Arrow Trajectory & Sight-Pin Visualizer

A bow stores energy like a spring, and how much it stores comes down to two things: how hard it is to pull, and how far it travels while pulling. Draw weight covers the first, and the second is your draw length minus the brace height the string starts at.

None of that reaches the arrow intact. A recurve or longbow hands over roughly two-thirds to three-quarters of it; the rest goes into limb movement, string mass, hand shock and noise. The tool sits near the top of that band, which suits a modern limb on a stiff riser. Whatever energy does arrive gets shared out by arrow weight — a heavier shaft leaves slower off the same bow, always.

Check it: 45 lb at 28 in with a 420 gr arrow comes out at 195 fps here. Chronograph numbers for that kind of setup usually land in the 180–200 fps band. If yours reads low, your limbs are giving up more than the model assumes — a heavy selfbow often does.

Advertised IBO is a lab figure taken at one fixed setup: 70 lb, a 30 in draw and a 350 gr arrow. Almost nobody shoots that, so the number on the box has to be walked back to your bow.

Each step away from the test setup moves speed by an amount that has held up well against chronograph data: pulling less weight costs a little, a shorter draw costs noticeably more per inch because the string spends less time pushing, and every extra grain of arrow trades speed for weight. The tool applies all three and shows the result.

Check it: a 330 IBO bow at 70 lb, 29 in draw and a 420 gr arrow reads 294 fps. Real bows often land a few fps under that, because IBO comes from ideal conditions and because a peep, string silencers and a heavy nock each take a little back. If your chronograph says 288, treat this as an optimistic ceiling — nudge the arrow weight slider until the readout matches and everything downstream corrects with it.

An arrow is slowing down the whole way to the target, and two things set how fast: how much surface is hanging in the air, and how cleanly the front end cuts through it. Both get treated as a steady bleed of speed per unit of distance, so a longer shot loses proportionally more.

Sail area gets counted separately, because drag and wind sensitivity aren't the same thing. Low-profile target vanes sit at the bottom of both scales. Hunting vanes with a bit of helical are the middle of the road. Four vanes or a full helical clamp cost more. Long feathers cost the most — they steer beautifully and they catch the most air. Up front, a field point is the clean baseline, a mechanical adds a little, and a fixed blade adds the most, which is why fixed-blade shooters feel crosswind first.

These are the softest numbers in the whole tool. They're set so the drift output matches what shooters consistently report rather than measured in a wind tunnel, and they can't know your vane height, shaft diameter or how much helical you actually clamped in. Treat the ranking as solid and the exact figures as approximate.

Gravity doesn't care about distance, only time. It pulls at the same rate for every arrow ever shot, so the only question is how long it gets. That's why drop grows out of all proportion to range: the arrow is also slowing down as it goes, so the far half of a long shot takes longer than the near half, and gravity is working the entire while.

Roughly, doubling the distance quadruples the drop — and a bit more once drag is counted. That's the whole reason the last ten yards of a bad range estimate hurt far more than the first ten.

Check it: a 294 fps compound covers 40 yd in about 0.44 s and falls roughly 37 in below its launch line. A 195 fps recurve takes 0.65 s over the same distance and drops well over twice as far — same gravity, more time.

Gravity works straight down, no matter which way you're pointing. So on a steep shot from a stand or up a hillside, it only gets to act across the flat part of the distance — the horizontal leg under the line of sight. The side view beside the angle slider draws both legs so you can see the gap open up as you tilt.

That's what the plays like readout is telling you, and it's the same logic an angle-compensating rangefinder uses. Up and down behave identically here. Flight time and wind drift still use the true line-of-sight distance, because the arrow really does fly that far.

Check it: 40 yd at 30° down plays like about 35 yd. Under roughly 15° the difference is small enough to ignore; past 30° it will cost you an arrow if you don't account for it.

Aiming down the shaft, your eye sits above the arrow, so the point already appears low on the target before gravity does anything at all. Two things set how low: how far your eye is above the arrow at anchor, and how far away the target is relative to the length of the arrow you're looking along.

Close in, that eye-above-arrow offset dominates and the point looks well below the spot — the familiar gap. Push the distance out and the offset stops mattering while drop keeps growing, until the two cancel exactly. That distance is your point-on, and past it you're holding above the spot instead of below it.

Check it: 45 lb, 28 in, 420 gr with a corner-of-mouth anchor gives a point-on near 48 yd, and trad shooters running that kind of setup commonly report point-on in the 45–55 yd band. Drop to a low under-chin anchor and point-on runs far past 70 yd — which is exactly why Olympic recurve shooters need a sight. Try the Olympic preset and watch what the hold does.

A sighted-in pin does one thing: it puts your eye on a straight line that crosses the arrow's arc at exactly one distance. At that distance you hold dead on. Anywhere past it the arrow has fallen away from the line, and the amount it has fallen away is your hold-over.

It isn't simply the total drop, because the pin was already aimed slightly high to reach its own distance. The tool subtracts that built-in allowance, which is why a 20 yd pin asks for far less hold-over at 40 yd than the raw drop figure would suggest.

Check it: a 20 yd pin on a 294 fps bow asks for roughly 20 in of hold-over at 40 yd. Sight tapes and shop charts for that speed land in the 16–20 in range.

Here's the part most people get backwards: a crosswind doesn't push the arrow for the whole flight. An arrow with no drag at all would reach the target and land where it was aimed, wind or no wind. Drift only exists because drag holds the arrow back, and the wind gets exactly that lost time to work with. Shooters and long-range rifle folk both call it lag time.

So the drift you see comes from three things: how much time drag cost you, how hard the wind is blowing sideways, and how much sail area your fletching and head are carrying. A quartering wind counts for a bit over two-thirds of a full crosswind — only the sideways part of it moves anything.

Check it: 294 fps, 10 mph full crosswind, standard hunting vanes and a field point gives about 1 in at 20 yd, 4.5 in at 40 yd and 10 in at 60 yd. Swap to a fixed-blade head and 40 yd becomes closer to 6.5 in; go to 5 in feathers and it's over 8 in. Those are the numbers bowhunters and 3D shooters describe when wind comes up.

Straight on is the neutral position on the dial, and it reads zero drift by design. A pure head or tailwind isn't truly zero — it changes the arrow's airspeed, so it nudges drop a little — but that effect is small next to the sideways push a crosswind gives you, and sideways is what moves an arrow off a vital circle. Treat this setting as "no crosswind" rather than as a wind you've modelled.

Both figures are worked out at impact, not at the string, because that's the only place they matter. Drag has been eating speed the whole way, so a 40 yd number is meaningfully lower than the launch figure — and it drops off further the more sail area you're carrying.

The two tell you different things. Kinetic energy leans hard on speed, so a light fast arrow flatters it. Momentum weights mass and speed evenly, which is why heavy-arrow shooters quote it — it tracks the ability to keep driving through hide, bone and muscle rather than the ability to arrive quickly. When the two disagree about which of your builds is "better," momentum is usually the one bowhunters trust for penetration.

The Enough for readout maps impact KE onto the bands the hunting community works with: roughly 25 ft·lb and up for turkey and small game, 42 and up for deer-class animals, 65 and up for elk and larger. Those are widely used rules of thumb, not law, and they assume a tuned arrow flying straight with a sharp head. A well-placed 45 ft·lb arrow out-performs a badly placed 70 ft·lb one every single time.

Check it: 420 gr at 294 fps launch reads about 81 ft·lb and 0.55 slug·ft/s at the string, and noticeably less by 40 yd. Compare that against any published arrow-energy chart for your speed and weight.

Baked-in assumptions:

• The arrow leaves flying straight. An untuned arrow bleeds speed and lands somewhere this model never predicted.
• Sea-level air at moderate temperature. Thin mountain air stretches point-on; cold dense air shortens it.
• A modern, reasonably efficient recurve limb — and advertised IBO taken at face value for compounds.
• Your eye sits about an arrow's length behind the point, which is close for most anchors.
• Steady wind, the same at the target as where you're standing.
• A 122 cm FITA face, or a broadside deer with a ~10 in vital circle. Both drawings are to scale with the numbers beside them.

Not modelled at all: gusts and terrain-broken wind, broadhead planing on an untuned arrow, cam lean or timing, string and rest contact, arrow spine, release consistency, or your own form under pressure. Any one of those moves impact further than an error in these estimates.

• Speed: chronograph three arrows and average. If you're 10 fps off, nudge the arrow weight slider until the readout matches — everything downstream corrects with it.
• Point-on, trad: walk back until the point sits on the spot and you're still hitting. That distance is your real point-on.
• Hold-over, compound: aim dead on with your 20 yd pin at 40 yd and measure how far low the group lands.
• Wind: shoot a group in a steady crosswind with a flag out, then shoot the same group with the wind at your back.

If your results sit outside the ranges here, your setup is telling you something the arithmetic can't — and that's worth more than any estimate. Share your link in the comments below and say what your bow actually did.