HesapHanem

Technical Atmosphere to Bar Converter

Enter a pressure in technical atmospheres to convert to bar.

How it is calculated

The tool converts a pressure in technical atmospheres (at, equal to kgf/cm²) with two factors: bar = at × 0.980665 and psi = at × 14.2233. The bar value is shown with four decimals and the psi value with two. Negative numbers are not rejected: they are converted the same way, which is useful for vacuum or gauge readings below zero. The result is a pure unit conversion, so it keeps whatever reference the gauge uses; a gauge reading stays a gauge reading and is not turned into absolute pressure.

Worked example

An old boiler gauge reads 5 at and you want modern units. Bar: 5 × 0.980665 = 4.903325, which the tool rounds to 4.9033 bar. Psi: 5 × 14.2233 = 71.1165, shown as 71.12 psi. So 5 at is slightly less than 5 bar.

Try this example →

Common mistakes

  • Treating 1 at as 1 atm or 1 bar. The technical atmosphere is 0.980665 bar, while a standard atmosphere is 1.01325 bar, so the three differ by a few percent.
  • Confusing at with atm when reading a nameplate; check whether it says kgf/cm² (at) or atm.
  • Assuming the answer is absolute pressure. Most gauges show gauge pressure, and the conversion does not add atmospheric pressure.
  • Using the rounded psi result for fine work: the psi is shown to two decimals only, so keep the bar value for further calculation.

About this calculator

The technical atmosphere (at) is an older metric pressure unit defined as exactly 1 kilogram-force per square centimetre (kgf/cm²), predating the SI pascal and bar. Because 1 kgf = 9.80665 N acting over 1 cm², 1 at = 98,066.5 Pa = 0.980665 bar — almost, but not quite, equal to a standard atmosphere (1 atm = 1.01325 bar).

The unit still shows up on older or Eastern-European-made pressure gauges, boiler and compressor nameplates, and hydraulic system specs, so mechanics and industrial technicians reading legacy equipment need to convert it to the bar or psi values used on modern instruments.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    On old Turkish and Russian gauges you may see atü and ata. The tool does not distinguish them: atü is gauge pressure and ata is absolute, and a reading keeps the reference it came with. So 5 atü is 4.9033 bar gauge, and about one atmosphere has to be added for an absolute value. Negative inputs convert too, handy for vacuum gauges. Which kind of gauge or equipment are you reading?

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators