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

### lbf calculator - Adjusting lbf (pounds-force) Weights for Gravity at the Point of Use

Morehouse lbf calculator or force to mass.  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:

Where:

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 are 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 to 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

This value is 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, the 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

Morehouse has an easy spreadsheet tool to help convert force to mass that can be found here.

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

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 and what causes significant errors and focus on reducing them.

Morehouse makes our products simple to use and user-friendly. We also happen to make great force equipment and provide unparalleled calibration services.

Do you want to do business with a company that focuses on what matters most?  Email us at info@mhforce.com.

• We're committed to your privacy. Morehouse Instrument Company uses the information you provide to us to contact you about our relevant content, products, and services. You may unsubscribe from these communications at any time. For more information, check out our Privacy Policy.