kPa to Atm Converter
One standard atmosphere is defined as exactly 101,325 pascals, which is exactly 101.325 kilopascals, so kilopascals to atmospheres is a single division: atm = kPa / 101.325. That makes 1 kPa 0.00986923266716 atm, 10 kPa 0.0986923266716 atm, 100 kPa 0.986923266716 atm, 101.325 kPa exactly 1 atm and 1,000 kPa 9.86923266716 atm. The figure worth a second look is 100 kPa, because it is exactly one bar and not one atmosphere: it falls about 1.3 percent short, which is the whole reason these two units get mixed up. This page opens the converter with kilopascals in the From box and atmospheres in the To box, ahead of whatever pair you converted last, and the list under the answer carries the same pressure in pascals, bar, pounds per square inch and atmospheres, with millimetres of mercury behind the uncommon units switch. It changes the units on a number and nothing else: a converted figure is still just a quantity, and what a given pressure means in a given setting is not something arithmetic can tell you.
1 kPa in every pressure unit
Common questions
- How many atm is 1 kPa?
- 0.00986923266716 atm, which is 1,000 / 101,325. It scales straight up: 10 kPa is 0.0986923266716 atm, 50 kPa is 0.493461633358 atm, 100 kPa is 0.986923266716 atm, 200 kPa is 1.97384653343 atm and 1,000 kPa is 9.86923266716 atm. Answers print to twelve significant digits, so the repeating decimal behind the division is rounded for display rather than run out to the last place.
- What is the formula for kPa to atm?
- Atmospheres = kilopascals / 101.325, and kilopascals = atmospheres × 101.325 in the other direction, so 0.5 atm is 50.6625 kPa, 2 atm is 202.65 kPa and 3 atm is 303.975 kPa. The 101.325 is a definition rather than a measurement: the 10th General Conference on Weights and Measures fixed one standard atmosphere at exactly 101,325 Pa in 1954, so the factor is exact and is not revised. The Swap units button between the two boxes reverses the pair, which turns this page into an atm to kPa converter without a reload.
- Is 100 kPa one atmosphere?
- No, 100 kPa is exactly one bar, and that is a different unit. A bar is defined as 100,000 pascals and an atmosphere as 101,325 pascals, so 100 kPa comes out as 0.986923266716 atm, about 1.3 percent short, and one atmosphere is 101.325 kPa or 1.01325 bar. The gap is small enough to ignore in rough talk and large enough to matter in arithmetic, so the converter shows both: type 100 in the From box and the list under the answer reads 1 bar and 0.986923266716 atm on the same screen.
- How do I convert MPa, hPa or millibars here?
- Scale them into kilopascals first, because the pressure list holds pascals, kilopascals, bar, psi and atmospheres, plus millimetres of mercury behind the uncommon units switch, and none of those three. A megapascal is 1,000 kPa, so 1 MPa is 9.86923266716 atm. A hectopascal and a millibar are both 0.1 kPa, so the 1,013.25 hPa often quoted as sea-level pressure is 101.325 kPa, which this page shows as exactly 1 atm. Divide hPa or mbar by ten, multiply MPa by a thousand, and type the result.
- What else does it show for the same pressure?
- Every other unit in the category at once, rather than one target at a time. For 100 kPa the list reads 100,000 Pa, 1 bar, 14.503773773 psi and 0.986923266716 atm, and switching on Uncommon units in the readout strip, labelled Show 1 more, adds 750.061575846 mmHg. The heading above the list names what you asked for, in the form 100 kPa in every pressure unit. Copy result copies the headline number without the thousands separators, and every row in the list carries its own Copy button.
- Does it matter whether my figure is gauge or absolute?
- It matters for what the figure describes, and the converter cannot tell the two apart: it changes units and never adds or removes an atmosphere on your behalf. A reading of 220 kPa stated absolutely is 2.17123118678 atm. The same 220 kPa read off a gauge that sits at zero in open air describes 321.325 kPa absolute, which is 3.17123118678 atm, a whole atmosphere higher. Settle which convention your number uses before you convert it, because nothing in the arithmetic will flag the mix-up.
- Why did a small number come out as 9.869233e-7?
- Because results below 0.000001 switch to exponential notation, which is easier to read than a row of zeroes. 0.0001 kPa is 9.869233e-7 atm, while 0.001 kPa still prints in full as 0.00000986923266716 atm. Above that everything is decimal with thousands separators, so 100,000 kPa reads 986.923266716 atm. Typing is forgiving in one direction only: 1,234.5 with a thousands comma in it is accepted, while anything that is not a number turns the answer back to Ready and prints a line under the stage saying what a number here looks like.
- Why does the page open on kPa and atm when I last converted something else?
- Because a page that names a pair should show that pair. This one sets kilopascals and atmospheres on arrival, ahead of whatever the converter last remembered, and it leaves the main unit converter's own pair alone: go back there and it is still on the units you left it on. The number you last typed does travel with you, along with the uncommon units switch, since that is usually the figure you are still working on.
Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.