This converter turns millimeters of mercury into inches of mercury instantly, using the exact factor 1 millimeter of mercury = 0.03937007456 inches of mercury. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
The clinical unit for blood pressure worldwide. US aviation and weather altimeter setting unit.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
millimeters of mercury- The amount you are converting, measured in millimeters of mercury
0.03937007456- The exact number of inches of mercury in one millimeter of mercury
inches of mercury- The converted result
How it works, step by step
- Enter the number of millimeters of mercury you want to convert.
- The value is multiplied by 0.03937007456, the exact conversion factor.
- The result is displayed in inches of mercury, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 millimeters of mercury
Multiply 5 by 0.039370075. That gives 0.19685 inches of mercury. A quick sanity check: one millimeter of mercury is smaller than one inch of mercury, so the number should get smaller — and it does.
Converting 72 millimeters of mercury
72 × 0.039370075 = 2.8346 inches of mercury. Working backwards, 2.8346 ÷ 0.039370075 returns 72 millimeters of mercury, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many inches of mercury are in one millimeter of mercury?
Exactly 0.03937007456. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert millimeters of mercury to inches of mercury?
Inches Of Mercury = millimeters of mercury × 0.03937007456. To reverse it, divide instead: millimeters of mercury = inches of mercury ÷ 0.03937007456, which is the same as multiplying by 25.4000027.
Is the millimeter of mercury bigger than the inch of mercury?
No. One millimeter of mercury is only 0.0393701 of a inch of mercury, so the inch of mercury is the larger unit.
Why does my answer differ slightly from other mmhg to inhg converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a millimeter of mercury?
The clinical unit for blood pressure worldwide.
What is a inch of mercury?
US aviation and weather altimeter setting unit.
Millimeters Of Mercury to inches of mercury reference table
| Millimeters Of Mercury | Inches Of Mercury |
|---|---|
| 0.5 mmHg | 0.019685 inHg |
| 1 mmHg | 0.03937 inHg |
| 2 mmHg | 0.07874 inHg |
| 3 mmHg | 0.11811 inHg |
| 5 mmHg | 0.19685 inHg |
| 10 mmHg | 0.393701 inHg |
| 15 mmHg | 0.590551 inHg |
| 20 mmHg | 0.787401 inHg |
| 25 mmHg | 0.984252 inHg |
| 50 mmHg | 1.9685 inHg |
| 75 mmHg | 2.9528 inHg |
| 100 mmHg | 3.937 inHg |
| 250 mmHg | 9.8425 inHg |
| 500 mmHg | 19.685 inHg |
| 1000 mmHg | 39.3701 inHg |
Exact factor: 1 millimeter of mercury = 0.03937007456 inches of mercury. Values rounded for display.