Looking to get an estimate of your bow’s arrow speed based on your bowhunting setup? Try our arrow speed calculator below!
Use the tool above to calculate the speed of your arrow!
When it comes to archery, IBO stands for International Bowhunters Organization.
What is IBO Speed and how is it calculated?
You might have seen where compound bows have an IBO rating.
But, what does that really mean?
Well, the IBO speed of a bow is calculated using a bow with a draw weight of 70 lbs, a draw length of 30 inches, and an arrow weight of 5 grains per pound of draw weight. So, that would mean a 70-lb draw weight would be shooting an arrow that weighs 350 grains (70 x 5 = 350).
That arrow is then shot through that bow through a chronograph, which measures the arrow speed. The average speed becomes known as the IBO rating of that particular bow.
The problem with IBO ratings
The problem with IBO ratings, however, is that they are not typical of most hunters’ setups.
For example, a 30-inch draw length is rather long for the average archer. Also, an arrow weight of 350 grains is simply not typical of most hunting setups. And, with high FOC arrows gaining popularity, the arrow’s grains per inch is often significantly greater.
So, when using the arrow speed calculator above, you must understand that the IBO rating you enter is based on this premise. The calculator will give you an estimate of how changing the inputs that make up IBO could affect your arrow speed.
The arrow speed calculator makes the following assumptions:
- Every inch of draw length under 30″ will subtract 10 ft per second from the IBO value.
- Every inch of draw length above 30″ will add 10 feet per second to the IBO value.
- Every 3 grains of total arrow weight above draw weight multiplied by 5, will subtract 1 foot per second from the IBO value.
- Every 3 grains of additional weight on the bow string will subtract 1 foot per second from the IBO value.
Other Inputs for Arrow Speed Calculator
After you have entered your bow’s manufacturer rated IBO, enter the following information:
- The draw weight of your bow in pounds.
- The draw length of your bow in inches
- The arrow weight in grains (includes fletchings, wraps, inserts and also points/broadheads
- Total string accessory weights in grains (peep, tube, silencers, etc.). For your reference, an estimated peep only weight is 20 grains, and a peep + tube is 45 total grains.