX-23, and Mach XV as you change those parts. Use that number to compare builds; confirm the finished arrow on a scale and a balance check before a hunt.

When this chart is not enough

• You are between spines after a large point-weight or length change — tune, do not assume the next row is automatic.
• You are switching from a much lighter or heavier GPI shaft at the same spine number.
• Fixed-blade broadheads planed in practice — helical, rest, and FOC matter as much as the chart row.

Related resources: how to measure draw length, FOC calculator, 3D custom arrow builder, arrow wrap installation, TX-5 arrow review, best arrows for elk hunting.