1 BarEdit

1 bar is a unit of pressure defined as exactly 100,000 pascals. It is a practical, non-SI unit that has found wide use in engineering, meteorology, and industry because its numbers align well with everyday pressures and with how machines and weather systems are designed and described. In practice, many engineers, technicians, and suppliers prefer to quote pressures in bar because it yields readable figures for components like tires, hydraulic and pneumatic systems, and pressure vessels. The bar sits close to standard atmospheric pressure, so statements such as “about 1 bar” are intuitive in contexts where people already have a sense of air pressure at sea level. The term bar is ubiquitous in parts of the world where manufacturing and automotive industries operate, even as some laboratories and academia favor SI units exclusively. See bar (unit) and Pressure for more on the concept.

In everyday terms, 1 bar is just slightly less than one atmosphere. Specifically, 1 bar equals 100 kilopascals (100,000 pascals). Because the atmosphere at sea level is about 101.3 kilopascals, 1 atm is approximately 1.01325 bar. For readers looking to convert to other common units, 1 bar is roughly 14.5038 pounds per square inch (psi) and 0.986923 standard atmospheres. In scientific notation, these relationships are used across engineering drawings, vehicle specifications, and weather forecasts. See Pounds per square inch and Atmosphere (unit) for context.

Definition and notation - 1 bar = 100,000 pascals, exactly. The bar is a non-SI unit adopted for use with the SI, recognized because it provides a convenient scale for many practical measurements. See Pascal (unit) and Non-SI units for background on how it relates to the SI system and to other common units. - Symbol and spelling: “bar” is used without a prefix or capital letter in routine measurement; higher-precision contexts will still treat it as a standard unit. See Bar (unit) for terminology and conventions.

Conversions and relationships - 1 bar = 100 kPa - 1 bar ≈ 0.986923 atm - 1 bar ≈ 14.5038 psi - 1 atm ≈ 1.01325 bar - 1 bar = 100,000 Pa These relationships make the bar a handy bridge between the metric system and other measurement schemes used in industry and commerce. For a broader view of how pressure units interrelate, see Pressure and Pounds per square inch.

Usage and applications The bar is widely used in many sectors where pressures are common and the numbers are easy to read. In the automotive and manufacturing sectors, tire pressures, hydraulic pressures, and refrigerant pressures are often specified in bar. In hydraulics and pneumatics, designers and technicians frequently choose bar-scale readouts and components to minimize misreads during assembly, testing, and operation. See Hydraulic pressure and Pneumatic system for related concepts.

In weather and climate contexts, the bar remains a practical unit for describing pressure in some regions and equipment, even as meteorologists increasingly use SI-compatible quantities. Scuba diving and other activities that require pressure readings also commonly report in bar, though many readers will encounter atmospheres or psi in other locales. See Meteorology and Scuba diving for broader discussions of pressure in real-world environments.

Standards and regulation The bar is part of the cadre of non-SI units that are officially accepted for use with the SI. Its continued prevalence is largely a function of cross-border manufacturing, supply chains, and legacy instrumentation. While some voices advocate moving exclusively to SI units for clarity and interoperability, the bar’s persistence reflects the value of stable, industry-friendly standards that lower conversion costs and minimize costly redesigns. The bar’s status and definitions are maintained under the general framework of the International System of Units and associated bodies such as the General Conference on Weights and Measures and the Bureau International de Poids et Mesures.

See also - Pressure - Bar (unit) - Pascals - Pounds per square inch - Megapascal - Atmosphere (unit)