Arrow Spine Chart: Spine by Draw Weight and Length
Arrow spine is chosen from draw weight, arrow length and point weight together. With a 100 grain point, a compound at 60 lb and a 28 inch arrow needs about 400 spine, 70 lb needs about 340, and 50 lb needs about 500. Every extra 2 inches of arrow length or 25 grains of point weight moves you roughly one group stiffer or weaker.
Spine is the single most consequential number in arrow building, and the one most often chosen by guesswork. The chart below gives static spine by draw weight and arrow length for both compound and recurve setups, based on a 100 grain point. Read it as a starting shaft, then confirm with a bare shaft or paper test before you commit to a dozen.
Arrow spine chart by draw weight and arrow length
Values assume a 100 grain point and carbon shafts. Arrow length is measured carbon to carbon, from the throat of the nock to the end of the shaft, not including the point. Compound figures use peak draw weight with a release aid. Recurve figures use the weight you actually hold at your draw length, shot off the fingers.
| Draw weight | Compound 26 in | Compound 28 in | Compound 30 in | Compound 32 in | Recurve 28 in | Recurve 30 in |
|---|---|---|---|---|---|---|
| 20 lb | 1600-1900 | 1400-1600 | 1300 | n/a | 1600-1900 | 1400-1600 |
| 25 lb | 1300-1600 | 1200-1300 | 1000 | 900 | 1300-1600 | 1200-1300 |
| 30 lb | 1000-1300 | 900-1000 | 800-900 | 700-800 | 1000-1300 | 900-1000 |
| 35 lb | 900 | 800 | 700 | 600 | 900-1000 | 800 |
| 40 lb | 700-800 | 600-700 | 500-600 | 500 | 700-800 | 600-700 |
| 45 lb | 600-700 | 500-600 | 500 | 400-500 | 600 | 500-600 |
| 50 lb | 600 | 500 | 400-500 | 400 | 500-600 | 500 |
| 55 lb | 500-600 | 400-500 | 400 | 340-400 | 500 | 400-500 |
| 60 lb | 500 | 400 | 340-400 | 340 | 400-500 | 400 |
| 65 lb | 400-500 | 340-400 | 340 | 300-340 | 400 | 340-400 |
| 70 lb | 400 | 340 | 300-340 | 300 | 340-400 | 340 |
| 75 lb | 340-400 | 300-340 | 300 | 250-300 | 340 | 300-340 |
| 80 lb | 340 | 300 | 250-300 | 250 | 300-340 | 300 |
| 85 lb | n/a | 300 | 250-300 | 250 | 300 | 250-300 |
| 90 lb | n/a | 250-300 | 250 | 200-250 | 250-300 | 250 |
Manufacturers publish slightly different charts because their shafts differ in wall thickness, material and taper. Where two groups are shown, either will usually tune, and the stiffer of the two is the safer choice if you plan to add point weight later. Cells marked n/a are combinations almost nobody shoots.
What the spine number actually measures
Static spine is a deflection test, standardised by ASTM and used by every carbon shaft manufacturer. The shaft is supported on two points 28 inches apart and a 1.94 lb weight is hung from the centre. The amount the shaft sags, in thousandths of an inch, is the spine number.
So a 400 spine shaft deflects 0.400 inches under that load, and a 340 deflects 0.340 inches. Because a stiffer shaft sags less, lower numbers are stiffer. That inversion is the single most common point of confusion in arrow building, and it is worth saying out loud every time: 300 is stiffer than 500.
| Spine | Deflection | Relative stiffness | Typical use |
|---|---|---|---|
| 250 | 0.250 in | Very stiff | Heavy draw weights, long arrows, heavy points |
| 300 | 0.300 in | Stiff | 70 to 80 lb compounds, high point weight builds |
| 340 | 0.340 in | Stiff | The most common hunting spine, 65 to 75 lb |
| 400 | 0.400 in | Medium | 55 to 65 lb compounds, mid draw lengths |
| 500 | 0.500 in | Medium soft | 45 to 55 lb compounds, many target setups |
| 600 | 0.600 in | Soft | 40 to 45 lb, youth and lighter recurve |
| 700 to 900 | 0.700 to 0.900 in | Very soft | 30 to 40 lb bows, beginner recurve |
| 1000 and up | 1.000 in and up | Extremely soft | Youth bows and very light training weights |
Adjusting the chart for your actual build
The chart above assumes one specific arrow. Every deviation from that arrow shifts dynamic spine, which is how the shaft behaves once the string pushes it. Static spine is a property of the shaft. Dynamic spine is a property of the whole system, and it is the one that determines whether your broadheads fly with your field points.
| Change | Effect on dynamic spine | Roughly equivalent to |
|---|---|---|
| Add 25 grains of point weight | Acts weaker | +3 to 5 lb draw weight |
| Remove 25 grains of point weight | Acts stiffer | -3 to 5 lb draw weight |
| Add 1 inch of arrow length | Acts weaker | +4 to 6 lb draw weight |
| Cut 1 inch off the arrow | Acts stiffer | -4 to 6 lb draw weight |
| Swap an aluminium insert for brass | Acts weaker | Same as adding point weight |
| Fit a heavier outsert or hit collar | Acts weaker | +1 to 3 lb draw weight |
| Aggressive cam or short brace height | Acts weaker | +3 to 5 lb draw weight |
| Shoot fingers instead of a release | Needs a weaker shaft | About one spine group |
| Heavier nock or lighted nock | Acts slightly stiffer | Usually under one group |
These are approximations and manufacturers word them differently, but the directions are not in dispute. More weight up front and more length both weaken dynamic spine. Weight at the back and a shorter shaft both stiffen it. If you are building a heavy front-of-centre hunting arrow, plan for that before you buy: a 300 spine shaft with a 175 grain head often tunes where a 340 with a 100 grain head did.
How to use the chart without getting burned
Work in this order. First establish your real draw length, because a chart answer built on a guessed draw length is worthless. Our draw length calculator and the draw length chart both use the wingspan method. Then pick your arrow length, which is usually draw length plus 1 to 2 inches for a compound with a drop-away rest, more for a recurve shot off a shelf.
Next decide point weight, because that decision drives spine as hard as draw weight does. A hunter committed to a 150 grain broadhead is on a different row than a hunter shooting 100 grains at the same poundage. Only then read the chart. If you land between two groups, choose the stiffer one when your point weight might rise later, and the weaker one if you are near the short end of the arrow length range.
Finally, verify. Cross-check the shaft against your intended manufacturer's own chart, then prove it with a bare shaft or paper test. A shaft that reads correctly on a chart and tears consistently in paper is telling you something the chart cannot see, usually cam timing, rest position or nock fit.
Why compound and recurve need separate columns
A compound holds only 15 to 35 percent of peak weight at full draw, but the cam dumps that stored energy into the arrow very quickly, and a release aid puts the force almost perfectly in line with the shaft. The arrow flexes mainly in the vertical plane and recovers fast.
A recurve has no let-off, so the weight in your fingers at full draw is the weight doing the work, and that number rises about 2 to 3 lb for every inch you draw past the bow's marked length. Fingers also roll the string sideways on release, which sets up the horizontal bending known as archer's paradox. The shaft has to flex around the riser and recover in time to leave cleanly. That is why traditional archers tune spine by shooting rather than by chart, and why a recurve marked 50 lb rarely wants the same shaft as a compound marked 50 lb.
The safety floor that overrides everything
Whatever spine you land on, the finished arrow must weigh at least 5 grains per pound of draw weight. A 70 lb bow needs a 350 grain arrow minimum, a 60 lb bow needs 300 grains. Shooting lighter than that leaves energy in the limbs instead of the arrow, risks damaging the bow, and voids essentially every warranty on the market. Very light, very stiff shafts at high poundage are the usual way archers stumble into this, so check the finished weight with our total arrow weight calculator before you order.
Have setup and cutting work checked by a qualified pro shop, particularly the first time. A mis-cut shaft is a wasted arrow, but a mis-tuned broadhead is a wasted season.
Related tools and charts
- Arrow spine calculator: the same logic, applied to your exact numbers rather than a grid
- Total arrow weight calculator: confirm the 5 grain per pound floor
- Arrow FOC calculator: point weight drives spine and FOC at the same time
- Arrow weight chart: grains per inch by spine and diameter
- Arrow diameter chart: shaft outside diameter by spine and maker
Frequently asked questions
What spine arrow do I need for a 70 lb bow?
For a compound at 70 lb peak with a 28 inch arrow and a 100 grain point, 340 spine is the usual starting point. Cut the same arrow to 30 inches and you move to 300 or 340, because a longer shaft acts weaker. Go up to a 125 or 150 grain point and you shift weaker again. Spine is a system answer, not a draw weight answer, so change one variable at a time.
Is a lower spine number stiffer or weaker?
Lower is stiffer. The spine number is a deflection measurement in thousandths of an inch, taken by hanging a 1.94 lb weight from the centre of a shaft supported 28 inches apart. A 300 spine shaft sags 0.300 inches under that load and a 500 spine shaft sags 0.500 inches, so the 300 is the stiffer shaft. This trips up almost everyone once.
What happens if my arrow spine is wrong?
Too weak and the arrow over-flexes off the string, which shows up as erratic broadhead flight, tail-left tears in paper for a right-handed shooter, and groups that open up past 30 yards. Too stiff and the arrow does not recover cleanly either, giving tail-right tears and the same loss of accuracy. Field points hide both problems, which is why the mismatch usually appears the first time broadheads go on.
Does point weight change arrow spine?
It changes dynamic spine, which is the only spine that matters in flight. Static spine is a fixed property of the shaft, but adding mass at the front makes the shaft behave weaker because there is more inertia resisting the push of the string. As a rule of thumb, every 25 grains added up front acts roughly like adding 3 to 5 lb of draw weight, so a 50 grain jump can move you a whole spine group.
Do recurve and compound bows use the same spine chart?
No, and mixing them up is a common cause of bad flight. Compound charts are built around peak draw weight, a release aid, and a cam that accelerates the arrow hard. Recurve charts are built around the weight you are actually holding at your draw length, off the fingers, with the arrow bending around the riser. A recurve usually needs a slightly weaker shaft than a compound marked at the same poundage.
How accurate are static spine charts?
They get you to the right group most of the time and to within one group nearly always. They cannot account for cam aggression, string material, nock fit, centre shot, or your release, all of which shift dynamic spine. Treat the chart as the shaft you buy to start tuning, not the end of the process. Bare shaft or paper tuning is what confirms the choice.
How we choose: we compare published manufacturer specifications, verified owner reviews, and pro shop guidance. We do not test gear in person. Draw weight and arrow spine affect safety, so follow your bow manufacturer's specifications and have setup work checked by a qualified pro shop.