mbar to psi Converter
Convert millibars to pounds per square inch. One millibar equals about 0.0145038 psi.
Result
The mbar to psi formula
The conversion factor comes from the definitions of the units: one bar is 100,000 pascals, one millibar is 100 pascals, and one psi is 6,894.757 pascals. Dividing 100 by 6,894.757 gives 0.0145038 psi per mbar.
psi = mbar x 0.0145037738
mbar = psi x 68.9475729Common mbar to psi values
Standard atmospheric pressure is 1,013.25 mbar, or 14.6959 psi. A 1,000 mbar reading is approximately 14.5038 psi. The difference between the two is the 13.25 mbar that takes standard atmosphere above a round 1,000 mbar.
| mbar | psi | kPa |
|---|---|---|
| 1 | 0.0145 | 0.1 |
| 10 | 0.1450 | 1.0 |
| 100 | 1.4504 | 10.0 |
| 500 | 7.2519 | 50.0 |
| 1,000 | 14.5038 | 100.0 |
| 1,013.25 | 14.6959 | 101.325 |
Gauge vs absolute pressure
A gauge pressure of 0 psi means the pressure equals the surrounding atmosphere. An absolute pressure of 0 psi means a perfect vacuum. Instruments label the reference, but the label is easy to miss. Before converting a reading for a tire, vacuum chamber or compressor, confirm which reference the gauge uses.
The unit conversion does not change the reference. If a gauge reports -0.5 bar gauge, converting it to psi still gives a negative gauge value. Convert the magnitude and keep the gauge/absolute label with the result.
Where mbar and psi are used
- Meteorology and weather stations report surface pressure in mbar or hPa.
- Vacuum systems often use mbar because the scale spans many orders of magnitude.
- Tire, hydraulic and pneumatic equipment in the US commonly uses psi.
- European and scientific equipment often uses bar, mbar or kPa.
- Always include the unit and reference in a converted result to avoid ambiguity.
Related Calculators
References
Frequently Asked Questions
How many psi is 1 mbar?
One millibar equals about 0.0145038 psi. To convert any mbar value to psi, multiply by 0.0145038. For example, 100 mbar is about 1.4504 psi, and 1,000 mbar is about 14.5038 psi.
Is mbar the same as hPa?
Yes, numerically. One millibar equals one hectopascal (1 mbar = 1 hPa). Weather reports often use hPa, while vacuum and pressure instruments often use mbar. The units are interchangeable for pressure values.
How do I convert psi back to mbar?
Divide the psi value by 0.0145038, or multiply by 68.9476. A 15 psi tire reading is about 1,034.2 mbar. Use the psi to mbar converter if you want the reverse direction without retyping the factor.
What is standard atmospheric pressure in mbar and psi?
Standard atmospheric pressure is 1,013.25 mbar, which equals 101.325 kPa, 1 atm, or about 14.6959 psi. Gauge pressure readings may be relative to atmosphere, so check whether the instrument reports absolute or gauge pressure.
Why is the psi result so much smaller than the mbar value?
A millibar is a much smaller pressure unit than a pound per square inch. It takes about 68.95 mbar to make one psi. The numerical value shrinks when you convert to psi, even though the physical pressure is unchanged.
Can I use this for vacuum readings?
Yes, as a unit conversion. Vacuum gauges often report mbar or Torr, and psi may appear on imperial equipment. Keep the sign convention consistent: a gauge pressure of -0.5 bar is not the same as an absolute pressure of 0.5 bar.