You choose arrow spine from the manufacturer's selection chart for the shaft model you intend to buy, going in with two numbers: the draw weight you actually hold on your fingers at your draw length, and the length of the arrow. Where they meet, the chart gives a spine, or a group of spines to choose from, and that is the starting point; confirmation comes from shooting, because the same shaft behaves differently on different bows. Beginners need to know one more thing: in the first year draw weight usually goes up, and an arrow that suits today's bow can become too weak for next season's.
What happens to the arrow as it leaves the bow is covered in the article on the archer's paradox, and choosing arrows once you compete in choosing competition arrows; here I stay with the basics, without naming any brand.
What spine is
Spine is the stiffness of the shaft, how much it resists bending. The number printed on carbon and aluminium shafts is a static spine: the shaft rests on two supports 28 inches (711 mm) apart, a weight of 1.94 lb, about 880 g, hangs from the middle, and the sag is measured in thousandths of an inch. A shaft that bends half an inch is a 500 spine; one that bends 380 thousandths, or 9.65 mm, is a 380. The method was set out in an American standard, ASTM F2031, withdrawn in 2023 with no replacement, and the number is still read that way.
The direction of the number is the first thing that confuses beginners. Because the value is the deflection itself, the higher the number, the weaker the shaft: a 600 bends more than a 500, and a 500 more than a 400. Wooden arrows follow a different convention and are usually sold with spine given in pounds, so their chart is read with the seller's own guidance.
When the arrow is shot, though, the string drives the shaft from behind, compresses it and makes it flex as it accelerates: how it behaves under those conditions is called dynamic spine, and it also depends on the bow, the point, the length and the release. Models have said for twenty-five years that spine measured at rest is not enough to predict how the arrow behaves when shot, but no test shooting the same shafts has confirmed it, and in the registry the statement is transferred. In practice, shafts of different models with the same number should not be treated as equivalent, and when you change model you start again from its own chart.
What the choice depends on
The basic rule is that arrow spine has to be matched to draw weight and arrow length: a more powerful bow bends the shaft more and needs a stiffer arrow, and on the same bow a longer arrow behaves like a weaker one. The rule holds in every model since 1990, but nobody has yet compared how archers group with a suitable and with an unsuitable spine, and in the registry it is reported. For someone buying a first set of arrows, three factors matter.
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Actual draw weight, at your draw length
The figure marked on the limbs applies at the maker's reference draw length, usually 28 inches, and with a different draw length your actual draw weight changes. In 49 university beginners the women pulled 21.24 lb on average against the 26.18 marked. In the registry the statement that the draw weight marked on the bow differs from what the archer pulls at their draw length is contested, because a second study, with archers close to the reference draw length, found the figure almost exact. For the chart, then, what counts is the draw weight measured with a bow scale at your own draw length, and most clubs have one.
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Arrow length
It depends on your draw length and on the margin left in front of the rest, and you can estimate it with the draw and arrow length calculator. Each chart states where it measures length from and to, so check before cutting. In a model of a competition recurve, ten extra millimetres of shaft are worth about 4.5 newtons less draw weight, roughly one pound, and since a shaft can be shortened but never lengthened, when in doubt you start slightly long and cut after testing.
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Point weight
On the same shaft, a heavier point makes the arrow behave as weaker, and many charts state the point weight they are calculated for. The only model that has calculated the effect finds it small, half a newton of draw weight going from 120 to 100 grains against eleven for one spine size, and gives more weight to the tail: in the registry the statement on tail weight and arrow tuning is transferred. The point, then, is for fine adjustment, not for rescuing a spine that is well off.
The same models give an idea of how narrow the window is. In one of them, moving to the neighbouring spine calls for about 11 newtons of draw weight, two and a half pounds, while a recurve can only be adjusted within about 10% of its nominal weight: at a given draw length, only one or two spines can be tuned well. The compound bow is a separate case, because with a release aid the arrow flexes less sideways than with a finger release and manufacturers often give it a chart of its own; a single study, using a shooting machine, found that there arrows stiffer than recommended group as well as the recommended one, and it is reported.
How to read a selection chart
Charts vary from one manufacturer to another, but almost all of them work the same way: draw weight in one direction, arrow length in the other, and a spine indication where they meet. Some give the number, others a group that a key translates into spines. The diagram below shows the reading path, with letters in place of numbers because it is nobody's actual chart.
The first step is picking the right chart: the one for the shaft model you want to buy and for your type of bow, checking which point weight it is calculated for. Then you find the row for the draw weight measured at your draw length and the column for the arrow length, measured the way the chart measures it. Where they meet is the spine, or the group, and the key tells you which shafts it contains. If you land on the border between two cells, point weight and the cut of the shaft let you shift slightly one way or the other.
That the charts are where the best archers start is reported on the strength of a single observation, but a clear one: in high-speed video of sixteen recurve archers from national teams, arrow stiffness was in every case the one the charts give for their draw weight and length. The observation says that the best archers follow them, not that they point to the best shaft, and on that second question there is only a 2025 numerical model, not yet checked with shooting, which finds them too stiff, by up to four sizes, for long arrows and low draw weights. Low draw weights are exactly what beginners shoot, which is why the chart is best taken as a guide to be checked.
Why you check it on the range
The classic check is the bare shaft test: you shoot a few fletched arrows and a few unfletched shafts at the same distance and see where they land relative to each other. Without the fletching to straighten it in flight, the bare shaft shows the spine error the vanes would otherwise hide. For a right-handed archer shooting with the fingers, bare shafts landing to the left of the fletched group mean the arrow is too stiff, and to the right that it is too weak; for a left-handed archer the directions are reversed. It is the rule in tuning manuals, and the registry holds no study that has checked it with archers shooting; a shooting machine with a right-handed bow, however, sent the stiffer arrows from a batch of the same spine to the left, in the direction the rule predicts.
For beginners the test has a timing limit: in my experience the bare shaft says something only once the release is consistent enough to group, because while the fletched arrows are still scattered, the offset of the bare shaft is mixed up with the variation in the shot itself. The right moment usually comes after the first few months, at a short distance and with a coach beside you, once the nocking point has been set: the step-by-step procedure is in the article on arrow flight, and full tuning in the one on bow tuning. Corrections are made one at a time, with the point, the length or a few turns of the limb bolts, and you shoot again after each one.
When to buy arrows and when to check them again
During the beginners' course the club usually lends the arrows, and your own first set comes later, once your draw length is stable and you know which bow you want to carry on with. With a riser that takes interchangeable limbs, draw weight rises in steps during the first year, and since in the models one spine size is worth about two and a half pounds, a change of limbs by a few pounds can already move you into the next cell. That is why the first set is best chosen on the assumption that it will last a season, and why it makes sense to ask at the club whether anyone has used shafts in the spine you need.
Spine needs checking again whenever something in the system changes: the draw weight, the arrow length, the point weight or the shaft model. The rules, on the other hand, do not ask you for any particular spine. In World Archery target competitions the shaft may not exceed 9.3 mm in diameter and the point 9.4 mm, every arrow carries the archer's name or initials, and the arrows shot in an end must be identical in appearance. In Italy FITARCO and FIARC, and internationally IFAA, each have their own rulebook, published on their website or available from your club.