Mistake guide
Confusing mmHg and hPa
A weather report of 1013 hPa and a blood pressure reading of 120 mmHg are comparable figures.
A weather report of 1013 hPa and a blood pressure reading of 120 mmHg are comparable figures.
Both figures are pressure readings but in different units. 1 mmHg = 133.322387415 Pa, about 1.333 hPa. 120 mmHg equals about 160 hPa — the same numeric range but a different pressure.
The mercury column was historically the standard pressure unit in medicine and meteorology. Meteorology switched to hectopascal while medicine kept mmHg — and the numbers happen to sit in similar ranges.
Always read the stated unit instead of inferring the quantity from the number. The conversion factor from mmHg to hPa is about 1.3332. Medical values belong with the treating professional; UnitCloud only provides the unit arithmetic.
Matching conversions
Unit family: Pressure
Sources
Do not use as the sole basis for official, medical, safety-critical or contractual decisions.
Citation note: UnitCloud, mistake guide, sources reviewed: September 2026. Source basis: BIPM SI Brochure · NIST Guide to SI Appendix B.