PSI to Bar Converter

PSI to Bar

Convert psi (psi) to bar (bar). Both measure force per area, and the conversion comes up in weather, automotive, diving work.

The Formula

`` bar = psi × 0.0689475729317 psi = bar × 14.503773773 `

One psi is 0.068948 bar, and one bar is 14.5038 psi.

Conversion Table

PSI	Bar
1 psi	0.068948 bar
2 psi	0.137895 bar
5 psi	0.344738 bar
10 psi	0.689476 bar
25 psi	1.7237 bar
50 psi	3.4474 bar
100 psi	6.8948 bar
500 psi	34.4738 bar
1,000 psi	68.9476 bar

The Other Direction

Bar	PSI
1 bar	14.5038 psi
2 bar	29.0075 psi
5 bar	72.5189 psi
10 bar	145.0377 psi
25 bar	362.5943 psi
50 bar	725.1887 psi
100 bar	1,450.38 psi
500 bar	7,251.89 psi
1,000 bar	14,503.77 psi

What Each Unit Is

PSI (psi) — pounds-force per square inch, equal to 6,894.76 pascals. The imperial pressure unit, still standard for US tyres, plumbing and compressed air.

Bar (bar) — exactly 100,000 pascals — close to, but not exactly, one atmosphere. Introduced by meteorologist Vilhelm Bjerknes; weather maps use millibars.

A Sense of Scale

• Car tyres run at 32–35 psi
• Household water is 40–60 psi
• Sea-level pressure is about 1.013 bar
• Diving adds 1 bar per 10 m of depth

Precision

The factor 0.0689475729317 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const psiToBar = (value) => value * 0.0689475729317; ``

Where This Conversion Comes Up

• Weather
• Automotive
• Diving
• Aviation
• HVAC

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 psi with the factor truncated at each decimal place:

Decimals kept	Factor	137 psi becomes	Error
0	0	0	100.0000%
1	0.1	13.7	45.0377%
2	0.07	9.59	1.5264%
3	0.069	9.453	0.0760%
4	0.0689	9.4393	0.0690%

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured psi to three significant figures, the answer in bar is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From PSI

The same value in every other unit this converter supports for pressure:

From	To	Unit
1 psi	6,894.76 Pa	Pascals
1 psi	6.89476 kPa	Kilopascals
1 psi	0.068046 atm	Atmospheres
1 psi	51.7149 mmHg	mmHg

Chaining conversions works — psi to metres to feet gives the same answer as psi to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.