Calculate a starting length of pull for a shotgun or rifle from your elbow-to-trigger-finger measurement, compare it with a stock’s LOP, or convert units.

Measure elbow crease to first finger pad with a consistent method; actual fit depends on the firearm and posture.

Reference mode: inside of the bent elbow to the pad of your trigger finger. Convert mode: the stock’s length of pull.

Optional settings
Blank means zero. Use a negative value to shorten for bulky clothing.

Blank means zero. Supply your own signed adjustment.

Length of Pull Formula

Reference mode adds your supplied elbow-crease-to-first-finger-pad measurement and two explicit signed offsets. This body measurement is only a rough starting reference, not a validated formula for an individual’s required stock length:

LOPreference = E + C + F
  • LOPreference is the arithmetic reference length, expressed in the selected unit
  • E is the elbow-to-finger measurement; C is your signed clothing allowance; F is your signed fit offset. Both optional offsets default to zero when blank.

Use consistent units before adding the values. Clothing allowance and fit offset are user-supplied assumptions; the calculator does not automatically subtract a fixed amount for medium or heavy clothing. Comparison mode reports target minus current length, with the sign showing which number is larger. Conversion mode uses 1 in = 2.54 cm = 25.4 mm. A nearest-one-eighth-inch value in Calculation details is numerical rounding only, not a modification dimension or fit recommendation.

What is a Length of Pull?

Definition:

For a firearm stock, length of pull is the distance from the trigger face to the center of the rear recoil pad or buttplate. Savage Arms defines it from the recoil-pad center to the trigger face; SIG Sauer also defines the trigger-to-stock measurement. It is distinct from bow draw length and from an elbow-to-finger body measurement. The result does not diagnose fit, assign a universal size category or provide stock-cutting or modification instructions.

How to Calculate Length of Pull?

Example Problem:

The following example illustrates reference arithmetic using a chosen offset; the offset is not a general clothing recommendation.

Suppose the supplied elbow-to-finger measurement is 14.25 inches, the user chooses a −0.25-inch clothing allowance, and the additional fit offset is zero.

Add the supplied values using the reference formula:

LOPreference = E + C + F

LOPreference = 14.25 + (−0.25) + 0

LOPreference = 14 inches = 35.56 cm = 355.6 mm. This is the result of the stated inputs, not a prescribed stock length or a validated fit assessment.