kPa to Atmospheres Converter
1 atm = 101.325 kPa. Type in either box.
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How many atmospheres is that?
Dividing a kilopascal reading by 101.325 answers a useful question: how does this pressure compare with the air around us?
1 atm = 101.325 kPa exactly
Because the divisor is close to a hundred, the mental version is easy. Move the decimal point two places and knock off about one and a half per cent. 500 kPa is roughly 5 atm; the exact answer is 4.93.
The comparison matters in chemistry, diving and physiology, where what counts is the pressure relative to ordinary air rather than an absolute figure in SI units.
The kilopascal
A thousand pascals, and the size that suits everyday pressures. Car tyres run at roughly 200–250 kPa, the atmosphere sits at about 101 kPa, and a domestic water supply is usually somewhere between 200 and 500 kPa.
It is the working unit for pressure through most of the metric world, which is why tyre placards in Europe, Australia and Asia are marked in kPa alongside the bar figure.
The standard atmosphere
One atmosphere is defined as exactly 101,325 pascals. It was originally meant to represent average air pressure at sea level, and it is close, but it is now a fixed definition rather than a measurement — real sea-level pressure wanders either side of it with the weather.
The unit is used where pressure is being compared to ordinary air: chemistry, diving, aviation and physiology. Ten metres of seawater adds roughly one atmosphere, which is the rule every diver learns first.
The working, step by step
Every line updates with whatever you type above. The point is the method, which is the same for any pair of units in this family.
The same quantity, two different numbers
One physical amount, read off two scales. The tick marks do not line up, and the gap between them is the conversion factor made visible.
How much is that?
A number is easier to judge next to something familiar.
Your turn
Reading a method and being able to use it are different things. Answer within half a per cent and it counts as correct.
Score: 0 of 0
How to use this converter
- Type into either box. The other side updates as you go; there is no button to press.
- Swap the direction with the button between the boxes, carrying your value across.
- Set the decimals if the default is more or less precision than you need.
- Copy the answer with its unit, ready to paste.
- Use the shortcut buttons for the values that come up most often.
- Share the result. The address bar tracks what you type, so the link you copy opens on the same number.
Common uses and tips
Where pressure conversions come up
- Tyres. The single most common reason anyone converts pressure. American placards are in psi, European and Asian ones in bar or kPa, and the three appear side by side on the same door sticker.
- Weather. Forecasts use hectopascals or millibars, which are the same size — 1 hPa is 1 mbar. A typical high-pressure system reads about 1020 of either.
- Diving. Cylinder pressures are in bar almost everywhere and psi in the United States. A full 200 bar cylinder is about 2,900 psi.
- Coffee. Espresso machines are specified in bar; nine bar at the group head is the usual target, which is about 130 psi.
- Materials and hydraulics. Tensile strength and hydraulic ratings come in MPa or psi, and the two communities rarely use the same one.
The trap: gauge pressure and absolute pressure
Almost every pressure you read off a dial in daily life is gauge pressure — how much higher than the surrounding air it is. A tyre at 32 psi contains 32 psi more than the atmosphere, so its absolute pressure is about 46.7 psi.
Conversion between units never changes which of the two you have. If you start with a gauge reading you end with a gauge reading. Where it goes wrong is in physics and chemistry, where the gas laws need absolute pressure: add one atmosphere to a gauge figure before it goes into a calculation. The units psig and psia exist precisely to keep the two apart.
Tips worth knowing
- One bar is not one atmosphere. It is 0.9869 of one. The difference is small enough to ignore for a tyre and large enough to matter in a laboratory.
- Millibars and hectopascals are identical. Weather maps use whichever the local service prefers; the number is the same.
- One MPa is about ten atmospheres, which makes megapascals easy to sanity-check against everyday pressures.
- Torr and mmHg are interchangeable in practice, differing by about one part in seven million.
Values people look up most
Each one opens the converter with the number already in it.
- 50 kPa to atm
- 100 kPa to atm
- 101.325 kPa to atm
- 150 kPa to atm
- 200 kPa to atm
- 250 kPa to atm
- 300 kPa to atm
- 400 kPa to atm
- 500 kPa to atm
- 600 kPa to atm
- 800 kPa to atm
- 1,000 kPa to atm
- 1,500 kPa to atm
- 2,000 kPa to atm
- 5,000 kPa to atm
Quick reference
| Kilopascals | Atmospheres |
|---|---|
| 50 kPa | 0.493462 atm |
| 100 kPa | 0.986923 atm |
| 101.325 kPa | 1 atm |
| 200 kPa | 1.973847 atm |
| 300 kPa | 2.96077 atm |
| 500 kPa | 4.934616 atm |
| 1,000 kPa | 9.869233 atm |
| 2,000 kPa | 19.738465 atm |
| 5,000 kPa | 49.346163 atm |
| 10,000 kPa | 98.692327 atm |
Questions people ask
What is the formula for kPa to atm?
Divide by 101.325.
What is 101.325 kPa in atmospheres?
Exactly 1 atm. That figure is the definition of the standard atmosphere.
What is 200 kPa in atmospheres?
1.97 atm — just under twice atmospheric pressure.
Does this convert gauge or absolute pressure?
Whichever you put in. Converting units does not change which kind of pressure you have — a gauge reading converts to a gauge reading. If a calculation needs absolute pressure, add one atmosphere first.