Pressione assoluta rispetto a pressione relativa rispetto a pressione differenziale
Use this free calculator to convert between absolute pressure and gauge pressure, or calculate differential pressure between two process points. It supports common engineering units such as Pa, kPa, MPa, bar, and psi.
Calculator
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Select one mode below. The calculator will update the labels, formula, and result explanation automatically.
Risultato
Pressione assoluta
Referenced to perfect vacuum
Absolute pressure starts at zero vacuum, so it is useful when atmospheric variation matters. Typical label: PSIA.
Referenced to local atmosphere
Gauge pressure shows how much pressure is above or below the surrounding air. Typical label: PSIG.
Referenced to another process point
Differential pressure is the difference between two measured points. Typical label: PSID.
Comparison
Absolute vs. Gauge vs. Differential Pressure
The difference is the reference point. That reference determines how the pressure is measured, displayed, and used in real systems.
| Tipo di pressione | Punto di riferimento | Common Label | Typical Uses |
|---|---|---|---|
| Pressione assoluta | Perfect vacuum | PSIA | Vacuum systems, gas laws, altitude-sensitive measurement |
| Pressione di calibro | Atmospheric pressure | PSIG | Compressors, hydraulics, pneumatics, everyday industrial measurement |
| Pressione differenziale | Another process point | PSID | Filters, flow measurement, tank level, room pressurization |
Formulas
Core equations you should know
Esempi
Quick practical examples
Applicazioni
When to use each pressure type
Use absolute pressure when
You need a true pressure value relative to vacuum, especially in vacuum equipment, gas calculations, and high-accuracy process work.
Use gauge pressure when
You want to know pressure relative to surrounding air, such as in air compressors, pumps, hydraulic systems, and most routine plant measurements.
Use differential pressure when
You need to compare pressure between two points, such as across a filter, orifice, heat exchanger, clean room, or sealed tank system.
Related Guides
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FAQ
Frequently asked questions
What is the difference between absolute pressure and gauge pressure?
Absolute pressure is measured from perfect vacuum. Gauge pressure is measured from the surrounding atmospheric pressure.
La pressione relativa può essere negativa?
Yes. If the measured pressure is below atmospheric pressure, the gauge pressure is negative.
What does differential pressure mean?
Differential pressure is the pressure difference between two points. It is often used for filter monitoring, flow measurement, and level measurement in closed tanks.
Why is atmospheric pressure important in pressure conversion?
Because gauge pressure uses atmosphere as the reference. To convert correctly between gauge and absolute pressure, you need atmospheric pressure.
What are PSIA, PSIG, and PSID?
PSIA means pounds per square inch absolute. PSIG means pounds per square inch gauge. PSID means pounds per square inch differential.