Enter the bow’s rated draw weight (usually specified at a 28 in draw length) and your draw length. The calculator will estimate the bow draw weight at your draw length.

Bow Draw Weight Calculator

Tip: If you don’t know your draw length, use the Find Proper Draw Length tab. When you calculate there, this tab can auto-fill your draw length.

Bow Draw Weight Formula

The following two example problems outline the steps and information needed to estimate bow draw weight at a specific draw length.

BDW = RDW + (DL - 28)\times G

Variables:

  • BDW is the bow draw weight at your draw length (lbf)
  • RDW is the bow’s rated draw weight (typically rated at a 28 in draw length) (lbf)
  • DL is your draw length (in)
  • G is an estimated weight gain per inch (lbf/in). For many recurve/longbow bows near 28 in, a common rule-of-thumb is about 2–3 lbf per inch, but it varies by bow and can increase (“stack”) at longer draw lengths.

To estimate bow draw weight at your draw length, start with the rated draw weight at 28 inches, then add (your draw length − 28) multiplied by the estimated weight gain per inch. (If your draw length is less than 28 in, the estimated draw weight will be lower.)

How to Calculate Bow Draw Weight?

The following steps outline how to estimate bow draw weight at a given draw length (using the rule-of-thumb linear adjustment above).

Example Problem #1:

  1. First, determine the bow’s rated draw weight at 28 in (RDW).
    • RDW is given as: 40 lbf
  2. Next, determine your draw length (DL).
    • DL is given as: 30 in
  3. Then, choose an estimated weight gain per inch (G) appropriate for the bow (rule-of-thumb).
    • G is given as: 2.5 lbf/in
  4. Finally, calculate the bow draw weight using the equation above.

BDW = RDW + (DL – 28) × G

The values provided above are inserted into the equation below and computed.

BDW = 40 + (30 – 28) × 2.5 = 45.00 (lbf)

Example Problem #2: 

For this problem, the variables required are provided below:

RDW (rated draw weight at 28 in) = 35 lbf

DL (your draw length) = 26 in

G (estimated weight gain per inch) = 2.5 lbf/in

Test your knowledge and check your answer with the calculator.

BDW = RDW + (DL – 28) × G = ?