Bar to kPa:
multiply by 100

How many kPa are in a bar?

One bar is exactly 100 kPa. The bar is defined as 100,000 pascals, and a kilopascal is 1,000 pascals, so the conversion is a clean factor of 100 with no rounding.

Standard atmospheric pressure is 101.325 kPa, which is 1.01325 bar. That is why a bar is described as roughly one atmosphere, though it is slightly less.

Bar to kPa formula and worked example

Going the other way, a gauge reading of 250 kPa is 250 ÷ 100 = 2.5 bar. Slide the decimal point two places to the left.

Chart: bar to kilopascals

Where bar to kPa is used

Many car tyre gauges and pumps show bar, while manuals for some regions list kilopascals. A tyre set to 2.2 bar is 220 kPa, and a pressure of 2.5 bar is 250 kPa, so you can compare a pump with a door-jamb sticker in either unit.

Heating engineers meet the same pairs on boilers. A sealed central heating system often sits at about 1.5 bar when cold, which is 150 kPa. Compressors and water mains are quoted in bar, while engineering data sheets often switch to kPa.

More bar to kPa situations and a second worked example

Scuba divers and industrial gas users deal with much higher figures. A scuba cylinder filled to 200 bar holds gas at 200 × 100 = 20,000 kPa, and a cylinder at 232 bar is 23,200 kPa. Compressed air tools in a workshop, often set to around 6 bar, run at 600 kPa. The conversion is the same at every scale.

Here is a second worked example that shows the gauge versus absolute trap. A gauge reading of 2 bar means 2 bar above the surrounding air. At standard atmospheric pressure of 101.325 kPa, the absolute pressure is 200 + 101.325 = 301.325 kPa, or 3.01325 bar. Convert the gauge figure on its own and you get 200 kPa gauge, which is not the same as 200 kPa absolute.

A sanity check that works at any size: a bar is about 14.5 psi, and 100 kPa is the same pressure, so a figure in kPa should always look 100 times larger than the matching figure in bar. If a boiler gauge reads 1.5 bar and your sheet says 15 kPa, a decimal place has slipped.

Reading pressure labels in both units

Pressure ratings on equipment often mix units, so a quick mental conversion helps. A hose fitting rated at 10 bar is rated at 1,000 kPa, a tyre inflated to 2.2 bar sits at 220 kPa, and a pressure washer rated at 150 bar works at 15,000 kPa. The pressure is identical in each case; only the number on the label changes.

A sanity check: standard atmospheric pressure is 101.325 kPa, which is about 1.013 bar, so a figure near 100 kPa should correspond to roughly 1 bar. If your answer for an everyday pressure is far from that scale, the decimal point probably moved the wrong way.

Gauges usually show pressure above the surrounding air (gauge pressure), while some data sheets quote absolute pressure. The bar to kPa factor is the same for both, but the two figures differ by about 1 bar, or 101.325 kPa, so check which one a document means before comparing numbers.

Common mistakes when converting bar to kPa

• Confusing kPa with MPa. 1 MPa is 10 bar, so 1 bar is 0.1 MPa, not 1 kPa.
• Mixing bar with psi. A bar is about 14.5 psi, so never read a bar figure as psi.
• Treating gauge and absolute pressure as the same. Gauge pressure ignores the atmosphere, so check which one a spec uses before converting.
• Moving the decimal the wrong way. Bar to kPa makes the number bigger by 100.