Point Weight for Target FOC Calculator
Already know your current FOC and want more? Enter your current build and target FOC to see exactly how many grains of point, insert, or broadhead weight to add, plus the new total arrow weight.
🎯 Point Weight for Target FOC Calculator
Enter your values below. Results update as you type.
Balance point B = L × (0.5 + FOC ÷ 100)
Weight to add = W × (B_target − B_current) ÷ (L − B_target)
Added weight is treated as sitting at the end of the shaft. A point's center of mass sits slightly ahead of that, so real-world results need a few grains less.
📊 Weight Needed per FOC Step
Grains to add at the front for a 28 in shaft, starting from 10% FOC.
| Current Arrow | To 12% FOC | To 15% FOC | To 18% FOC | To 20% FOC |
|---|---|---|---|---|
| 350 gr | +18 gr | +50 gr | +87 gr | +117 gr |
| 420 gr | +22 gr | +60 gr | +105 gr | +140 gr |
| 480 gr | +25 gr | +69 gr | +120 gr | +160 gr |
📘 Worked Example
A 28 in shaft at 420 grains with 10% FOC balances 16.8 in from the nock throat. To reach 15% FOC the balance point must move to 18.2 in. The weight needed is 420 × (18.2 − 16.8) ÷ (28 − 18.2) = 60 grains.
Swapping a 100-grain head for a 160-grain head, or adding a 50-grain brass insert plus a 10-grain heavier point, gets you there. The arrow ends up at about 480 grains.
Watch your spine
Adding front weight makes the arrow act weaker. A jump of 50 grains or more up front can push a shaft out of its spine range. Re-check with the arrow spine calculator after any big change, and see the high FOC heavy arrow calculator for complete builds.
❓ Frequently Asked Questions
How much point weight do I need to increase FOC?
On a typical 28 in, 420-grain arrow, each extra 1% FOC takes roughly 10–14 grains up front. The exact number depends on shaft length and total weight.
Is it better to add weight to the point or the insert?
Both raise FOC the same way since they sit at the front. Heavier inserts keep your broadhead choice open; heavier points are simpler to swap.
Why does adding front weight weaken spine?
More mass at the tip resists acceleration, so the shaft bends more on launch. That makes the arrow act weaker even though the shaft itself has not changed.
What FOC should I aim for?
Many hunters target 10–15%, while heavy-arrow builds often run 15–20% or more. Use the FOC that still flies well with your broadheads.
🧮 Related Calculators
Calculator results are planning estimates. Always confirm your setup with chronograph readings and real shooting.