Typical F.O.C.

Ranges FITA (Olymic-Style) 11-16%

3-D Archary 6-12% -

Field Archary 10-15% 

Hunting 10-15%

F.O.C. (Front-of-Center)

The term F.O.C. (Front-of-Center) describes the percentage of the arrow’s total weight that is located in the front half

of the arrow. The more weight that is located in the front half of the arrow, the more forward is the center-of-balance

of the arrow. Why is this important? It is generally believed that the F.O.C. balance position of the arrow is one of the

more important elements affecting the shape of the arrow’s trajectory curve.

Unfortunately, there are too many variables affecting the path of an arrow to make it possible to precalculate the

trajectory of an arrow simply by controlling its F.O.C.. Some archers, though, find it valuable to determine and

record the F.O.C. of their arrows once they have achieved the flight characteristics they desire.

Changes in the trajectory of an arrow, for whatever reason, are quite apparent in archery events or bowhunting

conditions that call for shots to be made at both short and long ranges. Bows for these situations usually include the

use of multiple sight pins or multiple premarked sight settings. Since changing the F.O.C. of an arrow may

change the shape of its trajectory, it may also change the

preset sight locations on the bow sight.

F.O.C. Guidelines

The balance of an arrow can be modified by adding weight

to either the front or the rear of the shaft. Heavier vanes,

for example, increase the weight of the rear portion of the

AMO-Standard F.O.C. balance formula

100 x (A-L/2)

L

F.O.C. % =

L = Correct Arrow Length—Distance from bottom of nock groove to end of shaft

A = Distance from bottom of nock groove to finished arrow balance position (includes

weight of point [+ insert], nock system and fletching)

A 1/2 Length = L/2

Front-of-Center balance position of the finished arrow

Center of Correct Arrow Length

F.O.C.

Distance

L = Correct Arrow Length

Determining F.O.C.%

arrow. Replacing vanes with feathers lightens the rear of the arrow. Various points, inserts, and even added weights

are used to modify the weight of the front of the arrow. Because of the differences in archers and types of shooting

there is not a perfect F.O.C. for each setup. To provide a good starting point when constructing a set of arrows or

when analyzing an arrow’s flight characteristics, it may be helpful to look at the range of F.O.C.s most common for

each style of archery.

Typical F.O.C. Ranges

FITA (Olympic-Style) 11-16 %

3-D Archery 6-12 %

Field Archery 10-15 %

Hunting 10-15 %

Use the following formula to calculate the exact F.O.C. of

an arrow.

FOC Calculator

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