mmHg to Atmospheres
Convert mmhg to atmospheres instantly. 1 mmHg = 0.0013157897 atm. Includes the exact factor, a conversion table of common values and the definition of both units.
How to convert mmhg to atmospheres
To convert mmhg to atmospheres, divide by 759.9998917256 (multiply by 0.0013157897). The relationship is fixed, so the same factor works for any quantity — there is nothing to look up and nothing that changes with temperature, location or context.
atm = mmHg × 0.0013157897
mmHg to Atmospheres conversion table
The values people look up most often, rounded for reading. Use the calculator above for anything in between.
| mmHg | Atmospheres |
|---|---|
| 1 mmHg | 0.001316 atm |
| 2 mmHg | 0.002632 atm |
| 3 mmHg | 0.003947 atm |
| 5 mmHg | 0.006579 atm |
| 10 mmHg | 0.013158 atm |
| 20 mmHg | 0.026316 atm |
| 25 mmHg | 0.032895 atm |
| 50 mmHg | 0.065789 atm |
| 100 mmHg | 0.131579 atm |
| 500 mmHg | 0.657895 atm |
| 1,000 mmHg | 1.31579 atm |
What is a mmhg?
Millimetres of mercury, still the clinical unit for blood pressure.
What is a atmosphere?
The standard atmosphere, defined as exactly 101,325 Pa.
The formula
atm = mmHg × 0.0013157897
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the mmHg to Atmospheres
- Type the number of mmhg you want to convert.
- Read the result in atmospheres straight away — there is no button to press.
- Check the table below for the values that come up most often, or reverse the conversion with the linked atmospheres to mmhg page.
mmHg to Atmospheres — frequently asked questions
How many atmospheres are in a mmhg?
One mmhg equals 0.0013157897 atm. atm = mmHg × 0.0013157897
What is the formula to convert mmhg to atmospheres?
The formula is atm = mmHg × 0.0013157897. It is an exact definition rather than an approximation, so the conversion never drifts no matter how large the number.
How do I convert atmospheres back to mmhg?
Divide instead of multiplying: one atmosphere is 759.9998917256 mmHg. The reverse converter is linked in the related tools list.
Is this conversion exact?
Yes. Both units are defined against the same base unit by international agreement, so the factor is exact — any rounding you see is only in the display, which you can widen by entering more decimal places.
Is this mmhg to atmospheres free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
What people search for
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 19, 2026 · Calculation runs client-side · No data collected · Report an error