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How to Calculate Draw Length and Arrow Length for Beginners
If you want to improve your accuracy with a bow, take the time to calculate your optimal draw length and arrow length. The following calculator allows you to estimate your draw length to begin practicing quickly.
Several methods exist for estimating draw length:
- Measure and divide
- Arrow method
- ATA draw length standard
Some methods are more accurate than others. For increased accuracy, calculate your draw length using each method and average the results. The averaged size should be closer to your proper draw length.
Measure and Divide
The “measure and divide” method is one of the simplest ways to estimate your draw length with a measuring tape. It also tends to provide the most accurate results without measuring your draw length directly.
Your wingspan (arm span) is the distance from fingertip to fingertip with your arms extended at shoulder height. To get more accurate results using this method, measure your wingspan against a wall. Stand with your back against the wall, raise your arms, and place a mark on the walls where your fingers end.
To calculate your draw length, divide your wingspan measured in inches by 2.5 and round up to the nearest half-inch. For example, if you have a wingspan of 70 inches, your draw length would be 28 inches.
An alternative formula involves subtracting 15 from your wingspan and dividing the result by 2. However, if you are shorter or taller than the average person, this formula may provide a slightly different outcome.
While these methods are simple, the estimated draw length’s accuracy depends on the accurate measurement of your wingspan. You may want to get someone to measure for you, as measuring yourself may skew the results.
The arrow method is commonly used in archery shops to help customers estimate their draw lengths. It involves using an arrow with measurements marked along the length of the shaft. You draw the bow and check the measurements to determine the draw length.
However, the accuracy of this method relies on the arrow being correctly marked. The shooter also needs to maintain proper form. If your elbow is fully extended or you draw past the corner of your mouth, you will get a long draw length.
ATA Draw Length Standard
The Archery Trade Association (ATA) draw length standard is determined using a bow without an arrow.
Draw the bow to the proper anchor position and measure the distance from the nocking point (where your hand pulls the string) to the pivot point on the back of the bow. You then add 1.75 inches to the total.
How to Determine Arrow Length
The recommended arrow length is typically the draw length plus 1 to 2 inches. However, some people prefer using arrows that are up to one inch shorter or longer than the draw length.
A shorter arrow can fly faster but also requires increased stability to maintain accurate flight. A longer arrow tends to retain velocity and is more forgiving, which is why many archers recommend that beginners start with a slightly longer arrow length.
Why Does Draw Length Matter?
A long draw length forces you to lean your head further back, resulting in lousy form and increased bow tension. If the draw length is too short, you lose consistency and accuracy.
To quickly estimate your draw length, use the calculator on this page. You may also want to have someone assist with the measurements and consider averaging each method’s results.
What Happens If Draw Length Is Too Short?
If the draw length of your bow is too short, you are “under-bowed.” A shorter draw length can reduce the velocity of the arrow. The decreased wind resistance makes the arrow more susceptible to gusts of wind and obstacles such as leaves and branches.
An optimal draw length is needed for proper form. This typically involves keeping the bow arm’s elbow straight and relaxed or slightly bent but never fully locked or significantly bent.
A shorter draw length keeps the archer from extending the bow arm far enough. With the bow arm bunched up, the archer loses speed. Reducing arrow speed limits accuracy, especially at greater distances or in heavy brush.
Each one-inch reduction in draw length lowers the arrow’s velocity by about 10 feet per second (fps). When an arrow travels at a slower speed, leaves, branches, and wind can easily influence its trajectory.
A short draw length may also increase the risk of overdrawing the bow. The mechanical stop on most compound bows makes it difficult to draw the string back further than the draw length. However, a short draw length may lead the archer to forcibly overdraw, placing more strain on the bow and the archer.
Overdrawing is a greater threat to recurve bows, as it may cause delamination. The limbs of recurve bows are made using multiple layers of wood, fiberglass, or other materials. The splitting of the layers is called delamination and is often due to overdrawing.
Archers can detect if their draw length is too short by paying attention to their form. If they cannot keep their bow arm properly extended with the string drawn to the cheek, the draw length is likely too short.
The easiest way to determine if the draw length is too short is to use a calculator to estimate the ideal draw length based on your arm span.
How Do I Know If My Draw Length Is Too Long?
If the draw length is too long, the archer is likely to under-draw the bow. Under-drawing reduces speed and accuracy. After drawing the bow and bringing the release hand back, the string should reach maximum tension for its draw length. With a longer draw length, the bowstring still has flack, which is called “under-drawing.”
Compound bows are only meant to be shot from a full draw, which means that the bowstring should be pulled to the bow’s specified draw length. The bow has a mechanical stop that keeps the bowstring from extending beyond the draw length.
As you bring back the bowstring, you can feel the tension of the string increase. The proper form typically involves keeping the bow arm straight or slightly bent with a relaxed elbow while the release hand is brought back to the cheek or jawline.
After achieving the right form, the bowstring should be fully taut. If it is not yet extended to the full draw position, you are under-drawing. The draw length is too long for your arm span. An improperly long draw length may also cause the shooter to arch their back too much.
Instead of under-drawing, your effort to pull the bowstring back may force you to arch your back at more of an angle. This throws off your sight by bringing your grip above eye level.
You may also bring your release hand back further and straighten or lock your bow arm to pull the bowstring to its full draw length. Locking your elbow places more pressure on the joints, which may cause injuries. Extending your release hand too far back increases the risk of hitting your forearm with the bowstring and impacts your accuracy.
The optimal draw length for each person is related to their arm span. To determine if the draw length is too long, archers should use a draw length calculator.
Can You Shoot a Shorter Draw Length?
Many archers choose to use a shorter draw length to use shorter, lighter arrows. A shorter arrow can travel with greater accuracy as the stiffer spine flexes less than a longer spine.
Archers may also use a shorter draw length to alter the performance of their current choice of arrows. For example, an experienced archer may choose to slightly overdraw a bow with a shorter draw length.
For each inch that the archer overdraws the bow, they weaken the arrow’s spine equal to about the equivalent of adding three to four pounds of draw weight to the bow. This adds speed without changing the arrow length.
While a shorter draw length offers several advantages, it can also lead to a few potential risks. A short draw length may keep the archer from maintaining proper form. If the draw length is too short, the archer stays bunched up.
The bow arm’s elbow stays bent at more of an angle instead of keeping the elbow extended and slightly relaxed. Without proper form, the bow or elbow may rotate enough for the string to hit the arm upon release. This is called a string slap.
The shorter draw length also decreases the speed of the arrow. While the accuracy increases, the decreased speed makes the arrow more susceptible to any disturbances in its path, including wind, leaves, and branches. Using a draw length that is too short may also cause the archer to overdraw. With a recurve bow, the strain of overdrawing may eventually cause the limbs to split and break.
The bottom line is that a shorter draw length is not recommended for beginners. Shooting with a shorter draw length is typically used as a way for more experienced archers to utilize shorter arrows for increased accuracy, especially at short to medium distances.
Does Draw Length Affect Draw Weight?
Draw length directly influences the draw weight of recurve bows. As you increase the draw length, you increase the draw weight. However, compound bows have set draw weights and poundages.
Draw length is the distance from the nock point on the bowstring to the pivot point on the grip plus 1.75 inches when the bowstring is fully drawn. The draw weight is measured in pounds and based on the pulling force needed to fully draw a bow with a draw length of 28 inches.
A bow with a longer draw length requires more force to achieve full draw than a bow with a shorter draw length. For each inch over 28 inches, the draw weight increases by 2.5 pounds.
For example, a 35-pound recurve bow has a draw weight of 35 pounds when the bowstring is pulled to 28 inches. Increasing the draw length to 30 inches increases the draw weight to 40 pounds.
While compound bows have set draw weights, the weight is often adjustable. Some compound bows allow you to adjust the weight across a 50-pound range, while others only offer a 10-pound range. Increasing or decreasing the draw weight of the compound bow does not significantly change the draw length. However, changing the draw weight does slightly alter the brace height.
The brace height is the distance between the pivot point on the grip and the string when the string is not drawn. Tightening the limbs on the bow to increase the draw weight brings the string slightly closer. As the brace height changes, the draw length may change by a few millimeters.
Most archers choose to take their compound bows to bow technicians at archery shops to adjust the draw weight. Adjusting the draw weight involves tightening or loosening the limb bolts. If the limb bolts are loosened too far, the bolts may be projected from the bow, causing damage to the bow or the person adjusting the bow.
What Is the Average Draw Length?
The average draw length for recurve bows and compound bows is 28 inches. 28 inches is the standard used to determine the draw weight for recurve bows. The draw weight is based on the required pulling force to fully draw a bow with a draw length of 28 inches.
The most common method for determining the ideal draw length involves dividing your arm span by 2.5. The typical adult’s arm span is almost identical to their height, leading many manufacturers to list recommended draw lengths based on height.
The average adult male is about 5’10” (70 inches). 70 inches divided by 2.5 is 28 inches. The average height of an adult female is 5’4″ (64 inches). 64 divided by 2.5 is 25.6. After rounding up to the nearest half-inch, the optimal draw length would be 26 inches.
While the height-to-arm span ratio is typically 1:1, some individuals have longer arms slightly. This may be due to medical conditions that result in height loss, such as spinal conditions or aging. For the most accurate starting point for a draw length, individuals should measure their arm span and use a draw length calculator.
Beginners should typically start with the recommended draw length based on their arm span. However, many archers eventually decide to tweak their draw length with practice and experience to suit their preferences.
Finding the right draw length can help you shoot better. However, archers must also consider the ideal draw weight. The average draw weight of a compound bow for an adult male is 55 to 65 pounds. The average draw weight for a recurve bow is 40 to 55 pounds.
For women, the averages are 30 to 40 pounds (compound bow) and 25 to 35 pounds (recurve bow). Beginners often start with a lighter weight, allowing them to work on their form and technique before moving up to a heavier bow.