How many PSI is 1 bar? How to convert bar to psi?
Bar and psi are both units of pressure. Bars are used in the metric system, and psi (pounds per square inch) are based on the avoirdupois system (that’s just a fancy way of referring to a system that uses pounds and ounces as units).
Converting bar to psi involves quite a lot of confusion because we have different conversions, namely bar to psi, bar to psig, bar to psia, bar to psid, and so on.
To avoid all the confusion, we simplified the bar to psi conversion by creating a ‘bar to psi conversion calculator’ and a table with calculated psi from bars of pressure. Here is how the calculator looks like (you will find it further on):
We will explain the differences between psi, psig, psia, and psid, and how do they relate to bars further on as well, but let’s go quickly over what all of these units of pressure mean before using the bar to psi converter.
Here is what different ‘pounds per square inch’ pressure units mean:
- psi stands for ‘Pounds per Square Inch’. This is the amount of pressure that a force of 1 pound of weight created on 1 square inch of surface. 1 bar is equal to 14.5037738 psi.
- psia stands for ‘pounds per square inch absolute‘. When converting to bars, psia is the same as psi; we add ‘a’ to indicate that this is a measure of absolute pressure relative to vacuum, not relative pressure to atmospheric pressure. 1 bar is equal to 14.5037738 psia.
- psig stands for ‘pounds per square inch gauge‘. When converting to bars, psig is the same as psi and psia; we add ‘g’ to indicate that this is a measure of relative pressure to atmospheric pressure. 1 bar is equal to 14.5037738 psig.
- psid stands for ‘pounds per square inch differential‘. When converting to bars, psid is the same as psi, psia, and psig. We use psid when we are measuring pressure relative to something else than atmospheric pressure.
The key outtake of all these units is this:
When converting to bars, all units (psi, psia, psig, psid) are quantitatively the same, and 14.5037738 of these units equal 1 bar.
Note: The conversion would be different if we were to convert all kinds of psi units to atmospheric pressure; in the case with bars, we’re not doing that. 1 bar is clearly defined as 100,000 Pascals or 100 kPA.
That means that when converting bars to psi, psia, psig, and psig, we will always get the same result.
It’s normal to be a bit confused by all these units of pressure. The simplest way to convert bars to psi, bars to psia, bars to psig, and bars to psig, is to just use this easy-to-use bars conversion calculator:
Bar To PSI Calculator (Same For psia, psig, And psid)
You simply input the number of bars you want to convert to psi, psia, psig, or psig, and the calculator will dynamically calculate the ‘pounds per square inch’ units of pressure. You can play around with numbers a bit as well:
Let’s illustrate with an example how to use this graph to convert bars into psi units of pressure.
Example: I have 2.3 bars of pressure in my car tires. How many psi is that?
You can use the bar calculator and you’ll get that 2.3 bars is equal to 33.36 psi. That also means that 2.3 bar is equal to:
- 33.36 psia.
- 33.36 psig.
- 33.36 psid.
Quantitatively, there is no difference between these units when are in relation to bars. As we have said earlier on, there would be a difference if these units were is relation to atmospheric pressure.
Let’s have a look at some calculated bar to psig values. We have summarized them in the table here:
Bar To psig Table
|Number Of Bars:||PSIG (Pounds Per Square In Gauge):|
|0.01 bar||0.0145 psig|
|0.1 bar||0.145 psig|
|1 bar||14.50 psig|
|2 bar||29.01 psig|
|2.3 bar||33.36 psig|
|3 bar||43.51 psig|
|4 bar||58.02 psig|
|5 bar||72.52 psig|
|10 bar||145.04 psig|
|20 bar||290.08 psig|
|30 bar||435.11 psig|
|40 bar||580.15 psig|
|50 bar||725.19 psig|
|60 bar||870.23 psig|
|70 bar||1,015.26 psig|
|80 bar||1,160.30 psig|
|90 bar||1,305.34 psig|
|100 bar||1,450.38 psig|
|200 bar||2,900.76 psig|
If you have a specific number of bars in mind and you would like to convert them to psi, you can use the calculator above.
Now, let’s have a more detailed look at what all these units of pressure mean:
Bar: Metric Unit Of Pressure
In the metric system, we use bars and Pascals (Pa) to measure pressure. Bar is defined as 100,000 Pa. To understand what that actually means, we have to look at what exactly Pascals are.
1 Pascal is defined as the force of 1 Newton (N) of pressure applied to 1 square meter of surface (m2). We usually label a Pascal as being equal to N/m2. 1 Bar is simply 100,000 N/m2.
That the numbers. What does a bar of pressure mean practically?
1 bar is an amount of pressure that’s a bit lower than atmospheric pressure at sea level. In fact, at sea level, you can measure that the pressure is about 1.013 bars.
If you were to take a hike to 111 meters above sea level, and the temperature would be 15°C, your barometer (a device that measures air pressure) would read about 1 bar.
Some fellow physicists might take offense if we were not to mention that Pascals are a SI unit, and bars are not a SI unit. That’s because a bar is only a substitute for 100,000 Pa that’s quite useful in practical applications such as measuring car tire pressure or even looking at refrigerant pressure-temperature charts (you can check an R410A PT chart here as an example).
You can read more about what a bar is here.
psi Or ‘Pounds Per Square Inch’ (lbf/in2)
To adequately convert bars to psi, we need to understand what psi actually is. Here’s the difference between bars and psi expressed in the simplest terms:
- 1 Bar is a force of 100,000 Newtons (N) applied to a 1 square meter (m2) surface.
- 1 psi is a force of 1 pound applied to a 1 square inch (in2) surface. That’s what we mean by psi or ‘pound-force per square inch’.
As you can see, none of the units here match. That’s why converting bars to psi is so difficult.
If you want to convert bars to psi, you have to first convert psi to Pascals (Pa). 1 psi is equal to 6895 Pa. You can read more about the differences between psi, psia, psig, and psid here.
Here is how you can convert bar to psi unit-by-unit:
How To Convert Bar To psi Step-By-Step
We know that 1 bar is equal to 100,000 Pa. We also know that 1 Pa is equal to 1 N/m2 and 1 psi is equal to 1 lb of force per square inch (lbf/in2).
For the bar to psi conversion, we need to first convert psi to Pa. Practically that means we need to convert lbf/in2 to N/m2. Here’s how we do that:
- Easy part (surface conversion): 1 m2 is equal to 1,550.031 in2. That means that 1 square inch is equal to 0.00064516 square meters.
- Hard part (force conversion): 1 N is defined as kg*m/s2. To convert pound-force, we need to know that 1 lb = 0.45359237 kg, and gravitational acceleration in pounds is expressed as 32.174049 ft/s2.
There are quite a few steps when converting 1 lbf to N. Here is a derivation from Wikipedia:
Basically, we need to know that 1 lbf is equal to 4.4482216152605 N. Let’s now convert lbf/in2 to N/m2:
lbf/in2 = 0.45359237 kg/ 0.00064516 m2 = 703.069579639 kg/m2
That means that 1 psi is equal to 703.069579639 Pa. We know that 1 bar is equal to 100,000 Pa. To calculate psi from 1 bar, we divide 100,000 Pa by 703.069579639 Pa.
That’s quite a complex derivation. If you have any questions regarding how to convert bars to psi, you can use the comments below and we’ll try to help you out.