Pressure Converter

From tyre gauges to weather reports

Pressure units show up in more places than most people realise: your car or bicycle tyre gauge probably reads in psi, a weather forecast reports atmospheric pressure in hectopascals or millibars, a scuba diving computer or industrial gauge might use bar, and a medical blood pressure reading uses millimetres of mercury (mmHg), which is functionally the same unit as torr. This tool converts between pascal, kilopascal, bar, atmosphere, psi, and torr so you can move between whichever pair a device, manual, or report happens to use.

How these units relate to each other

The pascal, the SI unit for pressure, is defined as one newton of force per square metre — a genuinely tiny amount of pressure, which is why larger multiples like the kilopascal and bar are more commonly used in practice. One bar is defined as exactly 100,000 pascals, and is close to (but not identical to) standard atmospheric pressure at sea level, which is instead defined as exactly 101,325 pascals and given its own unit, the atmosphere (atm). Psi (pounds per square inch) is the standard unit in the US for tyre pressure and many industrial specifications, while torr — nearly identical to mmHg — remains standard in medicine and some scientific vacuum measurements.

Where mix-ups commonly happen

A frequent real-world error is misreading a tyre pressure specification: a passenger car tyre is typically inflated to around 30–35 psi, which is roughly 2.1–2.4 bar — mistaking one for the other, especially when a pressure gauge or pump only displays one unit, can lead to a dangerously under- or over-inflated tyre. Weather reports add another wrinkle: some countries report atmospheric pressure in hectopascals (equivalent to millibars) while others use inches of mercury, and this converter's pascal/kilopascal units let you bridge to either by using the well-known 1 hPa = 100 Pa relationship.

Who uses this tool

Drivers and cyclists checking tyre pressure specifications against a pump calibrated in a different unit, scuba divers and industrial technicians converting between bar and psi on equipment gauges, students and lab technicians working through physics or chemistry problems involving atmospheric pressure, and anyone reading an international weather report that uses an unfamiliar pressure unit all benefit from a quick, reliable converter.

A note on precision

For safety-critical applications like tyre inflation, medical equipment, or industrial gas systems, always follow the specific tolerance and rounding guidance provided by the equipment manufacturer rather than relying solely on a general-purpose converter, and double check the converted figure against the equipment's built-in gauge before relying on it.

One more practical example

Home espresso machines and pressure cookers often quote operating pressure in bar, while some older manuals and imported appliances use psi or atm instead — this converter is a fast way to check whether an appliance's stated pressure rating matches what a recipe, warranty document, or safety guideline expects before you rely on it.

Reading equipment gauges correctly

Many analogue pressure gauges display more than one unit around the same dial face, which can make it easy to misread the wrong scale at a glance, particularly under time pressure — cross-checking an unfamiliar gauge reading against this converter before acting on it is a simple habit that can prevent a costly over- or under-pressurisation mistake.