Adjusting lbf (pounds force) weights for gravity at the point of use

Adjusting lbf (pounds force) Weights for Gravity at Point of Use

When weights are used to perform force calibrations they should be corrected for the gravity and air buoyancy at the point of use.

Where the values of the weights are given in true mass the force in lbf is determined using the following formula:

When manufacturing and adjusting force weights in lbf it is desirable to adjust them to a nominal force value.  To determine the true mass value required to apply a given force use the following formula:


mT = true mass of the weight

g = local acceleration due to gravity

d = local air density (usually around 0.0012 Mg/m3)

D = density of the weight in the same units as d

Lastly, sometimes force weights adjusted in lbf for a specific gravity to be used at another location with a different gravity but the same air density.  This requires a correction factor be calculated as follows:

Force weights adjusted for use at gravity value:  980665 mgals

To be used at the location with gravity value:  979563.577  mgals

Additional notes:

This value used only if working in pounds-force; highly recommend performing all calculations in SI units and true mass with conversion to other unit systems at the end if needed

All parties must understand what this means and why conventional is being used (the old vernacular used apparent mass versus brass in normal air with a density of 8.4 for the brass, same air density as shown)

Tate (NIST. Technician) used this method 50 years ago; again, the use of 9.80665 indicates pounds-force which means the true mass is in pounds

It works, however, note that no air buoyancy correction is shown. If air buoyancy is to be considered, might be best to use the original equation and plug in the required new values for local gravitational acceleration and local air buoyancy

Two other blogs related to this topic can be found here:

  1. How to Convert Force to Mass
  2. Force Applications for Mass Reference Standard

Everything we do, we believe in changing how people think about force and torque calibration.  Morehouse believes in thinking differently about force and torque calibration and equipment.  We challenge the "just calibrate it" mentality by educating our customers on what matters, what causes significant errors, and focus on reducing them.  Morehouse makes our products simple to use and user-friendly.  And we happen to make great force equipment and provide unparalleled calibration services.

Wanna do business with a company that focuses on what matters most?  Email us at

Please share if you found this helpful.

Newsletter Subscription

Find Related Articles

When You're Looking for More Accurate Measurements

Morehouse would like the opportunity to earn your business. Contact us today.
Contact Us
  • Type

Top cross linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram