F.O.C. Calculator
Please fill in the values below. We can then calculate the Front of Center value of your arrows.
Formula & reference values
F.O.C. % = 100 × ( B − A / 2 ) / A
- World Archery11–16 %
- Field10–15 %
- Bowhunting10–15 %
- 3D6–12 %
A higher value (balance point towards the point) makes the arrow fly more precisely, but also more nose-heavy. More important than an exact percentage is that every arrow in your set has the same F.O.C. value.
In a nutshell
- F.O.C. stands for Front of Center and shows how far an arrow's balance point sits ahead of its centre, expressed as a percentage.
- Formula F.O.C. percent equals 100 times (balance point minus half the arrow length) divided by arrow length, measured from the nock groove.
- Reference ranges are 11 to 16 percent for World Archery target, 10 to 15 percent for field and bowhunting, and 6 to 12 percent for 3D.
- Measuring needs two values, the arrow length from the nock groove to the shaft end and the distance from the nock groove to the balance point.
- A higher value shifts the balance forward, which stabilises the flight but costs range and makes the arrow more nose-heavy.
- Arrow set Consistency matters more than an exact number, so every arrow in a set should share the same F.O.C.
What is arrow F.O.C.?
F.O.C. stands for Front of Center and describes how far an arrow's balance point sits ahead of its geometric centre. The value is given as a percentage. An F.O.C. of 10 percent means the balance point is shifted forward by 10 percent of the arrow length, towards the point. If the balance point sits exactly in the middle, the F.O.C. is zero percent.
F.O.C. is driven mainly by the point weight and by inserts or outserts at the front end. The heavier the point relative to the rest of the arrow, the further the balance point moves forward and the higher the F.O.C. With the calculator above you get the value in seconds, without doing the maths yourself.
How do you calculate F.O.C.?
The formula for F.O.C. is F.O.C. percent equals 100 times (balance point minus half the arrow length) divided by arrow length. In short form that is 100 times (B minus A divided by 2) divided by A. Here A is the arrow length from the nock groove to the shaft end and B is the distance from the nock groove to the balance point.
An example. Your arrow is 32 inches long and balances at 18.4 inches from the nock groove. The centre sits at 16 inches, so the balance point is 2.4 inches ahead of the centre. Divided by the arrow length and multiplied by 100, that gives an F.O.C. of 7.5 percent. The unit does not matter, because inches or centimetres cancel out in the formula. You can measure in inches or in centimetres and the result stays the same.
How to measure arrow length and balance point
F.O.C. needs exactly two values. Measure the arrow length from the nock groove, the deepest point of the nock, to the end of the shaft. The point is not included here. Find the balance point by resting the fully built arrow, complete with point, nock and fletching, on a narrow edge or your finger until it sits level. The distance from that spot back to the nock groove is your value B.
It is important to measure the arrow exactly as you shoot it, with the point and fletching fitted. If you later change the point weight or the nock, the balance point shifts and so does the F.O.C. Moving from a 100 grain point to a 125 grain point pushes the balance point noticeably forward.
Which F.O.C. is right?
The right F.O.C. depends on your discipline. The values below are proven reference ranges and a solid starting point for tuning your arrows.
| Discipline | Recommended F.O.C. | Character |
|---|---|---|
| World Archery (target) | 11 to 16 percent | Stable flight over long distances |
| Field archery | 10 to 15 percent | Good balance of stability and speed |
| Bowhunting | 10 to 15 percent | High penetration and a steady flight |
| 3D | 6 to 12 percent | Flatter trajectory on estimated distances |
If you are just starting out, you do not need to lock in the second decimal place. A value within the target range of your discipline is perfectly enough to begin with. Only once you tune for consistent groups does fine adjustment through point weight become worthwhile.
What does a high or low F.O.C. do?
A higher F.O.C. shifts the balance point further forward. This makes the arrow steadier and more directionally stable in flight, because the weight up front leads like a dart. The trade-off is a more curved trajectory, since a nose-heavy arrow drops faster and loses height over distance. On long shots you need to allow for that when aiming.
A lower F.O.C. gives a flatter trajectory and more range, but reacts more sensitively to small release errors and to crosswind. This is why target archers run higher values over long distances, while 3D shooters often choose a slightly lower F.O.C. to shoot flatter on estimated ranges. How strongly the effect shows depends also on the shaft diameter and the total arrow weight.
Why every arrow should share the same F.O.C.
Consistency within your set matters more than an exact percentage. When every arrow has the same F.O.C., they fly identically and land in one group with clean technique. If the values scatter, for example because different point weights are fitted, you get deviations that have nothing to do with your technique and that are hard to pin down during tuning.
F.O.C. is therefore one building block in the interplay of spine, arrow length and point weight. If you want to build your arrows from scratch, our spine calculator helps alongside this tool to find the right shaft for your draw weight and draw length. Together, both values are the basis for an arrow that leaves the bow window cleanly and hits reliably.
FAQs
What does F.O.C. mean on an arrow?
F.O.C. stands for Front of Center and gives, as a percentage, how far an arrow's balance point sits ahead of its geometric centre. A value of 10 percent means the balance point is shifted forward by 10 percent of the arrow length towards the point. F.O.C. is driven mainly by the point weight.
How do you calculate the F.O.C. of an arrow?
The formula is F.O.C. percent equals 100 times (balance point minus half the arrow length) divided by arrow length. The arrow length is measured from the nock groove to the shaft end without the point, and the balance point is the distance from the nock groove to the spot where the arrow balances level. The unit does not matter, because it cancels out in the formula.
Which F.O.C. is right for which discipline?
As reference ranges, 11 to 16 percent suit World Archery target shooting, 10 to 15 percent suit field archery and bowhunting, and 6 to 12 percent suit 3D. More important than an exact value is that every arrow in a set shares the same F.O.C.
What does a high F.O.C. do?
A high F.O.C. shifts the balance point forward and makes the arrow flight steadier and more directionally stable. The downside is a more curved trajectory, as the nose-heavy arrow drops faster and loses height over distance. A lower F.O.C. flies flatter but reacts more sensitively to errors and crosswind.
How do you measure the balance point of an arrow?
Find the balance point by resting the fully built arrow, complete with point, nock and fletching, on a narrow edge or your finger until it sits level. The distance from that spot to the nock groove is the value B you enter into the calculator. Always measure the arrow exactly as you shoot it.