Arrow Spine Calculator
Determine the correct arrow spine based on draw weight, draw length, point weight, and string type for optimal arrow flight.
Inputs
Results
Recommended Spine
550
How to Use This Calculator
- Enter your Draw Weight in pounds at your draw length.
- Set your Draw Length in inches.
- Enter the Point Weight in grains.
- Select your String Type (Dacron or modern Fast Flight).
- Review the Recommended Spine deflection value, Acceptable Range, and Over/Under-Spined thresholds.
How the result changes with Draw Length
| Draw Length | Recommended Spine |
|---|---|
| 21 | 800 |
| 25 | 650 |
| 29 | 550 |
| 33 | 450 |
What each input means
- Draw Weight
- Bow draw weight at your draw length.
- Draw Length
- Your measured draw length in inches.
- Point Weight
- Weight of the arrow point/tip in grains.
- String Type
- Dacron strings transfer less energy, needing weaker spine.
What each result means
- Recommended Spine
- Arrow spine deflection value (e.g., 400 = 0.400" deflection).
- Acceptable Range
- Range of spine values that should tune well.
- Over-Spined (too stiff)
- Spine value considered too stiff for your setup.
- Under-Spined (too weak)
- Spine value considered too weak for your setup.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersDraw Weight = 50, Draw Length = 28, Point Weight = 100, String Type = 2 = 4 input(s) provided
- Calculate Recommended SpineRecommended Spine550 = 550
- Calculate Acceptable RangeAcceptable Range500 - 600 = 500 - 600
- Calculate Over-SpinedOver-Spined450 = 450
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.
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