Barometric Pressure Conversion Calculator
Convert any barometric pressure reading between the eight most common units used in meteorology, aviation and science — and instantly see where the value sits on the typical sea-level weather scale.
From unit
To unit
Pressure expressed in the target unit
- 1
Convert to pascals
1,013.25 hPa × 100 = 101,325All conversions route through pascals, the SI pressure base unit. - 2
Convert to inHg
101,325 ÷ 3,386.389 = 29.9213
How does this calculator work?
Barometric pressure units all convert through pascals: multiply by the source factor, divide by the target. Standard sea level = 1,013.25 hPa = 29.92 inHg = 760 mmHg = 1 atm. Values below ~980 hPa indicate stormy weather; above ~1,030 hPa signals stable, settled conditions.
Formula
How this is calculated
Every pressure unit can be expressed as a fixed number of pascals (Pa) — the SI base unit. hPa and mbar are identical (1 hPa = 1 mbar = 100 Pa). One standard atmosphere is exactly 101,325 Pa; one inch of mercury is 3,386.389 Pa; one millimetre of mercury is 133.322 Pa; one psi is 6,894.757 Pa. To convert, the input is first multiplied by its unit factor to give the equivalent in pascals, then divided by the target unit factor.
Barometric pressure at sea level normally ranges between about 940 hPa (deep storms) and 1,060 hPa (very settled, cold high-pressure systems). Standard sea-level pressure is 1,013.25 hPa (= 29.92 inHg = 760 mmHg = 1 atm). The weather context bar shows where your value falls within this range.
Factors for hPa, mbar, Pa, kPa and atm are exact by definition. The inHg, mmHg and psi factors are conventional approximations, so results are accurate to about six significant figures. This converter handles absolute (not gauge) pressure and does not adjust for temperature or local gravity.
Frequently asked questions
Standard atmospheric pressure at sea level is 1,013.25 hPa (= 29.9212 inHg = 760 mmHg = 101,325 Pa = 1 atm). Weather forecasts usually quote hPa in most countries and inHg in the United States.
Yes — 1 hPa (hectopascal) equals exactly 1 mbar (millibar). Meteorological organisations switched from mbar to hPa in the 1980s for consistency with SI, but the numeric values are identical, so old and new weather charts can be compared directly.
A pressure below about 980 hPa (28.94 inHg) usually indicates a strong low-pressure system or storm. Pressures below 960 hPa are associated with powerful cyclones and hurricanes. The precise threshold depends on the region and season.
TG we-Calculate Editorial Team. (2026). Barometric Pressure Conversion Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/barometric-pressure-conversion-calculator
TG we-Calculate Editorial Team. "Barometric Pressure Conversion Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/barometric-pressure-conversion-calculator.
TG we-Calculate Editorial Team, "Barometric Pressure Conversion Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/barometric-pressure-conversion-calculator
@misc{wecalculate_barometric_pressure_conversion_calculator, title = {Barometric Pressure Conversion Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/barometric-pressure-conversion-calculator}}, year = {2026}, note = {TG we-Calculate} }
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