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Bar to Kilopascals Converter
↔ Convert kPa to bar instead

Common Conversions

bar kPa
0.01 1
0.05 5
0.1 10
0.25 25
0.5 50
1 100
1.01325 101.325
2 200
5 500
10 1000
50 5000
100 10000

Why this conversion matters in chemistry

Bar and kPa are the two units you'll see most often in modern thermodynamic tables, and moving between them is as clean as pressure conversions get. 1 bar is exactly 100 kPa by definition, so the arithmetic is just shifting a decimal two places. A supercritical CO₂ process held just above the critical point at 74 bar is 7400 kPa; a rotary evaporator pulling half an atmosphere of vacuum at 0.5 bar is 50 kPa. The equivalence is why IUPAC standardized on 1 bar as the thermodynamic reference pressure in 1982 — it plays nicely with SI while keeping numbers in a range that reads well without scientific notation.

Formula

kPa = bar × 100

Worked Examples

1 bar = 100 kPa

The defining equivalence. Modern IUPAC standard pressure, and the anchor for most post-1982 thermodynamic tables.

1.01325 bar = 101.325 kPa

One standard atmosphere. Slightly above 1 bar — the difference that keeps older reference tables from quite lining up with new ones.

0.5 bar = 50 kPa

Reduced pressure for vacuum distillation of thermally sensitive compounds — enough below atmospheric to drop boiling points without pulling a deep vacuum.

10 bar = 1000 kPa

Elevated pressure for a catalytic reactor — the kind of working pressure a benchtop hydrogenation or autoclave might hold.

Frequently Asked Questions

How do I convert bar to kPa?
Multiply by 100. The conversion is exact — 1 bar is 100 kPa by definition, so 5 bar is 500 kPa with no rounding needed. One of the few conversions where you never have to worry about precision.
Why is the conversion so clean?
The bar was defined as exactly 100,000 Pa (100 kPa). That was a deliberate choice — the unit exists specifically because kPa values in atmospheric-pressure range are cleaner to work with than Pa. IUPAC chose 1 bar as standard pressure partly for this reason.
Should I use bar or kPa in chemistry?
Both are acceptable. R = 8.314 J/(mol·K) is numerically equal to 8.314 kPa·L/(mol·K), so kPa drops into gas-law calculations directly. If your pressure is in bar, multiply by 100 to get kPa, then use that form of R.
What's the difference between bar and pascal?
1 bar is 100,000 Pa, or 100 kPa. The pascal is the SI unit of pressure (1 Pa = 1 N/m²). Bar isn't strictly SI but is accepted for use alongside it. In chemistry, kPa is almost always more practical than Pa — most lab pressures land in the tens to hundreds of kPa, which reads cleaner than 10⁴ to 10⁵ Pa.