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Inches of Mercury to Kilopascal Converter
↔ Convert kPa to inHg instead

Common Conversions

inHg kPa
0.1 0.339
0.5 1.693
1 3.386
2 6.773
5 16.932
10 33.864
15 50.796
20 67.728
25 84.66
29.921 101.325
50 169.32
100 338.639

Why this conversion matters in chemistry

US barometric pressure runs in inches of mercury — sea-level standard is 29.92 inHg, equivalent to 101.325 kPa. International METAR weather data and SI-aligned chemistry calculations use kPa or hPa. The factor is 3.38639 kPa per inHg, exact through the SI definitions of both. The conversion comes up at any boundary between US barometric data and an SI-aligned calculation — a barometric correction to a boiling-point measurement, a pressure-sensor calibration against local atmospheric data, or any vapor-pressure work that crosses unit conventions.

Formula

kPa = inHg × 3.38639

Worked Examples

29.921 inHg = 101.325 kPa

Standard atmospheric pressure expressed in both unit systems.

1 inHg = 3.386 kPa

The factor itself — useful as a quick mental check on a barometric reading.

10 inHg = 33.864 kPa

A low-pressure measurement — about a third of an atmosphere, the kind of reduced pressure a vacuum operation might hold.

15 inHg = 50.796 kPa

About half an atmosphere — the working range of vacuum distillation for moderately volatile solvents.

Frequently Asked Questions

How do I convert inHg to kPa?
Multiply by 3.38639. So 29.921 inHg becomes 101.325 kPa — the standard atmospheric pressure expressed in both unit systems.
Is kPa preferred in chemistry?
Yes. Kilopascals are SI-derived and the standard for scientific publications worldwide. Inches of mercury survives mainly in US meteorology, aviation, and some industrial contexts.
What kPa values are common in chemistry?
101.325 kPa for one standard atmosphere; 100 kPa for the IUPAC standard pressure of 1 bar. Routine lab chemistry sits between roughly 1 and 200 kPa, depending on whether vacuum or pressurization is involved.