PSIG to PSIA Converter
PSIG (pounds per square inch gauge) measures pressure relative to local atmospheric pressure. A gauge reads 0 PSIG at atmospheric pressure. PSIA (pounds per square inch absolute)...
Formula
Source: Engineering Toolbox | Last reviewed: June 7, 2026
Examples
0 psig
= 14.7 psia
- P_atm_psi = 14.696
Atmospheric pressure at sea level
100 psig
= 114.7 psia
- P_atm_psi = 14.696
-14.696 psig
= 0 psia
- P_atm_psi = 14.696
Perfect vacuum (absolute zero pressure)
Quick Reference Table
| PSIG | PSIA |
|---|---|
| 0 | 14.7 |
| 10 | 24.7 |
| 50 | 64.7 |
| 100 | 114.7 |
| 200 | 214.7 |
| 500 | 514.7 |
Where is this used?
Frequently Asked Questions
Why do I need absolute pressure?
Many engineering calculations (gas laws, thermodynamic properties, compressor performance) require absolute pressure. Using gauge pressure in these equations gives incorrect results.
How does elevation affect this conversion?
At higher elevations, atmospheric pressure is lower. At 5000 ft, P_atm ≈ 12.2 psia. The converter's P_atm_psi condition lets you adjust for your elevation.
What is the difference between PSIG and PSIV?
PSIG (gauge) reads positive above atmospheric. PSIV (vacuum) measures below atmospheric. A vacuum of 10 PSIV equals psig = -10. To convert, psig = -PSIV.
Reviewed for accuracy
· Last reviewed: June 7, 2026
All calculations are for reference only. Always verify with manufacturer data and a qualified engineer for critical applications. Learn about our editorial process.