Do Lighted Nocks Affect Accuracy? FOC, Speed and Broadhead Impact, Modeled

Yes, a little, and mostly in a way you can predict. A 25-grain lighted nock weighs 16 grains more than a 9-grain standard nock, and all of it sits at the very back of the arrow. I ran that swap through the site's FOC and speed engines on 27 hunting builds, plus a drag-free drop check.

It costs about 1.9 to 2.8 points of FOC (under 2 on arrows over about 500 grains) and about 1.4–2% of launch speed, roughly 5 fps on a 400-grain arrow at 280 fps. With pins set for standard nocks, the arrow lands under 0.8 in lower at 20–30 yards and about 1.1 to 1.4 in lower at 40. All modeled and drag-free; drag changes it by only a few percent. So sight in and tune with the lighted nocks installed. If broadheads go wild while field points don't, check nock fit before you blame the weight.

The question isn't new. There's an ArcheryTalk thread asking it word for word that has passed 18,000 views since 2022, plus threads on making practice nocks weigh the same as lighted ones and on broadhead impacts getting a little erratic with lighted nocks. What none of them had was numbers for a specific build, so I ran them.

How Much Heavier Is a Lighted Nock Than a Standard One?

About 11 to 16 grains for the models whose makers publish a weight. A standard Easton 5mm X nock is 9 grains; the lighted nocks in our nock chart's sourced weight table run from about 20 grains to about 25. I modeled two cases: a 25-grain lighted nock (+16 gr) and a lighter 18-grain one (+9 gr). The engine also places a lighted nock's mass a bit deeper in the shaft (0.55 in ahead of the throat instead of 0.20 in), because the battery and LED sit up inside the shaft.

Weight at the tail works on a long lever. FOC is measured from the nock throat, so grains at the very back pull the balance point rearward harder than the same grains anywhere else on the shaft. On the 383-grain build below, the balance point slides back about two-thirds of an inch.

How Much FOC Does a Lighted Nock Take Off Your Arrow?

The 25-grain nock cost about 1.9 to 2.8 points of FOC across the grid; the 18-grain nock cost 1.1 to 1.6. The table is a cross-section of the 27 builds: 6.5, 8.5 and 10.5 grains per inch, 100 to 150-grain broadheads, 12 to 50-grain inserts, 28 in shaft, three 8-grain vanes.

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Modeled with the site's FOC engine (AMO definition, measured from the nock throat). 28 in shaft, three 8 gr vanes, broadhead. All 27 builds, plus a 27–30 in length check, are in the lighted-nock FOC grid (CSV).

Why Does the Same Nock Cost Less FOC on a Heavy Arrow?

Because 16 grains is a smaller share of a heavy arrow. Front weight helps only through the grains it adds: at the same total weight, a more front-heavy arrow loses slightly more (a 415-grain build at 21% FOC loses 2.5 points, a 408-grain build at 14% loses 2.3). The lightest build in the grid (327 gr, 100-grain head, 12-grain insert) loses 2.8 points; the heaviest (527 gr, 150-grain head, 50-grain insert) loses 1.9. Arrow length barely matters: on the 8.5 gpi build with a 125-grain head and a 30-grain insert, a 27 in shaft loses 2.3 points and a 30 in shaft 2.2, since the longer shaft adds weight of its own.

If you'd rather run your own build than read mine, the FOC and balance point optimizer has a lighted-nock what-if button, and the nock chart has a small lighted-nock FOC and speed calculator with the same engine behind it (it assumes a field point, so FOC reads about 0.1 point lower).

Will a Lighted Nock Make My Arrow Hit Low?

Yes, if your pins were set with standard nocks, and the miss grows fast with distance. A heavier arrow leaves the bow a little slower, so it spends longer in the air and drops further. Drop grows with the square of flight time, which means doubling the distance roughly quadruples the shift: on the 383-grain arrow it's 0.34 in at 20 yards, 1.37 in at 40 and 3.09 in at 60.

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How much lower the lighted-nock arrow lands than the standard-nock arrow, same pin, same aim. Modeled, drag-free; speed from the site's shared speed model.

About drag: these numbers leave it out on purpose. A lighted nock changes the arrow's mass, not its shape, so the air pushes on both arrows about the same. When I checked the shift with drag scaled to each arrow's mass, the answer moved by only a few percent, and if anything slightly down.

How Much Speed Does the Extra Weight Cost?

Not much, and it's the same percentage whatever your bow shoots. I ran it through the site's shared speed model, the same one behind the arrow weight vs speed comparison.

Modeled, relative to the launch speed of the standard-nock arrow (virtual-mass model, 30 gr). The percentage doesn't depend on bow speed.

The old shop rule of a fixed number of fps per grain misses here because it ignores how heavy the arrow already is. Sixteen grains is a bigger change on a 350-grain arrow than on a 550.

Should I Move My Sight Pins?

Only the long ones, and only after you've shot the lighted-nock arrows at that distance. One sight check at your longest shot covers 20–30 yd; from 40 out, check every pin with the arrows you'll hunt with. The trajectory and sight-pin visualizer shows where your pins sit for a given arrow weight and speed.

Can I Add Point Weight to Win the FOC Back, and What Does That Cost?

You can, but it takes more grains than the nock added, and it makes the drop problem bigger. To bring FOC back to the standard-nock value, the builds in my grid needed 22 to 36 grains more up front. Add that to the nock's 16 and the arrow loses 3.8 to 5.4% of its speed against the original standard-nock arrow.

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Modeled. Speed and drop are against the standard-nock arrow at 280 fps, pin set for that arrow; drop is drag-free.

On the 383-grain arrow, the lighted nock alone puts you 1.37 in low at 40 yards. Win the FOC back with 23 grains up front and that becomes 3.36 in at 40 and 7.56 in at 60. Heads and inserts come in 25-grain steps, so in practice this means one step heavier on the head, re-sighting every pin, and re-checking spine, since a heavier front makes the shaft act weaker (the dynamic spine calculator shows by how much).

My take: don't buy the FOC back by reflex. If your arrow is still inside your FOC target after the nock goes on, leave the front alone and move the long pins. Add front weight only when the lighted nock pushed you below the FOC you want for your broadhead. Whether that FOC is worth its trajectory cost is the subject of how much FOC adds to penetration.

Why Do My Broadheads Fly Differently With Lighted Nocks When Field Points Don't?

Weight alone rarely does it. A heavier nock moves every arrow the same way, so it shifts the whole group a little low. Erratic broadheads point at something that differs from arrow to arrow, or at a tune that only just held. In rough order of how big a change each can make:

1. String fit. A lighted nock has its own groove and throat, and their sizes aren't published, so a lighted nock may not fit your serving the way your standard nock did. Too tight or too loose changes how each arrow leaves the string, and broadheads show it first. A nock that isn't fully seated, or sits slightly crooked in the shaft, does the same thing to one arrow at a time.
2. A borderline tune. A fixed-blade head steers the arrow from the front, so any leftover launch error grows downrange in a way a field point hides. If the tune was only just good enough with standard nocks, a small change at the back can tip it over. The broadhead flight and stability checker shows how much margin your setup has.
3. Weight and flex. The modeled changes are small and the same for every arrow: about 2 points of FOC, about 2% of speed, and in my flex model a 25-grain lighted nock lowers the shaft's first bending frequency by about 4% (2.3–2.4% for an 18-grain nock). Whether that changes your broadhead flight depends on your tune, so check it on paper. I don't turn it into a spine number; the spine engine has no term for tail weight.

How Do I Tune With Lighted Nocks Installed?

Do it in this order, with the lighted nocks in every arrow you'll hunt with:

1. Hang-and-tap fit test. Snap each lighted-nock arrow onto your string and let it hang. It should stay on, then drop free with a light tap on the string. Anything that falls off on its own or needs a hard knock gets a different nock size before you shoot it.
2. Paper or bareshaft check. Shoot paper at 6–8 ft with field points, or bareshaft against fletched shafts, all with lighted nocks installed. My paper tuning guide and the bare shaft tune assistant cover the reading.
3. Broadheads vs field points at your longest shot. Three field points and three broadheads at the same aiming spot, at the longest distance you'll take a shot. Measure center to center.
4. Confirm or move the long pins. Shoot each pin past 30 yards with the hunting arrows. Move only the pins that need it.

Do Weight-Matched Practice Nocks Work?

For balance, yes. The gap to close is 16 grains for a 25-grain lighted nock, or 9 grains for an 18. I checked whether a standard nock weighted up to 25 grains balances the same as a 25-grain lighted nock whose mass sits a bit deeper in the shaft. It does: on three builds from 343 to 543 grains, the two came within 0.06 to 0.09 points of FOC. The weight matters, not where inside the nock it sits. Ballast pushed further into the shaft would move FOC slightly forward, about 0.14 points for 16 grains moved one inch on a 400-grain, 28 in arrow.

What a weighted practice nock can't copy is the lighted nock's groove. So practice with matched weights if you like, but do the fit test and the final broadhead check with the real lighted nocks.

1-Minute Decision Table: What Should You Do About Your Lighted Nocks?

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Frequently Asked Questions