Arrow Spine Chart

An arrow must bend the right amount as it leaves the bow — too stiff or too weak and it flies off line and groups poorly. Spine charts from arrow makers are the place to start, but they all rest on the same few ideas: draw weight, arrow length and point weight. This guide explains those ideas with approximate starting points, and describes a pack of printable arrow build and tuning sheets.

What spine means

Static spine is a measure of how much a shaft bends under a standard load. In the common ATA (formerly AMO) method, a 1.94 lb (880 g) weight is hung from the middle of a shaft supported at points 28 inches apart; the deflection in inches, times 1,000, is the spine number. A 400-spine shaft bends 0.400 inches; a 300 is stiffer (bends less), a 500 weaker. Wooden arrows are traditionally rated in pounds of draw weight instead (for example 45–50 lb), using a different test.

Approximate starting points

These are broad, general starting points with 100-grain points, not any manufacturer’s chart. Every arrow maker publishes its own chart for its shafts, and they differ — use the chart for the shaft you are buying. Recurve and longbow shooters use the draw weight at their own draw length (“on the fingers”), which is often different from the weight marked on the limbs at 28 inches.

What makes an arrow act weaker or stiffer

Because length and point weight change how a shaft behaves, two archers with the same draw weight can need different spines. When in doubt between two sizes, many archers choose the stiffer one for compound bows and fine-tune with point weight.

Arrow weight, FOC and energy

GPI is the shaft’s grains per inch, printed on the box. Many target archers use an FOC of about 7–15%; some hunters prefer higher. Always check your local hunting regulations for minimum arrow weight or kinetic energy.

Worked example

An archer shoots a 60 lb compound bow with a 28-inch arrow and a 100-grain point. The table suggests a spine around 350–400. They choose a 350 shaft of 9.5 GPI: 28 × 9.5 = 266 grains, plus 100 point, 15 insert, 10 nock and 18 grains of vanes, gives 409 grains. The balance point is 16.2 inches from the nock throat, so FOC = (16.2 − 14) ÷ 28 × 100 ≈ 7.9%. At 270 fps, kinetic energy is 409 × 270² ÷ 450,240 ≈ 66 ft-lb.

Checking your spine by tuning

• Paper tuning: shoot through paper from a few feet away and read the tear. Tears that point left or right can indicate spine or rest issues.
• Bare-shaft tuning: compare where un-fletched and fletched arrows hit at 15–20 yards; a consistent offset suggests a spine mismatch.
• Walk-back tuning: helps with rest position and centre shot.
• Adjust point weight or draw weight a little to change dynamic spine before buying new shafts.
• Record every change in a tuning log so you can undo it.

Safety

Never dry-fire a bow, and never shoot an arrow that is too weak for the bow — an under-spined carbon arrow can break on release and injure the shooter. Flex each carbon arrow and check for cracks before shooting. Ask an archery shop to check your set-up if you are unsure.

What’s in the pack

• Arrow spine selection worksheet (draw weight, length, point weight, recommended range)
• Excel arrow build calculator: total weight, FOC, kinetic energy and momentum
• Printable arrow build sheet for recording components
• Paper and bare-shaft tuning log
• Blank chart template to copy the manufacturer chart for your shafts

All sheets print on US Letter and A4; the calculator opens in Excel and Google Sheets.

AI-assisted content

This guide was drafted with AI assistance and reviewed by Kedop. Spine figures are general starting points — always use the arrow manufacturer’s chart and a qualified pro shop for final selection.