Absolute Pressure vs. Gauge Pressure vs. Differential Pressure Calculator (Online Free)

Free Online Pressure Tool

Absolute druk versus manometerdruk versus differentiële druk

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.

PSIA and PSIG explained Differential pressure formula Engineering unit conversion Beginner-friendly examples
Absoluut
Referenced to vacuum
Typical unit label: PSIA
Graadmeter
Referenced to atmosphere
Typical unit label: PSIG
Differentieel
Point A minus Point B
Typical unit label: PSID

Calculator

Choose a calculation mode

Select one mode below. The calculator will update the labels, formula, and result explanation automatically.

Standard atmosphere reference: 101.325 kPa of 14.696 psi
Current formula
Absolute Pressure = Gauge Pressure + Atmospheric Pressure
Use this mode when you know gauge pressure and local atmospheric pressure.

Resultaat

Absolute druk

Live calculation
Select values and press Calculate
Input summary
Waiting for values.
Calculation steps
The step-by-step explanation will appear here.
Engineering note
Absolute pressure is referenced to a perfect vacuum. Gauge pressure is referenced to local atmosphere. Differential pressure compares two process points.
Absolute druk

Referenced to perfect vacuum

Absolute pressure starts at zero vacuum, so it is useful when atmospheric variation matters. Typical label: PSIA.

Buikdruk

Referenced to local atmosphere

Gauge pressure shows how much pressure is above or below the surrounding air. Typical label: PSIG.

Differentiële druk

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.

Druktype Referentiepunt Common Label Typical Uses
Absolute druk Perfect vacuum PSIA Vacuum systems, gas laws, altitude-sensitive measurement
Buikdruk Atmospheric pressure PSIG Compressors, hydraulics, pneumatics, everyday industrial measurement
Differentiële druk Another process point PSID Filters, flow measurement, tank level, room pressurization

Formulas

Core equations you should know

Absolute druk
Pabs = Pg + Patm
Buikdruk
Pg = Pabs – Patm
Differentiële druk
ΔP = P1 – P2

Examples

Quick practical examples

Gauge to Absolute: 50 psig + 14.696 psi = 64.696 psia
Absolute to Gauge: 80 kPa absolute – 101.325 kPa atmosphere = -21.325 kPa gauge
Differentiële druk: 120 kPa – 95 kPa = 25 kPa differential

Toepassingen

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.

Veelgestelde vragen

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.

Kan de overdruk negatief zijn?

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.

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