The inch of mercury
The inch of mercury (inHg) equals 3,386.389 Pa under the NIST SP 811 conventional definition. It is the standard unit for barometric pressure on US weather reports and for altimeter settings in US aviation.
Inches of mercury to Millibars Converter
1 inHg = 33.8639 mbar (inch of mercury → millibar)
1 inHg = 33.8639 mbar
1 inch of mercury equals 33.8639 millibars. To convert inches of mercury to millibars, multiply the inch of mercury value by 33.8639. For quick reference: 1 inHg = 33.8639 mbar, 5 inHg = 169.319 mbar, 10 inHg = 338.639 mbar, 100 inHg = 3386.39 mbar.
Formula
Millibars = Inches of mercury × 33.8639Quick
How to convert inches of mercury to millibars
Take your value
Start with your value in inches of mercury.
Multiply by 33.8639
Multiply the inch of mercury value by 33.8639. This is the exact conversion factor from inches of mercury to millibars.
Read the result
The product is your value in millibars. For example, 5 inHg × 33.8639 = 169.319 mbar.
Conversion formula
The exact factor from inches of mercury to millibars is 33.8639.
Millibars = Inches of mercury × 33.8639
Inches of mercury to Millibars conversion table
Fifty common reference values, hand-picked for skim utility. Use the calculator above for any value not listed.
| Inches of mercury (inHg) | Millibars (mbar) |
|---|---|
| 0.001 inHg | 0.033864 mbar |
| 0.01 inHg | 0.33864 mbar |
| 0.1 inHg | 3.3864 mbar |
| 0.5 inHg | 16.932 mbar |
| 1 inHg | 33.864 mbar |
| 1.5 inHg | 50.796 mbar |
| 2 inHg | 67.728 mbar |
| 2.5 inHg | 84.66 mbar |
| 3 inHg | 101.59 mbar |
| 4 inHg | 135.46 mbar |
| 5 inHg | 169.32 mbar |
| 6 inHg | 203.18 mbar |
| 7 inHg | 237.05 mbar |
| 8 inHg | 270.91 mbar |
| 9 inHg | 304.78 mbar |
| 10 inHg | 338.64 mbar |
| 14 inHg | 474.09 mbar |
| 15 inHg | 507.96 mbar |
| 20 inHg | 677.28 mbar |
| 25 inHg | 846.6 mbar |
| 30 inHg | 1015.9 mbar |
| 32 inHg | 1083.6 mbar |
| 35 inHg | 1185.2 mbar |
| 40 inHg | 1354.6 mbar |
| 50 inHg | 1693.2 mbar |
| 60 inHg | 2031.8 mbar |
| 75 inHg | 2539.8 mbar |
| 80 inHg | 2709.1 mbar |
| 100 inHg | 3386.4 mbar |
| 101.325 inHg | 3431.3 mbar |
| 150 inHg | 5079.6 mbar |
| 200 inHg | 6772.8 mbar |
| 250 inHg | 8466 mbar |
| 300 inHg | 10159 mbar |
| 400 inHg | 13546 mbar |
| 500 inHg | 16932 mbar |
| 760 inHg | 25737 mbar |
| 1000 inHg | 33864 mbar |
| 1013.25 inHg | 34313 mbar |
| 2000 inHg | 67728 mbar |
| 5000 inHg | 169319 mbar |
| 10000 inHg | 338639 mbar |
| 14.7 inHg | 497.8 mbar |
| 50000 inHg | 1693195 mbar |
| 100000 inHg | 3386389 mbar |
| 101325 inHg | 3431259 mbar |
| 200000 inHg | 6772778 mbar |
| 500000 inHg | 16931945 mbar |
| 1000000 inHg | 33863890 mbar |
| 10000000 inHg | 338638900 mbar |
Real-world reference
Standard atmospheric pressure is 29.92 inHg. US weather reports typically quote barometric pressure in inHg. In millibars, that gives you: 1 inHg = 33.8639 mbar, 10 inHg = 338.639 mbar, 100 inHg = 3386.39 mbar.
Frequently asked questions
- How many millibars are in 1 inch of mercury?
- 1 inch of mercury equals 33.8639 millibars.
- How do I convert inches of mercury to millibars?
- Multiply the inch of mercury value by 33.8639. So x inHg × 33.8639 = the equivalent in mbar.
- What is 5 inches of mercury in millibars?
- 5 inches of mercury equals 169.319 millibars.
- What is 10 inches of mercury in millibars?
- 10 inches of mercury equals 338.639 millibars.
- What is 100 inches of mercury in millibars?
- 100 inches of mercury equals 3386.39 millibars.
- How do I convert back from millibars to inches of mercury?
- Multiply the millibar value by 0.02953. For example, 1 mbar = 0.02953 inHg.
- Is the inch of mercury bigger than the millibar?
- Yes. 1 inch of mercury is larger than 1 millibar — specifically 33.8639 times larger.
- Are these conversion factors exact?
- The factor is derived directly from the SI definitions of inch of mercury and millibar; the displayed value is rounded for readability, and the browser computes using IEEE 754 double-precision arithmetic.
About the inch of mercury and the millibar
The millibar
The millibar (mbar) equals exactly 100 Pa — identical to the hectopascal (hPa) used in modern meteorology. Weather maps almost universally use mbar/hPa for sea-level pressure isobars.