Total Arrow Weight Calculator (Grains)
Total arrow weight equals shaft GPI times cut length, plus insert, point, nock, fletching and any wrap or collar. The finished arrow must weigh at least 5 grains per pound of draw weight.
Finished arrow weight decides kinetic energy, momentum, trajectory, noise, and whether your bow is being treated safely. This calculator adds up every component in grains and then applies the one rule in arrow building that is not a matter of preference: the 5 grain per pound minimum. Go under it and the tool turns red, because going under it can break bows.
The formula
Total weight equals GPI times cut length, plus every component you bolt to it. In grains, because that is the unit the entire industry uses and there are 7,000 of them in a pound. A worked example for a common hunting build:
- 28 inch shaft at 8.5 GPI: 238.0 grains
- Aluminium insert: 20 grains
- 100 grain field point: 100 grains
- Standard nock: 9 grains
- Three 2 inch vanes: 18 grains
- Wrap and glue: 12 grains
- Finished: 397 grains
On a 60 pound bow that is 6.6 grains per pound, comfortably above the floor and squarely in the range most hunting setups occupy. The single number people most often forget is the wrap, which is invisible once fletched and worth more than the nock.
The 5 grain per pound rule
This is the hard safety line in arrow building. The finished arrow must weigh at least five grains for every pound of peak draw weight. A 50 pound bow needs 250 grains, a 60 pound bow needs 300, a 70 pound bow needs 350.
The reason is that a bow stores a fixed amount of energy and the arrow is the only thing that can carry it away. A too-light arrow leaves too much of that energy in the limbs, cams and string, where it becomes vibration and shock. It is a partial dry fire, and repeated often enough it cracks limbs, splits cam bearings and delaminates. Every major bow manufacturer states this minimum, and every one of them voids the warranty below it.
Some manufacturers publish higher floors, and a handful of very aggressive target bows specify 6 grains per pound or more. Check your own bow's manual rather than assuming five is universally permitted, and if you are anywhere near the line, weigh the finished arrow on a scale instead of trusting the box.
Typical component weights
Use these to sanity-check a build before the parts arrive. Every figure is a published range across common products, not a single model.
| Component | Typical weight | Notes |
|---|---|---|
| Target carbon shaft | 5.5 to 8.0 GPI | Thin diameter, light, indoor and outdoor target |
| Hunting carbon shaft | 8.0 to 10.5 GPI | The mainstream range for compound hunting builds |
| Heavy or traditional shaft | 11 to 14 GPI | Wood and heavy carbon for penetration builds |
| Aluminium insert | 10 to 25 gr | The default on most factory arrows |
| Brass insert | 50 to 100 gr | The cheapest way to add front weight and raise FOC |
| Half-out or collar | 10 to 30 gr | Adds durability at the front end |
| Field point | 75 to 150 gr | 100 gr is the industry default |
| Broadhead | 100 to 200 gr | Match field point weight for practice |
| Standard nock | 6 to 12 gr | Pin nocks sit at the light end |
| Lighted nock | 15 to 25 gr | Adds rear weight, so it lowers FOC slightly |
| Three 2 in vanes | 15 to 18 gr | The common low-profile hunting choice |
| Three 4 in vanes | 22 to 26 gr | More steering for fixed blade broadheads |
| Three feathers | 8 to 15 gr | Lighter than vanes, favoured on traditional builds |
| Arrow wrap | 8 to 20 gr | The component people forget most often |
Choosing a target weight
Once you are safely above the floor, weight is a preference with real consequences on both sides. A useful way to frame it is grains per pound rather than raw grains, because it normalises across draw weights:
- 5 to 6 gr/lb. Speed-first. Flat trajectory, most forgiving of range errors, loudest and hardest on the bow. Legal but with no margin.
- 6 to 7 gr/lb. The general purpose range. Most factory hunting arrows land here on a 60 to 70 pound bow.
- 7 to 8 gr/lb. Quieter, better downrange energy retention, a small trajectory cost. A very common deliberate choice.
- 8 gr/lb and up. Penetration-first. Noticeably quiet, noticeably slow, and best paired with high front of centre and short shot distances.
Whatever you land on, feed it into the kinetic energy calculator to see what the finished arrow actually delivers, and the arrow speed calculator to see what the weight change costs in feet per second.
The only honest way to compare a 400 grain and a 480 grain build is to shoot both at the same distance into the same target and look at the group, the noise and the point of impact shift. A target rated for high speeds and for broadheads lets you carry that comparison all the way through to the head you actually intend to use, which is where weight differences finally show up.
Weight, spine and FOC move together
The most common mistake after building a heavier arrow is assuming the tune survived. It usually did not. Most of the added mass goes on the front, and front weight weakens dynamic spine at roughly the equivalent of five pounds of bow weight for every 25 grains. A build that gained 75 grains at the point has effectively moved a full spine group.
The same change raises front of centre, which is normally welcome, but it is worth measuring rather than assuming. Run the finished arrow through the FOC calculator and re-run the spine calculator with the new point weight before you commit to a full dozen. Building one arrow first and shooting it is always cheaper than building twelve.
Related tools
- Kinetic energy calculator: what the finished weight delivers
- Arrow cut length calculator: settle cut length before you multiply by GPI
- Arrow speed calculator: what the added grains cost in fps
- Best archery rangefinders: heavier arrows make exact distance matter more
Frequently asked questions
How do you calculate total arrow weight?
Multiply the shaft grains per inch by the cut length in inches, then add the insert, point, nock, fletching, wrap and any collar. A 28 inch shaft at 8.5 grains per inch is 238 grains, and adding a 20 grain insert, 100 grain point, 9 grain nock and 18 grains of vanes brings it to 385 grains. Everything is measured in grains, and there are 7,000 grains in a pound.
What is the minimum safe arrow weight for my bow?
Five grains of finished arrow weight per pound of draw weight is the near-universal manufacturer minimum. A 60 pound bow needs at least 300 grains and a 70 pound bow needs 350. Shooting lighter behaves like a partial dry fire because the arrow cannot absorb the stored energy, and it will void essentially every bow warranty on the market.
How heavy should a hunting arrow be?
Most hunting builds land between 400 and 500 grains finished, which on a typical 60 to 70 pound bow works out to 6 to 8 grains per pound. That range keeps the bow quiet, retains energy downrange, and stays fast enough for practical shot distances. Heavier arrows penetrate better and are quieter, lighter ones shoot flatter and forgive range errors more.
Does arrow weight affect accuracy?
Not directly, but heavier arrows are more forgiving in wind and less sensitive to a slightly imperfect release, while lighter arrows shoot flatter and punish range errors less. The bigger accuracy factor is whether the finished weight matches the spine you chose, because adding point weight to increase mass also weakens dynamic spine and can push a tuned arrow out of tune.
What is grains per inch and where do I find it?
Grains per inch, or GPI, is the mass of one inch of bare shaft and it is printed on every box of arrows and listed on every spec sheet. Hunting shafts typically run 8 to 10 GPI, target shafts 5.5 to 8, and heavy traditional shafts above 11. Multiply GPI by your cut length to get the bare shaft contribution to total weight.
Should I weigh my finished arrows or trust the calculator?
Use the calculator to plan a build and a grain scale to verify it. Component weights vary by a few grains from their stated figures, glue adds two to five grains, and shafts within the same dozen can differ. If you are matching arrows for consistency, a scale accurate to 0.1 grain is the tool that actually settles it. Sort and match rather than chasing an exact number.
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.