This converter turns inches of mercury into pounds per square inch instantly, using the exact factor 1 inch of mercury = 0.4911541996 pounds per square inch. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
US aviation and weather altimeter setting unit. The dominant US pressure unit for tyres, plumbing and compressors.
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
inches of mercury- The amount you are converting, measured in inches of mercury
0.4911541996- The exact number of pounds per square inch in one inch of mercury
pounds per square inch- The converted result
How it works, step by step
- Enter the number of inches of mercury you want to convert.
- The value is multiplied by 0.4911541996, the exact conversion factor.
- The result is displayed in pounds per square inch, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 inches of mercury
Multiply 5 by 0.4911542. That gives 2.4558 pounds per square inch. A quick sanity check: one inch of mercury is smaller than one pound per square inch, so the number should get smaller — and it does.
Converting 72 inches of mercury
72 × 0.4911542 = 35.3631 pounds per square inch. Working backwards, 35.3631 ÷ 0.4911542 returns 72 inches of mercury, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many pounds per square inch are in one inch of mercury?
Exactly 0.4911541996. 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 inches of mercury to pounds per square inch?
Pounds Per Square Inch = inches of mercury × 0.4911541996. To reverse it, divide instead: inches of mercury = pounds per square inch ÷ 0.4911541996, which is the same as multiplying by 2.036020461.
Is the inch of mercury bigger than the pound per square inch?
No. One inch of mercury is only 0.491154 of a pound per square inch, so the pound per square inch is the larger unit.
Why does my answer differ slightly from other inhg to psi 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 inch of mercury?
US aviation and weather altimeter setting unit.
What is a pound per square inch?
The dominant US pressure unit for tyres, plumbing and compressors.
Inches Of Mercury to pounds per square inch reference table
| Inches Of Mercury | Pounds Per Square Inch |
|---|---|
| 0.5 inHg | 0.245577 psi |
| 1 inHg | 0.491154 psi |
| 2 inHg | 0.982308 psi |
| 3 inHg | 1.4735 psi |
| 5 inHg | 2.4558 psi |
| 10 inHg | 4.9115 psi |
| 15 inHg | 7.3673 psi |
| 20 inHg | 9.8231 psi |
| 25 inHg | 12.2789 psi |
| 50 inHg | 24.5577 psi |
| 75 inHg | 36.8366 psi |
| 100 inHg | 49.1154 psi |
| 250 inHg | 122.7885 psi |
| 500 inHg | 245.5771 psi |
| 1000 inHg | 491.1542 psi |
Exact factor: 1 inch of mercury = 0.4911541996 pounds per square inch. Values rounded for display.