FOC Reference Chart: Front of Centre Bands Explained
Front of centre under about 12 percent is normal, 12 to 19 percent is high, 19 to 30 percent is extreme, and above 30 percent is ultra extreme. Most target arrows sit between 7 and 12 percent and most hunting guidance recommends 10 to 15 percent, with larger game builds commonly running 15 to 20 percent.
Front of centre describes where the weight of an arrow sits, not how much of it there is. Two arrows of identical weight can behave very differently depending on whether that weight is concentrated at the point or spread down the shaft. This chart gives the standard bands, what each one is used for, and exactly what each component change does to the number.
FOC percentage bands
| FOC band | Classification | Typical use | Trajectory | Notes |
|---|---|---|---|---|
| Under 2% | Very low | Indoor fat shafts, some novelty builds | Flattest | Steers poorly with anything but a field point |
| 2 to 5% | Low | Indoor target at short distance | Very flat | Acceptable only where wind and distance do not matter |
| 5 to 7% | Low normal | Some target and field builds | Very flat | Below most manufacturer recommendations |
| 7 to 9% | Normal | Target and field archery, common factory target arrows | Flat | Bottom of the widely recommended target range |
| 9 to 10% | Normal | General purpose, 3D competition | Flat | A sensible all-round figure |
| 10 to 11% | Normal | Entry point of the hunting recommendation | Flat | Where a 100 grain head on a light shaft often lands |
| 11 to 12% | Normal | Typical factory hunting arrow | Flat | The most common real-world figure |
| 12 to 13% | High | Deer sized game, fixed broadheads | Slightly steeper | Start of what penetration research calls high FOC |
| 13 to 14% | High | Hunting, mid weight builds | Slightly steeper | Comfortable middle of the hunting band |
| 14 to 15% | High | Hunting, heavier point weights | Steeper | Top of the commonly recommended hunting range |
| 15 to 16% | High | Elk, bear and hog builds | Steeper | Usually reached with a brass insert or 150 grain head |
| 16 to 17% | High | Large game builds | Steeper | Fletching becomes more important for stability |
| 17 to 19% | High, upper | Heavy hunting arrows, single bevel heads | Noticeably steeper | Approaching the extreme classification |
| 19 to 22% | Extreme (EFOC) | Large game, deliberate heavy builds | Steep | Requires careful tuning and usually a stiffer shaft |
| 22 to 25% | Extreme | Heavy plains game and specialist builds | Steep | Sight marks change substantially past 30 yards |
| 25 to 30% | Extreme, upper | Specialist heavy arrow builds | Very steep | Component selection becomes limiting |
| Over 30% | Ultra extreme (UEFOC) | The largest and heaviest boned game | Very steep | Rare, and demands a purpose-built arrow |
The normal, high, extreme and ultra extreme labels come from long-running penetration research and are widely quoted in the archery literature. The boundaries are conventions rather than physical thresholds, and manufacturers publish slightly different recommended ranges.
The formula and how to measure it
FOC percentage equals the balance point minus half the arrow length, divided by the arrow length, multiplied by 100. Arrow length here is measured from the throat of the nock to the end of the shaft, not including the point, and the balance point is measured from the same starting reference.
To measure it, finish the arrow completely, including the broadhead you intend to hunt with, then balance it across a straight edge until it sits level. Mark that point, measure from the nock throat, and run the arithmetic. A 29 inch arrow balancing at 17.9 inches gives (17.9 - 14.5) / 29 x 100 = 11.7 percent. The FOC calculator does it for you and flags which band you have landed in.
Two measurement mistakes account for most disagreements about FOC. Including the point in the arrow length inflates the answer, and measuring from the back of the nock rather than the throat shifts everything by a quarter inch or so. Use the same convention every time and your figures will at least be comparable to each other.
What each change does to FOC
The table below uses one representative arrow throughout so the comparisons are real: a 29 inch shaft at 8.5 grains per inch, a 12 grain aluminium insert, a 10 grain nock and 18 grains of fletching, with a 100 grain point as the baseline.
| Change from baseline | Finished weight | FOC | Change | Cost |
|---|---|---|---|---|
| Baseline, 100 gr point | 387 gr | 11.8% | reference | None |
| 125 gr point | 412 gr | 14.2% | +2.4 | About 8 fps, acts a spine step weaker |
| 150 gr point | 437 gr | 16.4% | +4.6 | About 17 fps, acts 8 lb weaker in spine |
| 50 gr brass insert, 100 gr point | 425 gr | 15.1% | +3.3 | About 13 fps, keeps your tuned broadhead |
| 50 gr brass insert, 125 gr point | 450 gr | 17.1% | +5.3 | About 21 fps |
| 50 gr brass insert, 150 gr point | 475 gr | 19.0% | +7.2 | About 29 fps, needs a stiffer shaft |
| Feathers instead of vanes | 378 gr | 13.1% | +1.3 | Nothing in speed, less durable in rain |
| Two inch vanes instead of three | 381 gr | 12.6% | +0.9 | Less steering for fixed broadheads |
| Cut the arrow one inch shorter | 378 gr | 12.1% | +0.3 | Acts stiffer in spine, check broadhead clearance |
| Add a lighted nock | 399 gr | 9.9% | -1.9 | Moves the balance point backward |
Speed costs use the standard approximation of 1 fps per 3 grains. Your arrow will produce different absolute numbers, but the relative sizes of these levers hold: point weight is the largest, insert weight is second, and everything at the rear of the arrow is a small adjustment.
Reading the trade-off honestly
Every route to higher FOC except lightening the rear costs speed, and speed buys forgiveness on distance estimation. That is the real trade, and it is why the answer depends on how you hunt. A treestand hunter shooting inside 30 yards at deer gives up almost nothing by running 16 percent FOC and a 470 grain arrow, because the trajectory difference at that distance is small. A western hunter taking 50 and 60 yard shots pays for it in drop and in wind.
The lightening-the-rear route deserves more attention than it gets. Switching to feathers or low-profile vanes and dropping a lighted nock gets you 2 to 3 points of FOC for free, without a spine change and without slowing the arrow down. It will not take you from 11 percent to 20, but it is the cheapest FOC on the table.
What high FOC does not fix
FOC is not a substitute for tune. An arrow that leaves the bow with a tail-left tear will still leave with a tail-left tear when you add 50 grains to the point, and the heavier head will magnify the steering error rather than correct it. Work through the tuning troubleshooting chart first, then adjust balance.
It is also not a substitute for spine. Adding point weight weakens dynamic spine, which is why the high FOC builds in the table above eventually need a stiffer shaft. Going from a 100 to a 150 grain head acts roughly like adding 8 lb of draw weight. Check the arrow spine chart before you commit, or run the numbers through the spine calculator with your intended point weight entered.
Finally, FOC does not exempt an arrow from the safety floor. The finished arrow must still weigh at least 5 grains per pound of draw weight. High FOC builds almost always clear it easily, but a very light shaft with a heavy point and a short cut is worth checking with the total arrow weight calculator.
Choosing a target FOC
- Indoor target: 5 to 10 percent. Distance is fixed and short, so trajectory and line cutting matter more than steering.
- Outdoor target and field: 8 to 12 percent. Enough stability for wind, still flat enough for long distances.
- 3D competition: 9 to 12 percent. Distance estimation is the game, so flatter is better.
- Deer sized game: 10 to 15 percent. The mainstream recommendation for good reason.
- Elk, bear and hog: 14 to 19 percent. Bias toward penetration, usually with a heavier arrow overall.
- The largest game: 19 percent and up. Specialist territory, usually paired with a heavy single bevel head.
Related tools and charts
- Arrow FOC calculator: your balance point turned into a percentage
- Total arrow weight calculator: the weight half of the equation
- Broadhead weight chart: the largest single lever on FOC
- Arrow weight chart: component weights front and rear
- Kinetic energy calculator: momentum, the other penetration factor
Frequently asked questions
What is a good FOC percentage for hunting?
Ten to 15 percent is the range most commonly recommended for hunting arrows, and it is where a typical build with a 100 to 125 grain head naturally lands. Below 10 percent the arrow steers less confidently with a fixed broadhead. Above 15 percent you gain penetration bias at a growing cost in trajectory. Larger game builds often run 15 to 20 percent deliberately.
How do you calculate FOC?
Subtract half the arrow length from the balance point measured from the nock throat, divide by the arrow length, then multiply by 100. Arrow length for this purpose is measured from the throat of the nock to the end of the shaft, excluding the point. A 29 inch arrow balancing at 17.9 inches gives 11.8 percent FOC. Balance the finished arrow with the broadhead fitted.
Does higher FOC always improve penetration?
It helps, but the relationship is not unlimited. Concentrating mass at the front keeps the arrow driving forward when it meets resistance instead of yawing off line, which is why extreme FOC builds are popular for large animals. Past roughly 20 percent the trajectory penalty grows quickly and the arrow becomes very sensitive to fletching and tune. Momentum and broadhead design still do more of the work.
Does FOC affect trajectory?
Indirectly, and mostly through weight. Raising FOC almost always means adding grains up front, and the added mass slows the arrow, which steepens the drop. FOC itself has a modest effect on drag and stability. The practical rule is that every route to higher FOC costs some speed, so decide how much trajectory you are willing to trade before choosing a target percentage.
What is the difference between FOC and EFOC?
They are points on the same scale rather than different measurements. Figures under about 12 percent are usually called normal, 12 to 19 percent high, 19 to 30 percent extreme or EFOC, and above 30 percent ultra extreme. The classifications come from long-running penetration research and are widely cited, though the exact boundaries are conventions rather than physical thresholds.
How do I raise FOC without adding much weight?
Take weight off the back rather than adding it to the front. Switching from three-inch vanes to feathers, using low-profile two-inch vanes, dropping a wrap, or removing a heavy lighted nock all move the balance point forward while making the arrow lighter. The gains are smaller than a heavier point but they cost nothing in speed. Cutting the arrow shorter helps slightly too.
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.