Let-Off Percentage Calculator

Enter your bow's peak draw weight and holding weight to calculate let-off percentage, weight reduction at full draw, hold ratio, and cam efficiency.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter Peak Draw Weight (lb)
Input the maximum force (in pounds) required to pull your compound bow string back to its full draw position.
2
Enter Holding Weight (lb)
Provide the force (in pounds) you actually hold at full draw, after the bow's cams have rolled over and reduced the weight.
3
Review your results
The calculator will display the let-off percentage, the weight reduction, your holding weight, and the hold ratio.

Example Calculation

An archer wants to determine the let-off percentage of their compound bow, which has a peak draw weight of 70 lb and a holding weight of 14 lb.

Peak Draw Weight (lb)

Holding Weight (lb)

Results

80.0%

Tips

Measure Weights Accurately

Use a reliable bow scale to measure both your 'Peak Draw Weight' and 'Holding Weight' at full draw. Inaccurate measurements will lead to an incorrect let-off percentage, affecting your understanding of the bow's performance.

Adjust for Personal Comfort

While a higher let-off reduces holding weight, some archers prefer a lower let-off (e.g., 65-75%) for a more consistent feel and quicker release. Experiment to find what works best for your shooting style and discipline.

Consider Cam System Efficiency

Modern compound bows feature various cam systems (e.g., single cam, binary cam). The design of these cams directly influences the bow's let-off, draw cycle smoothness, and ultimately, its overall energy efficiency and holding comfort.

Unlocking Bow Performance: Your Let-Off Percentage Calculator

The Let-Off Percentage Calculator helps archers precisely quantify a critical aspect of compound bow performance: the reduction in draw weight at full draw. By inputting peak and holding weights, you gain insight into your bow's efficiency, aiding in tuning and technique. For example, a bow with a 70 lb peak draw weight and a 14 lb holding weight achieves 80% let-off, a key metric for comfort and accuracy in 2025 archery.

The Physics of Compound Bow Mechanics

Compound bows utilize eccentric cams and a system of cables to create a mechanical advantage throughout the draw cycle. This design allows the bow to store a significant amount of energy (peak draw weight), but then "let off" or reduce the force required to hold it at full draw (holding weight). This let-off effect, typically ranging from 65% to 90% in modern compound bows, enables archers to hold heavier peak draw weights for longer periods, improving aim and stability. The system efficiently transfers energy, making the bow easier to manage while still delivering high arrow speeds.

Weight Reduction = Peak Draw Weight (lb) - Holding Weight (lb)
Let-Off (%) = (Weight Reduction / Peak Draw Weight (lb)) × 100
Hold Ratio (%) = (Holding Weight (lb) / Peak Draw Weight (lb)) × 100

Let-Off (%) is the primary measure of the bow's mechanical advantage. Weight Reduction shows the absolute force difference.

💡 Understanding percentages is vital for archery. For other applications of percentage calculations, our Net Pay Percentage Calculator can help you determine your take-home income after deductions.

Analyzing a Hunter's Compound Bow

An avid hunter wants to fine-tune their compound bow for an upcoming season:

Peak Draw Weight (lb): 70 lbs
Holding Weight (lb): 14 lbs

Let's calculate the let-off and related metrics:

Calculate Weight Reduction: 70 lbs - 14 lbs = 56 lbs.
Calculate Let-Off Percentage: (56 lbs / 70 lbs) × 100 = 80%.
Calculate Hold Ratio: (14 lbs / 70 lbs) × 100 = 20%.

This bow provides an 80% let-off, meaning the archer only needs to hold 14 lbs at full draw, significantly reducing fatigue and allowing for steady aiming. The 20% hold ratio indicates a highly efficient system.

💡 Just as let-off helps archers achieve consistency, understanding statistical distributions can improve analytical accuracy. Our Normal Distribution Table Tool provides insights into data patterns and probabilities.

Let-Off for Different Archery Disciplines

Professionals in archery interpret let-off percentages differently based on their discipline. Target archers often prefer a moderate let-off (e.g., 65-75%) because it provides a more "connected" feel to the bowstring, which some believe aids in a cleaner, more consistent release, particularly important for precise shot timing. Conversely, hunters frequently opt for higher let-off (e.g., 80-90%) to maximize comfort. This allows them to hold at full draw for extended periods while waiting for an ethical shot opportunity, especially when facing challenging conditions like cold weather or shooting from a treestand, where stability and endurance are paramount.

The Physics of Compound Bow Mechanics

Frequently Asked Questions

What is 'let-off' on a compound bow?

'Let-off' on a compound bow refers to the percentage reduction in draw weight an archer experiences when holding the bow at full draw, compared to its peak draw weight. This mechanical advantage, achieved by the bow's eccentric cams, allows the archer to hold the string back with significantly less effort, improving stability and aiming time. For example, a bow with 80% let-off and a 70 lb peak draw weight would only require 14 lbs of holding weight at full draw. It's a key feature for comfort and precision in modern archery.

How does let-off affect an archer's shooting?

Let-off significantly affects an archer's shooting by reducing the physical strain of holding the bow at full draw, allowing for longer aiming times and greater stability. This is particularly beneficial in hunting scenarios, where an archer might need to hold their draw while waiting for a clear shot. It also reduces fatigue during practice sessions, helping to maintain consistent form. However, a very high let-off can sometimes lead to a less forgiving release, requiring more precise technique to avoid torque. It directly impacts comfort and accuracy.

What is a 'holding weight' in archery?

Holding weight, also known as 'valley weight,' is the actual amount of force, measured in pounds, an archer needs to exert to hold a compound bow at its full draw length. This weight is substantially less than the bow's peak draw weight due to the mechanical advantage provided by the cam system (let-off). For instance, a 70 lb peak draw weight bow with 80% let-off would have a holding weight of only 14 lbs. A lower holding weight allows for increased aiming time and reduced fatigue, which is crucial for accuracy.

What is a typical let-off percentage for compound bows?

Typical let-off percentages for modern compound bows range from 65% to 90%, depending on the bow's design and intended use. Hunting bows often feature higher let-off (75-90%) to maximize comfort during extended holds, while some target archery bows might have slightly lower let-off (65-70%) for a crisper feel and quicker release. Most manufacturers offer adjustable let-off settings to suit individual archer preferences and specific shooting disciplines. For example, an 80% let-off is a common and comfortable setting for many recreational and hunting archers.