The Complete Arrow Building System (2026)

Most arrow guides start at the wrong end. They open with a shaft — some 4mm hunting flavor of the year — and work backward from there. That's how you end up with a beautiful arrow that tails left at forty and a drawer full of components you paid for and can't use.

An arrow isn't a shaft. It's a system. Six or seven parts that either agree with each other and your bow, or don't. Get the order right and the whole thing falls together in an afternoon. Get it wrong and you'll spend a season blaming your form for a spine problem.

This is the order I build in, and the order the numbers want. Draw weight and the animal decide the arrow. The arrow decides the components. The components you can shop last, once you know what has to be true. If you'd rather watch the numbers move while you read this, open the free arrow builder in another tab and build along — every number below is one it calculates for you.

Start With the Two Numbers That Decide Everything

Before you touch a shaft, you need two things pinned down: what your bow throws, and what you're going to kill with it.

Your bow throws a draw weight and a draw length. Those two numbers, plus your point weight and arrow length, set your spine — the stiffness the arrow has to be to leave your bow straight. Everybody knows draw weight. Fewer people respect draw length, and almost nobody accounts for the point up front, which is exactly why so many "chart-correct" arrows fly like garbage. More on that in the spine section.

The animal sets the other half: total weight and FOC. A whitetail at twenty yards does not need the same arrow as an elk quartering away at fifty, and neither of them needs the 700-grain EFOC missile the internet will try to sell you. Decide the game first. It tells you the weight window and the FOC target, and those two constrain every component choice after.

Write both down. Draw weight, draw length. Target animal, weight range, FOC target. That's the spec sheet. Everything else is filling it in.

Spine: The One You Have to Get Right

You can be sloppy about a lot of things in an arrow build. Spine is not one of them. A weak arrow off a hard cam doesn't just group poorly — it leaves the bow with energy going sideways, and your broadhead will amplify every bit of it downrange.

Here's the part the chart won't tell you: spine isn't static. The number printed on the shaft is static spine, measured by hanging a weight off a supported shaft in a lab. What your arrow actually does when the string slams it forward is dynamic spine, and that depends on point weight, arrow length, cam aggression, and release style. Two archers at 70 pounds and 29 inches can need different spines. I've seen it on the bench more times than I can count.

Start with the chart as a ballpark. For a 28-inch arrow, 100-grain point, modern compound:

• 40–50 lb draw: 500 spine
• 50–60 lb: 400 spine
• 60–70 lb: 340 spine
• 70–80 lb: 300 spine
• 80+ lb or a heavy point: 250 spine

Now adjust, because the ballpark is where most people stop and it's why their arrows don't fly. Go stiffer — a lower spine number — when your arrow is longer than 28 inches (roughly one spine class per inch over), when your point is heavier than 100 grains, or when you shoot an aggressive cam or a hard-punch thumb release. Go weaker for the opposite.

Point weight is the one that wrecks people. The trend toward 175- and 200-grain heads has broken the chart for half the hunting world. Every 25 grains you add up front weakens your dynamic spine by about a class — it's roughly equivalent to adding an inch of arrow length. A 70-pound shooter running 200 up front on a chart-correct 340 is actually shooting a class light, and wonders all season why the broadheads tail left. Get this one wrong and nothing downstream saves you.

Cam matters too, and most posts get which cams are aggressive exactly backward. A Hoyt RX-9 or RX-10 is a smooth cam — drawn-out wall, forgiving back end. Same with a Mathews on the smoother side of the lineup. The ones that punish a weak spine are the speed bows: a PSE Sicario or Omen will find a soft arrow instantly. Smooth cam, you get more forgiveness with a weaker spine. Aggressive cam, build stiffer than the chart says.

While we're here — let-off. My rule is 70 to 75 percent, whatever puts me around 20–21 pounds of holding weight. Elite and a few others will sell you 90. I'd never recommend it and I don't want anyone above 80. Less holding weight means less back tension, and hand torque and grip slop start driving your pin float. Target shooters live at 65–75 for a reason. Ninety is past the middle ground, not ahead of it.

If reading all that made your eyes cross, that's the point of the tool. Drop your draw weight, draw length, arrow length, point and insert weight, and shaft into the free spine calculator and it applies every one of those adjustments for you, then flags when you're sitting on the edge of two classes and should test both. It runs the same physics I just walked through — it just does the arithmetic without the headache. For the deeper reads, see how to read a spine chart and when to ignore it and why spine runs on IBO, not your chronograph.

FOC: A Tool, Not a Religion

FOC — front-of-center — is how far your arrow's balance point sits ahead of the shaft's physical center, as a percentage of total arrow length. A perfectly balanced arrow is 0 percent. A normal hunting arrow runs 10–15. High FOC starts around 15; EFOC is 19 and up. The marketing wants you to believe more is always better. It isn't.

What FOC buys you is stability. A forward center of mass pulls the back of the arrow into line, the same reason a dart has a heavy nose and light tail. That stability shows up in two real places — crosswind resistance, and broadhead correction, where the blade acts like a sail up front and the forward weight fights it. Both real, both bounded.

What it doesn't buy you is dramatic penetration. Penetration is total weight and momentum, plus a small assist from a skinnier shaft diameter. FOC adds a little bit on marginal hits by keeping the arrow true through bone, but it's a single-digit improvement above 15 percent, not the 30 percent the loudest voices claim. The reproducible field data just doesn't support the hype, and I've written up what the Ashby-style penetration claims actually show when you run real arrows through real animals.

And FOC costs you speed. To raise it you add weight up front without much in back, and that weight slows the arrow. Roughly 50 grains up front to go from 12 to 17 percent costs you about 10 fps — enough to shift your sight tape a few yards at sixty. On a deer, nothing. On an elk at distance, that's a sight-tape difference. You also weaken dynamic spine doing it, which loops you right back to the section above.

So the honest targets: 7–12 percent for target and 3D, 10–15 for whitetail (and 15 is plenty for whitetail — more is wasted speed for the animal), 12–18 for elk and moose, 15–20 for African plains game and bear where the penetration math earns its keep. For ninety percent of bowhunters the answer is a 29-inch arrow, a 50-grain insert, a 125-grain point on a 340 shaft, landing around 12–15 percent. It kills anything in North America and flies straight in wind.

The FOC calculator built into the arrow builder does the measurement for you as you swap parts — you don't need to balance the finished arrow on a knife edge and do the fraction by hand, though the old-school method still works if you like it.

Total Weight and Momentum — the Penetration Half

Spine gets the arrow there straight. Weight and momentum are what put it through. This is where the "light and fast versus heavy and slow" argument lives, and both camps are half right.

Kinetic energy is what the marketing prints. Momentum — mass times velocity — is what actually predicts penetration, because a heavier arrow holds its energy through resistance instead of dumping it on impact. That's why a 500-grain arrow at 270 fps out-penetrates a 400-grain arrow at 300 on heavy bone, even though the KE numbers look close. It's also why "as light as possible for a flat trajectory" is a target-archery answer that gets people in trouble on elk.

For most hunting, land somewhere sensible: 6.5 to 8 grains per pound of draw weight for whitetail, 8-plus for elk and bigger. A 70-pound bow wants a finished arrow somewhere around 450–500 grains for deer, more for elk. You don't need to chase 650 unless you're going after the biggest, toughest animals on earth. Build the weight into total mass and a reasonable FOC, not into a 300-grain broadhead that wrecks your spine.

The builder returns total weight, KE, and speed the moment you change a component, so you can see the tradeoff instead of guessing at it. Build a light one and a heavy one side by side and look at what each costs you.

The Components, Front to Back

Now — and only now — you shop. You know your spine, your weight window, and your FOC target. The parts either serve those numbers or they don't.

Shaft. This is the arrow. Everything else hangs off it. For most hunters a mid-diameter carbon in the right spine from a maker with honest tolerances does the job — Easton Axis and FMJ are the reference standard, Gold Tip runs a touch stiff for the printed number, and if you want to go small, micro-diameter shafts like the Altra Centrum or a 4mm Easton buy you real wind resistance and penetration — the case for switching to 4mm is strong for anyone who hunts open country. Match Grade shafts tighten the spine and straightness tolerance if you want the arrows to actually match each other, which matters more than most people admit — your quiver full of "identical" arrows isn't.

Insert and collar. This is your front-weight lever and it changes spine, so treat it like a spine part, not an afterthought. A heavier insert or an impact collar pushes FOC up without touching point weight, and the length of a footing or collar stiffens the arrow by shortening the flexing section. Know the difference between a half-out, an outsert, and a HIT insert before you buy, and don't assume brass inserts are a free FOC shortcut — see the insert breakdown for what actually holds up. Shop inserts, collars, and components here.

Point. Field points to practice, broadheads to hunt, and they should weigh the same and fly the same — if they don't, that's a tune problem, not a point problem. Match your head to your game with the elk or whitetail broadhead guides; browse heads here. Point weight is also your cheapest FOC and spine adjustment, so decide it inside the build, not after.

Wrap and vanes. Rear-end parts, and they matter more than their weight suggests. A wrap is the cheapest tuning aid you're not using, and vane length is a tradeoff most hunters get wrong — enough steering to control your broadhead, not so much you're dragging speed and inviting wind. Feathers versus plastic is a real decision, not a preference. Rear weight also stiffens dynamic spine slightly, which is one more reason to build the whole arrow at once instead of in pieces.

Nock. The cheap part that ends the arrow. A lighted nock adds rear weight (stiffening spine a hair) and, if you hunt low light, earns its cost in recovered arrows and confirmed hits — just buy one that actually works rather than a scam. Firenock is the most engineered system out there.

Notice how many of those parts touched spine. That's the whole argument for building the arrow as a system in one tool instead of stacking guesses.

Cut Length — Don't Let the Shop Talk You Short

One field decision that costs people accuracy: arrow length. Shops love to cut arrows short for a little speed and a lot of "it looks tuned." Cut your arrows longer than the shop wants to. A slightly longer arrow is more forgiving of spine, gives you room to tune, and costs you almost nothing in the real world. You can always trim. You can't un-cut.

Cost — Spend on Tolerance, Skip the Marketing

You do not need $60-a-shaft arrows to kill a deer. A well-built mid-tier arrow, spined right and tuned, beats a premium arrow built wrong every day of the week. You can build a hunting arrow for under $100 a half-dozen that outperforms most of what walks out of a pro shop pre-fletched.

Spend where it matters: honest spine and straightness tolerance in the shaft, a broadhead that flies with your field points, an insert that fits. Save on the stuff that's marketing — you don't need the fancy nock, the exotic wrap, or the heaviest brass collar in the catalog. Match Grade shafts are worth it if you compete or shoot long; for a treestand at twenty, standard tolerance and a good tune will bury a broadhead every time.

The Build Order, Start to Finish

Put it all together and the process is short:

1. Write your spec — draw weight and length, target animal, weight and FOC window.
2. Set spine from the chart, then adjust for point weight, length, cam, and release. Don't skip the adjustments.
3. Pick components that serve the spine, weight, and FOC you decided — shaft, insert, point, wrap, vanes, nock.
4. Build three or four, not one. Arrows vary.
5. Bareshaft tune at twenty. Build per the numbers, pull the fletching off one, and watch where it lands against a fletched arrow. Bareshaft left of fletched for a right-handed shooter reads weak; right reads stiff. The chart got you eighty percent there; bareshafts get you the rest. Bareshaft tuning is also where building hands off to tuning — spine is the first thing to rule out when you tune the bow.

Steps 1 through 3 are exactly what the calculator does in about ninety seconds. Steps 4 and 5 happen at the bench — no software builds the arrow for you; that part's on you and your hands.

Build It Before You Buy It — the Tool

Everything above is why the free arrow builder exists. You drop in your bow, draw, shaft, insert, point, and nock, and it returns dynamic spine, FOC, total weight, KE, and speed — live, as you change parts. No chart worship, no three tabs open, no spreadsheet. You can build the light setup and the heavy setup side by side and see exactly what each one costs you before a single component leaves the shelf.

It's free, and there's no login to run it. Make a free account and your builds save so you can come back to the ones that worked — free, no card. When you outgrow building single arrows and start living on the bench — tuning the whole rig, printing sight tapes, keeping a saved library of builds you can compare over time, and a full tuning history — that's the membership, at $8/month or $72/year. The first 100 Founding Flock members lock it at $36/year for life (annual-only). But you can build every arrow in this guide without paying a cent, and most people should start there.

FAQ

What spine do I need for a 70-pound bow?
Start at 340 for a 28-inch arrow with a 100–125 grain point, then adjust. Heavy point up front (150+ grains), a longer arrow, or an aggressive speed cam all push you stiffer — often to a 300 or 250. Run your exact numbers through the spine calculator rather than trusting the flat chart.

What FOC should I shoot for hunting?
10–15 percent for whitetail, 12–18 for elk and moose, 15–20 for the biggest, toughest game. Above 15 percent you're trading real speed for a single-digit penetration gain — worth it on an elk shoulder, wasted on a broadside deer.

Is a heavier arrow always better for penetration?
Heavier holds its momentum through bone, which is why hunting arrows lean heavy. But past a sensible weight for your animal you're just giving up trajectory. Around 6.5–8 grains per pound for deer, 8-plus for elk, is the honest window.

Do I really need a micro-diameter (4mm) shaft?
If you hunt open country or shoot past forty, the wind resistance and penetration are a real advantage. For a pure treestand hunter inside twenty-five yards, a well-tuned 5mm is plenty. It's an honest tradeoff, not a mandate.

How much does a good hunting arrow cost to build?
Under $100 for a half-dozen if you build smart. Spend on shaft tolerance and a broadhead that flies true; skip the marketing parts.