Bow String Length Calculator - Calculate Your Perfect Archery String

Calculate Your Bow String Length

Select Units:

Bow Type: Choose the type of bow for accurate calculation.

AMO Bow Length: Enter the Archery Manufacturers Organization (AMO) bow length. This is typically printed on the bow or riser. Please enter a valid positive number.

Calculation Results

0.0 in

This is the recommended string length for your bow type and AMO length.

AMO Bow Length Input: 0.0 in

Bow Type Selected: Recurve Bow

Difference from AMO Length: 0.0 in

Percentage Shorter: 0.0%

Bow String Length Visualization

Graph showing calculated string length (Y-axis) versus AMO Bow Length (X-axis) for Recurve and Longbows. All values are in inches.

What is a Bow String Length Calculator?

A bow string length calculator is an essential tool for archers, helping to determine the correct string length required for a specific bow. Unlike many assume, the string length is typically shorter than the bow's stated AMO (Archery Manufacturers Organization) length. This shorter length is necessary to create the proper tension and achieve the optimal brace height when the bow is strung.

This calculator is primarily designed for traditional bows such as recurves and longbows, where a general rule of thumb can be applied to estimate string length based on the bow's AMO length. Compound bows have highly specific string and cable lengths determined by the manufacturer's cam system, making a generic calculator unsuitable for them.

Who should use this calculator? Anyone looking to buy a replacement string, build a new string, or simply verify the correct string length for their traditional bow. Using the wrong string length can lead to poor arrow flight, excessive noise, increased wear on the bow, and even safety hazards.

Bow String Length Formula and Explanation

For traditional bows, the formula for calculating bow string length is generally a simple subtraction from the bow's AMO length. The specific amount subtracted varies slightly between recurve and longbows due to their different limb geometries and desired brace heights.

The general formula is:

Calculated String Length = AMO Bow Length - X

Where 'X' is a factor that depends on the bow type:

For **Recurve Bows**: X is typically **3 inches (or 7.62 cm)**.
For **Longbows**: X is typically **2 inches (or 5.08 cm)**.

These values are common industry standards and provide a good starting point for achieving the recommended brace height for most traditional bows. Slight adjustments might be needed based on individual bow characteristics, string material, and personal preference for brace height.

Variables Used in This Bow String Length Calculator:

Key Variables for Bow String Length Calculation
Variable	Meaning	Unit	Typical Range
AMO Bow Length	The Archery Manufacturers Organization standard length of the bow, measured from string groove to string groove along the limb.	Inches / Centimeters	48 - 70 inches
Bow Type	The design category of the bow (e.g., Recurve, Longbow). Influences the 'X' factor for string length.	N/A (Categorical)	Recurve, Longbow
Calculated String Length	The estimated length of the bow string required for optimal performance.	Inches / Centimeters	45 - 68 inches

Practical Examples for Bow String Length Calculation

Let's look at a couple of real-world scenarios to illustrate how the bow string length calculator works.

Example 1: Recurve Bow String Length

**Bow Type:** Recurve Bow
**AMO Bow Length:** 62 inches
**Calculation:** 62 in - 3 in = 59 in
**Result:** The recommended string length is **59 inches**.

This string length will provide a good starting point for achieving the proper brace height for a 62-inch recurve bow.

Example 2: Longbow String Length

**Bow Type:** Longbow
**AMO Bow Length:** 68 inches
**Calculation:** 68 in - 2 in = 66 in
**Result:** The recommended string length is **66 inches**.

For a longbow, the string is typically only 2 inches shorter than the AMO length, resulting in a 66-inch string for a 68-inch bow.

Example 3: Unit Conversion (Centimeters)

**Bow Type:** Recurve Bow
**AMO Bow Length:** 157.5 cm (equivalent to 62 inches)
**Calculation:** 157.5 cm - 7.62 cm = 149.88 cm
**Result:** The recommended string length is approximately **149.9 cm**.

The bow string length calculator handles unit conversions automatically, ensuring you get accurate results in your preferred measurement system.

How to Use This Bow String Length Calculator

**Select Your Units:** Choose "Inches (in)" or "Centimeters (cm)" from the "Select Units" dropdown based on your preference. All inputs and outputs will adjust accordingly.
**Choose Bow Type:** Select either "Recurve Bow" or "Longbow" from the "Bow Type" dropdown. This is crucial as the calculation factor 'X' changes based on bow type.
**Enter AMO Bow Length:** Input the Archery Manufacturers Organization (AMO) bow length into the designated field. This measurement is often printed on the bow's riser or limbs. Ensure it's a positive numerical value.
**View Results:** As you type, the bow string length calculator will instantly display the "Calculated String Length" in the primary result area, along with intermediate values like the difference from AMO length and percentage shorter.
**Interpret Results:** The primary result is your recommended string length. You can also see how much shorter the string is compared to your bow's AMO length.
**Copy Results (Optional):** Click the "Copy Results" button to quickly copy all calculated values to your clipboard for easy record-keeping or sharing.
**Reset Calculator (Optional):** Use the "Reset" button to clear all inputs and revert to default settings.

Remember, while this bow string length calculator provides an excellent estimate, always consult your bow manufacturer's recommendations if available, and fine-tune brace height as needed.

Key Factors That Affect Bow String Length

While our bow string length calculator provides a solid starting point, several factors can influence the ideal string length and final setup for your archery equipment:

**1. Bow Type:** As seen in the formula, recurve bows typically require a string 3 inches shorter than AMO length, while longbows need a string 2 inches shorter. This is the most significant factor for determining string length.
**2. AMO Bow Length:** The official AMO length of your bow is the primary input. It dictates the base from which the string length is calculated. An accurate AMO measurement is critical for getting the correct string length.
**3. Desired Brace Height:** Brace height (the distance from the string to the deepest part of the grip) is a critical tuning parameter. A slightly longer or shorter string can be used to fine-tune brace height within the manufacturer's recommended range, impacting arrow flight and noise.
**4. String Material:** Different string materials (e.g., Dacron, Fast Flight, Dyneema) have varying degrees of stretch. Newer, low-stretch materials may require a string that is precisely the calculated length, while older materials might stretch slightly over time, potentially requiring a slightly shorter initial string.
**5. Manufacturer's Recommendations:** Always prioritize the bow manufacturer's specific string length and brace height recommendations if they are available. These are tailored to the exact design of your bow.
**6. Personal Preference & Tuning:** Advanced archers may slightly adjust string length (and thus brace height) to achieve specific tuning goals, such as optimizing arrow flight, reducing hand shock, or minimizing string slap.

Frequently Asked Questions (FAQ) About Bow String Length

Q: What is AMO Bow Length, and why is it important for the bow string length calculator?

A: AMO (Archery Manufacturers Organization) Bow Length is a standardized measurement of the bow's length. It's crucial because string length formulas are typically based on this standard. It's usually measured from the string nock groove on one limb to the string nock groove on the other, following the curve of the limbs. It ensures consistency across different manufacturers and helps in finding the correct bow string length.

Q: Why is the bow string length always shorter than the bow's AMO length?

A: The string needs to be shorter than the unstrung bow to create tension in the limbs when strung. This tension is what stores energy and propels the arrow. The difference in length determines the brace height, which is the distance from the string to the deepest part of the bow's grip. A proper brace height is vital for efficient shooting, quiet operation, and preventing string slap.

Q: Can I use this bow string length calculator for compound bows?

A: No, this bow string length calculator is specifically designed for traditional recurve and longbows. Compound bows utilize complex cam systems that require very precise string and cable lengths, which are unique to each bow model and manufacturer. Always refer to your compound bow's specific owner's manual or manufacturer's specifications for string and cable lengths.

Q: What if my bow's AMO length isn't printed on it? How do I measure it?

A: If your bow's AMO length isn't marked, you can typically measure it yourself. For a recurve, measure from the tip of one string groove to the tip of the other, following the limb curves. For a longbow, it's usually a straight-line measurement from tip to tip. However, consulting the bow's manufacturer or a reputable archery pro shop for assistance is always recommended to ensure accuracy when determining bow string length.

Q: How important is brace height, and how does it relate to string length?

A: Brace height is extremely important. It affects arrow flight, bow noise, hand shock, and overall shooting feel. A string that is too long will result in a low brace height, potentially causing string slap and inconsistent arrow flight. A string that is too short will result in a high brace height, making the bow harder to draw and potentially less efficient. String length directly determines brace height, so getting the string length right helps achieve the optimal brace height.

Q: What units should I use for the bow string length calculator?

A: You can use either inches (in) or centimeters (cm) with this calculator. The unit switcher allows you to choose your preferred system. The calculations convert internally to ensure accuracy regardless of your display unit. Most bow manufacturers in the US list AMO lengths in inches, while metric units are common elsewhere for bow string length measurements.

Q: What happens if my string is slightly too long or too short?

A: A string that is too long will result in a low brace height, which can cause the string to hit your armguard (string slap), make the bow noisy, and lead to inconsistent arrow flight. A string that is too short will result in a high brace height, making the bow feel stiffer, harder to draw, and potentially less efficient. Small adjustments can be made by twisting or untwisting the string to fine-tune brace height, but significant errors require a different string.

Q: How often should I replace my bow string?

A: The lifespan of a bow string depends on material, usage, and maintenance. Generally, traditional bow strings should be inspected regularly for fraying, wear, or damage. Many archers replace their strings annually or every few thousand shots, especially if they notice a drop in performance or visible wear. Proper waxing and storage can extend string life and ensure consistent bow string length.

Related Archery Tools and Resources

Explore more of our archery calculators and guides to enhance your shooting experience and knowledge, including tools related to archery draw length and bow draw weight:

Archery Draw Length Calculator: Find your perfect draw length for optimal form and power, complementing your bow string length.
Bow Draw Weight Calculator: Understand the force needed to draw your bow, which can influence your overall bow setup.
Arrow FOC Calculator: Calculate Front of Center (FOC) for improved arrow stability and penetration, a key aspect of arrow tuning.
Arrow Speed Calculator: Estimate your arrow's velocity based on bow and arrow specifications, another crucial performance metric.
Archery Glossary: A comprehensive guide to common archery terms and definitions, helping you understand concepts like AMO bow length and brace height.
Bow Maintenance Tips: Learn how to care for your archery equipment, including your bow string, to ensure longevity and peak performance.