Visitor Monitoring
Dynamic Spine Calculator
Find the perfect arrow to maximize your shooting! Match the dynamic spine of both bow and arrow for optimal arrow performance.

PLEASE NOTE: This is a mathematical formula for selecting a bow/arrow combination. In theory, the results from the data you enter should work perfectly, BUT in real world use, variations will happen. This can be from your personal shooting form (creeping, plucking the string, etc), or incorrect data entered (bow having a different center cut than what is listed, bow weight different than what is printed on bow, etc).

3Rivers does not guarantee results provided by this tool. We ALWAYS recommend getting a shafting test kit to confirm a set up prior to buying a set spine.
See ALL Test Kits HERE. Feel free to call our Tech line Monday-Thursday 9am-8pm EST and Friday 9-5 at 866-587-9501.
1. Enter Bow Information      2. Enter Arrow Information      3. Click Calculate
Enter Information
Enter Bow Information
1. Select Bow Make & Model
2. Enter Factory Bow Weight (pounds)
3. Enter Factory Draw Length (inches)
4. Enter Your Actual Draw Length (inches)
5. Select Center Cut Measurement
6. Does your riser have a strike plate?
    -If Yes, enter its thickness (inches) thickness
7. Select Bow String Material
Enter Arrow Information
1. Select Arrow Model & Deflection
    -For Wood or Other, enter AMO static spine
      (2# @ 26") (enter exact poundage, for 60# use 60)
static spine
    -For Wood/Other, enter shaft grains per inch (GPI) GPI
    -For Wood/Other, enter shaft diameter
      Enter in decimal value, 11/32" = 0.34375
shaft diameter
2. Enter Arrow Length (inches)
      (measure from back of point to valley of nock)
3. Enter Point Weight (grains)
4. Enter Insert Weight (grains)
5. Are your shafts footed?
    -If Yes, enter length (inches) and weight (grains) footing length
  footing weight
6. Enter Total Nock Weight (grains)
      (nock, bushing, collar, etc.)
7. Select Fletching Type
    -If Other, enter total feather weight (grains) weight
Personal Form Calibration
Because personal form can alter dynamic spine, the calculator may need to be calibrated to accommodate your shooting form. Personal Form calibration should only be changed from zero if:
  • You are 100% confident an existing bow and arrow setup is consistently on target from group tuning, but when using this calculator to confirm your setup, the bow and arrow results have a variance of greater than 2 lbs. To calibrate, enter a number from -15 to 15. That will change the dynamic bow spine to be within 2 lbs. of the dynamic arrow spine.
  • Bow and Arrow combinations used from results of this calculator are not providing perfect arrow flight, and other factors, such as brace height, have been tuned. To calibrate, enter a number from -15 to 15. That will change the dynamic bow spine to be within 2 lbs. of the dynamic arrow spine.
Note: Leave at ZERO if none of the above apply. 1. Enter Personal Form Calibration
McAfee SECURE sites help keep you safe from identity theft, credit card fraud, spyware, spam, viruses and online scams Click to verify BBB accreditation and to see a BBB report Trust Us Facebook page for 3Rivers Archery YouTube videos for 3Rivers Archery Google+ page for 3Rivers Archery
 Customer Service    About Us    Product Details    Extra Features    Top Categories

 My Account 
 Check Order Status 
 Shipping Information 
 Return Policy 
 Privacy Statement 
 Terms of Use 
 3Rivers Archery
 PO Box 517
 607 HL Thompson Jr Dr
 Ashley, IN 46705

 Request a Catalog 
 Learn More About Us 
 Top Searches 
 Gift Certificates 
 Dealer Information 
 Email Sign Up 
 Trophy Room 
 3D Shoots 
 Arrow Whiz 
 Military Discount 
Read Our Blog
 Kid bow sets 
 Recurve bows 
 Longbow bows 
 Carbon arrows 
 Wood arrows 
 Youth Archery 
©2015 Three Rivers Archery Supply, Inc. All Rights Reserved.
No part of this web site may be copied or reproduced without the express written permission of Three Rivers Archery Supply, Inc.
Ask The Experts Ask the Experts at 3Rivers Archery
Blank space
Order Status Gift Cards Free Catalog Customer Service Sale Items 3Rivers Archery Customer Service and Sale Items
Sign In 3Rivers Archery Welcome and Sign In
($0.00 / 0 items) View Cart at 3Rivers Archery
Background Blank
100% Satisfaction Guarantee 3Rivers Archery 100% Satisfaction Guaranteed
Leading the industry. EXPERIENCE (over 250 years.) KNOWLEDGE (experts at being THE EXPERTS.) AMERICAN PRODUCT SELECTION (over 90% of products Made in the USA.)