Gauges read zero at ambient air pressure (gauge pressure, psig), but gas laws and many specifications need absolute pressure (psia), measured from a perfect vacuum.
How to use the PSIG to PSIA Converter
- Gauge pressure
- Atmospheric pressure
- Every result field is editable: type into Absolute pressure and Gauge pressure plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
The atmospheric pressure is added to the gauge reading. Type an absolute pressure into the result to get the gauge reading.
Inputs explained
| Field | What to enter |
|---|---|
| Gauge pressure | In psig |
| Atmospheric pressure | Units: psi, kPa, hPa, bar, inHg |
Example values
How the main result changes when Gauge pressure changes and everything else stays at the example values above:
| Gauge pressure (psig) | Absolute pressure (psi) |
|---|---|
| 15 | 29.6959 |
| 22.5 | 37.1959 |
| 30 | 44.6959 |
| 37.5 | 52.1959 |
| 45 | 59.6959 |
| 60 | 74.6959 |
Formula
psia = psig + atmospheric pressure (14.696 psi at sea level)Worked example
Inputs — Gauge pressure: 30 psig; Atmospheric pressure: 14.6959 psi.
Results — Absolute pressure = 44.6959 psi.
Frequently asked questions
What is 0 psig in psia?
14.696 psia at sea level.
Can absolute pressure be negative?
No; 0 psia is a perfect vacuum.
What formula does the PSIG to PSIA Converter use?
psia = psig + atmospheric pressure (14.696 psi at sea level).