Arrow Weight Calculator

Use the following arrow weight calculator to estimate arrow weight.

How to Determine Arrow Weight

One of the most important considerations in setting up a bowhunting setup is deciding on how heavy an arrow you want to shoot. Basically, arrow weight falls into three categories – light, medium, and heavy. Which you choose is based on several factors, including the game to be hunted, the conditions you expect to encounter on the hunt, and, just as important, your own personal preferences.

Heavier shafts, and overall arrow weight, are selected when larger game is the quarry. The author with a big Alaska brown bear.
Heavier shafts, and overall arrow weight, are selected when larger game is the quarry. The author with a big Alaska brown bear.

Use an Arrow Weight Calculator to Estimate

Many elements go into determining an arrow shaft’s final overall weight. When I build a hunting arrow, I use an arrow weight calculator to estimate how much my finished arrow weight will be before I get started, which lets me create the perfect arrow, with weight in mind, for a particular situation.

These factors are:

1) Grains Per Inch (GPI)

Arrow, and arrow point, weight are measured in grains. As a point of reference, 437.5 grains equals one ounce – or one grain weighs just 0.00228571 oz. All major arrow manufacturers list how much each of their different raw arrow shafts weighs in grains per inch.

A so-called light arrow might weigh 8 grains/inch, while heavier shafts can weigh north of 11 grains/inch. It’s important to remember that arrow weight is not arrow spine, which determines how much your shaft will flex when it leaves your bow. Regardless of weight, you have to choose the right arrow spine to ensure laser beam arrow flight.

2) Insert

Many arrow makers offer metal inserts – usually made of brass or aluminum — that can be inserted into the throat of the shaft to add overall weight and increase the weight/forward balance of the shaft. These inserts typically weigh between 50 and 75 grains, though some are heavier. Some inserts are customizable, that is, they can be easily shortened to drop their weight down a bit so you achieve the exact finished arrow weight you’re looking for.

3) Broadhead

The most common broadhead weights are either 100- or 125-grains, though much heavier heads are available.

(All of these elements are calculated in the arrow weight calculator).

4) Fletching

The standard three-fletch configuration with plastic hunting vanes will add somewhere between 15-30 grains of total weight, depending on the vane used.

5) Nock

A standard plastic nock will weigh somewhere around 5-10 grains. Depending on the manufacturer, a lighted nock will weigh 10-30 grains more than a standard nock.

6) Arrow Wraps

Adding a custom wrap to your shaft can increase overall arrow weight by 5-10 grains.

Overall Arrow Weight

What constitutes light, medium, and heavy shafts? Using my own 28-inch draw length as an example, a light hunting shaft would weigh approximately 350 grains. A medium-weight shaft would weigh in at 390-420 grains, while a heavy shaft would weigh 450 grains or more.

Bowhunters may choose a lighter shaft for increased initial raw arrow speed and a flatter trajectory, or when hunting thin-skinned game like pronghorn, and opt for a heavier shaft for larger, tougher game like elk and bears. Regardless, you must use a shaft with the correct spine for your draw weight/draw length; failure to do so will result in poor arrow flight and diminished accuracy.

Again, it’s always best to estimate an arrow’s weight with an arrow weight calculator before building or buying arrows for a specific species or hunt.

Light shafts may be chosen for thin-skinned game like pronghorn. Jared Pfeifer took this nice buck in New Mexico.
Light shafts may be chosen for thin-skinned game like pronghorn. Jared Pfeifer took this nice buck in New Mexico.

More on Weight

Arrow Weight Calculator Example

To increase kinetic energy, an arrow should be set up with more overall mass than the average arrow. This can be achieved multiple ways. First, choose an arrow shaft with a higher weight per inch (GPI). Standard carbon arrows tend to range in the 8 to 10 grains per inch range, but with aluminum/carbon hybrid arrows, an archer can achieve greater overall mass in their arrow. Easton Full Metal Jackets are a great option for archers wanting to achieve higher arrow mass while still being a smaller diameter shaft.

Easton offers the FMJ arrows in 4mm5mm, and 6mm. Smaller shaft diameter shafts have multiple benefits as well including less wind effects and less friction when entering the target. This will result in more accuracy and greater penetration. Another option to increase arrow weight is in the insert. Most arrow manufacturers have multiple options for insert materials and weights which can allow an archer to manipulate their overall arrow weight. Lastly, point weight can be increased to add more kinetic energy to an arrow. By increasing the weight of the arrow, it will also resist a change in direction more effectively. This means less wind drift during through the air. Keep in mind, when increasing weight in the front of an arrow, the dynamic arrow spine of the arrow will change. Be sure that your arrow will remain in proper spine range for your bow setup. Use an arrow weight calculator to estimate arrow weight.

For archers that may need to take shots at further range, many times for the western hunter, a proper balance between speed and kinetic energy is essential. This balance many times becomes a large debate for many due to what each individual views as important during the hunt. Speed is important to be able to reach out to the longer ranges, but arrow mass is essential to lethality and wind drift resistance. For most archers (27 to 30 inch draw length and 60 to 70 pound draw out of a modern compound bow), an arrow weighing between 420 to 450 grain tends to lead to a great balance of speed and energy to be effective for hunting. Archers should try to avoid hunting with arrows that weight in under 380 grains due to lack of kinetic energy.

Maximum Arrow Efficiency: Build Your Arrow for Success | Paeton Keller

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