How many inHg is 1 mmHg?

1 millimeter of mercury (mmHg) equals approximately 0.039370 inches of mercury (inHg). This follows directly from the unit definitions: 1 inHg = 25.4 mmHg exactly (since 1 inch = 25.4 mm), so 1 mmHg = 1/25.4 ≈ 0.039370 inHg.

How do I convert mmHg to inHg manually?

Divide the mmHg value by 25.4. For example, 760 mmHg ÷ 25.4 = 29.921 inHg (standard atmosphere). To convert inHg back to mmHg, multiply by 25.4.

What is standard atmospheric pressure in mmHg and inHg?

Standard atmospheric pressure is 760 mmHg (also called 760 Torr at 0 °C), which equals approximately 29.921 inHg. US weather and aviation services commonly report 29.92 inHg as the standard reference.

Is mmHg the same as Torr?

For practical purposes, 1 mmHg ≈ 1 Torr. Strictly, 1 Torr = 1/760 of a standard atmosphere = 133.322 Pa, while 1 mmHg is defined by the density of mercury at 0 °C = 133.3224 Pa — a difference of less than 0.0002%, negligible for most applications.

Why do weather reports use inHg instead of mmHg?

The United States uses inHg for aviation altimeter settings and domestic weather broadcasts, a legacy of the pre-metric measurement system. Most other countries and scientific contexts prefer hectopascals (hPa) or millibars. mmHg is still common in medical blood pressure readings worldwide.

What is 29.92 inHg in mmHg?

29.92 inHg × 25.4 = 759.97 mmHg, which is essentially standard atmospheric pressure (760 mmHg). US weather services often cite 29.92 inHg as the standard sea-level reference for pressure altitude calculations.

mmHg to inHg Converter

Name: mmHg to inHg Converter
Availability: InStock
Author: Nham Vu

Enter a pressure in mmHg and get the inHg equivalent instantly, with reverse inHg-to-mmHg conversion and a reference table.

Converter

Pressure in millimeters of mercury (mmHg)

Result in inches of mercury (inHg)

Reverse: inHg to mmHg

Pressure in inHg

Result in mmHg

Reference Table

mmHg inHg

100 mmHg 3.9370

200 mmHg 7.8740

300 mmHg 11.811

400 mmHg 15.748

500 mmHg 19.685

600 mmHg 23.622

700 mmHg 27.559

760 mmHg 29.921

800 mmHg 31.496

900 mmHg 35.433

1000 mmHg 39.370

1500 mmHg 59.055

Summary

Enter a pressure in mmHg and get the inHg equivalent instantly, with reverse inHg-to-mmHg conversion and a reference table.

How it works

Enter the pressure value in millimeters of mercury (mmHg) in the top input.
The inHg result appears instantly without pressing any button.
Use the reverse field to convert inHg back to mmHg.
Click "Copy" next to any result to copy the value to your clipboard.
Check the reference table for common mmHg-to-inHg conversions at a glance.

Use cases

Convert blood pressure readings from mmHg to inHg for US weather station comparisons.
Translate barometric pressure from mmHg (used in some European instruments) to inHg for US weather reports.
Convert vacuum gauge readings between mmHg and inHg in industrial applications.
Cross-check altimeter settings when switching between metric and US aviation pressure units.
Verify pressure thresholds in HVAC or pneumatic systems that mix mmHg and inHg specs.
Quickly look up standard sea-level pressure equivalences for meteorology calculations.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu