Archery String Length Calculator
Calculate the correct bowstring length for your recurve or longbow.
Find string length from bow length (AMO measurement).
The correct string length determines your bow’s brace height — the distance from the grip to the string at rest. Incorrect string length results in incorrect brace height, which affects performance and potentially bow safety.
AMO (Archery Manufacturers Organization) convention: AMO bow length is measured along the back of the bow from tip to tip. AMO string length is typically 3 inches less than AMO bow length for recurve and longbows.
The formula: String length = AMO bow length − 3 inches (recurve/longbow)
Brace height by bow type:
- Recurve (competition, 66–70 in): 8.5–9.5 inches brace height
- Recurve (hunting, 58–64 in): 7.0–8.5 inches brace height
- Longbow: 6–7 inches (varies by design)
- Traditional/selfbow: 5–6 inches
Effect of string length on brace height:
- Shorter string = higher brace height = more forgiving, slower
- Longer string = lower brace height = less forgiving, faster
Twist adjustment: Recurve strings can be twisted to fine-tune brace height. Adding twists shortens the string slightly, raising brace height. Untwisting lowers brace height. Standard starting twists: 12–16 for a 62-inch string.
Compound bow strings: Compound bows use a different measurement system. Always replace compound strings with factory-specified lengths — incorrect length changes draw weight and cam timing significantly.