# How do I convert PSI to PSIA and PSIG?

**URL:** <https://forumautomation.com/t/how-do-i-convert-psi-to-psia-and-psig/12255>\
**Category:** Pressure Measurement\
**Tags:** interviewquestions, instrumentation\
**Created:** [July 5, 2024, 1:59pm UTC](https://forumautomation.com/t/how-do-i-convert-psi-to-psia-and-psig/12255 "2024-07-05T13:59:34Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![automation\_engineer6](https://forumautomation.com/user_avatar/forumautomation.com/automation_engineer6/32/7656_2.png) [@automation\_engineer6](https://forumautomation.com/u/automation_engineer6)\
**Post date:** [July 5, 2024, 1:59pm UTC](https://forumautomation.com/t/how-do-i-convert-psi-to-psia-and-psig/12255/1 "2024-07-05T13:59:34Z")

</div>

How do I convert PSI to PSIA and PSIG? ![image](https://cdn.forumautomation.com/original/2X/6/6dbc2f05bf608f0cbb794b8b1f8f85a7940586b5.png)

---

<div class="post-metadata">

**Author:** ![Instrument\_Engineer](https://forumautomation.com/user_avatar/forumautomation.com/instrument_engineer/32/6734_2.png) [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\
**Post date:** [July 10, 2024, 7:53am UTC](https://forumautomation.com/t/how-do-i-convert-psi-to-psia-and-psig/12255/2 "2024-07-10T07:53:51Z")

</div>

Converting PSI to PSIA and PSIG is straightforward once you understand the relationship between them.

**How to Convert PSI to PSIA and PSIG**

Pressure measurements can sometimes be confusing because there are different units used to describe them, such as PSI, PSIA, and PSIG. Here’s a quick guide to help you convert between these units.

**1. PSI (Pounds per Square Inch):** This is the standard unit of pressure. However, PSI alone doesn’t specify if it’s relative to atmospheric pressure or absolute pressure.

**2. PSIA (Pounds per Square Inch Absolute):** This measures pressure relative to a perfect vacuum (0 PSIA). It includes atmospheric pressure in its measurement. At sea level, atmospheric pressure is about 14.7 PSI.

**3. PSIG (Pounds per Square Inch Gauge):** This measures pressure relative to atmospheric pressure. At sea level, 0 PSIG equals 14.7 PSIA. **Conversions:**

 ![image](https://cdn.forumautomation.com/original/2X/2/2c2df03597a80a1feee7373841f9ae53067e2e1f.png)

**Key Takeaway:**

- **PSIA** includes atmospheric pressure in its measurement.
- **PSIG** excludes atmospheric pressure and measures just the pressure exerted by the substance in question.

I hope this clears things up! Feel free to ask if you have more questions.