In the hydro-static pressure formula, if you use an oil field unit, you must see the hydro-static formula like this

**Pressure, psi = 0.052 x Mud Weight (ppg) x TVD (ft)**

I got the question asking about how the constant** 0.052** is figured out.

**What is 0.052?**

0.052 is a constant used for converting ppg-ft into pound per square inch (lb/in^{2})

Do you know how it comes from? Let’s get started

First of all, the unit conversions that you need to know are as follows:

1 gallon = 231 cubic inch (inch^{3})

1 ft = 12 inch

Convert density from ppg (pound per gallon) to lb per cubic inch

Basic hydrostatic pressure

The constant can be determined by substituting the unit conversion.

The constant is 0.051948 and if we round it up, it will be **0.052**.