When it comes to the world of archery you will run into a lot of jargon which will inevitably be confusing when you head out to buy a compound bow. Some of these terms are risers, limbs, tillers and cams which refer to different parts of the bow, but others, such as draw length, IBO and draw weight refer to performance features of the bow. Let-off is one of those features that you’ll need to understand.
In the past when you drew a bow, particularly if you owned a longbow or a recurve bow you would have noticed that it takes a lot of strength to draw the bowstring back and then hold it while aiming for any length of time. Traditional bows have the most draw weight at the end of the draw which means it is particularly tiring if you try to hold the bow drawn for any length of time.
The compound bow has been designed to decrease the draw weight at the end of the drawstroke allowing the shooter more time to aim and release the arrow. To take the explanation further, as the bowstring is drawn back the weight increases steadily until you reach a certain point at which time the cam system steps in and it eases significantly so that by the end of the draw the shooter is only holding a fraction of the weight they were at the start of the draw..
The let-off rate of early compound bows was around 35-50% but nowadays the norm is more in the region of 75-80%, with some bows featuring an adjustable let-off. So a bow with a 70 lb draw weight and 80% let-off will converts to a draw weight of only 14 lbs.
It’s not always a good thing to have use a bow with super-high let-off at full draw because there is an increased likelihood to experience arrow movement whil in the shooting position. Some form of resistance is required to maintain a good natural alignment.
The let-off is listed by bow manufacturers as a percentage in their literature, sometimes you might see two numbers advertised next to the Let-off statistic. They will be “Effective” and “Actual” let-off. Let’s take a look at the difference between effective let-off and actual let-off.
Two figures are often listed under the Let-Off heading on a bow manufacturer’s compound bow specifications page. It may read something like Let-Off 65% Actual 70% Effective. What this is referring to is the disparity in draw weight change between drawing the bow and then the change in weight when letting the bowstring back down.
To calculate let-off you need to be able to measure two things: the minimum weight during draw and the maximum draw weight. These numbers differ depending on whether you are drawing the bow or letting the bow back down. As complicated as the second figure sounds, it’s the actual let-off or the let-off experienced when drawing the bow that you will be most concerned with. The figure you’re most likely going to see, though is the effective let-off.
Where it pays to remember the impact of effective let-off is after drawing the bow while letting it back down without an arrow fitted. Accidental dry-firing can occur as a result of the high effective let-off and the surprise with which it catches people unprepared. The sudden change in weight can rip the string out of unsuspecting fingers and you may be left with a shattered compound bow.
A final word on let-off comes with regard to the significance for those wanting their trophy listed in the Pope and Young Club’s record books. Until recently only those trophy’s taken with a let-off lower than 65% were included. This has since been changed in 2004 so that those taken with a higher let-off will be listed but an asterisk will be placed by the hunter’s name.
With any luck the previous explanation will help you when you go out to purchase a compound bow and you see the let-off figure you will understand the significance of the numbers. The higher the number, the lighter the draw. Now you just have to decide whether that will help or hinder your shooting accuracy.





















