Pa SI derived
Measures: Pressure — how concentrated a push
Pascal
One newton spread over one square metre — a very gentle press.
PressureHow it's defined
Defined as N/m². It is tiny — a sheet of paper resting on a table presses down at about one pascal — so weather maps use hectopascals and engineers use kilopascals.
1 Pa = 1 N/m² — exact1 hPa = 100 Pa — exact (the weather-map unit)
Convert — honestly
Pa equals
0.00001 bar
Bar · factor exact — exact by definition
0.000145037738 psi
Pound per square inch · factor exact — exact (derived from lb, in, g₀)
Conversions run through the pascal using the stated factors — no rounding beyond display precision, and every factor says whether it's exact or measured.
Where you meet it
- Pressurii-to-be — its base unit
- Weather reports (1013 hPa is a normal day)
Other ways to measure pressure
Source
This page is an authored summary of the authoritative definition — checkable one click away.
BIPM — The International System of Units (SI Brochure, 9th ed.)