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Pressure Converter

Converts pressure between pascals (Pa to MPa), bar/millibar, standard atmospheres, psi and ksi, millimetres and inches of mercury, torr and technical atmospheres (kgf/cm²) using NIST factors (1 psi = 6894.757293168 Pa, 1 atm = 101325 Pa).

ValueAmount to convert, expressed in from_unit. From unitUnit of the input value. Accepted symbols: Pa, hPa, kPa, MPa, bar, mbar, atm, psi, ksi, mmHg, torr, inHg, kgf/cm2; spelled-out names and common abbreviations are accepted too. To unitUnit to convert into (same symbols as from_unit).

When to use

You need tyre, weather, hydraulic, vacuum or blood pressure in another unit, e.g. psi to bar, atm to kPa or mmHg to kPa.

Do not use when: You need to compute pressure from force and area (a physics calculation, not a unit conversion) or the gas law relation between pressure, volume and temperature (use ideal-gas-law).

Formula

result = value × factor, factor = (1 from_unit in Pa) / (1 to_unit in Pa)

mmHg uses the conventional value 133.322387415 Pa (mercury density 13.5951 g/cm³ at 0 °C); torr is defined as exactly 1/760 atm, so 1 mmHg ≈ 1.000000142 torr. inHg = 25.4 mmHg.

Inputs

Parameter	Type	Required	Description
`value`	number	yes	Amount to convert, expressed in from_unit.
`from_unit`	enum: Pa \| hPa \| kPa \| MPa \| bar \| mbar \| atm \| psi \| ksi \| mmHg \| torr \| inHg \| kgf/cm2	yes	Unit of the input value. Accepted symbols: Pa, hPa, kPa, MPa, bar, mbar, atm, psi, ksi, mmHg, torr, inHg, kgf/cm2; spelled-out names and common abbreviations are accepted too.
`to_unit`	enum: Pa \| hPa \| kPa \| MPa \| bar \| mbar \| atm \| psi \| ksi \| mmHg \| torr \| inHg \| kgf/cm2	yes	Unit to convert into (same symbols as from_unit).

Outputs

Output	Type	Description
`result`	number	Converted value expressed in to_unit (rounded to 6 decimals; see result_text for very small or very large values).
`result_text`	string	The conversion as text with 6 significant figures, e.g. "5 mi = 8.04672 km".
`formula`	string	Relation used, e.g. "1 mi = 1.609344 km".
`factor`	number	Multiplier from from_unit to to_unit (result = value × factor); absent for non-linear conversions.
`conversion_table`	object	The input value expressed in every supported pressure unit (6 significant figures), keyed by unit symbol.

Example

1 atm to psi: {"value":1,"from_unit":"atm","to_unit":"psi"} → {"result":14.695949,"formula":"1 atm = 14.69594878 psi","conversion_table":{"bar":1.01325,"mmHg":760,"kPa":101.325,"torr":760}}

32 psi to bar: {"value":32,"from_unit":"psi","to_unit":"bar"} → {"result":2.206322,"conversion_table":{"kPa":220.632,"atm":2.17747}}

GET https://tttkmbb.com/api/v1/calculate/pressure?value=1&from_unit=atm&to_unit=psi

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/pressure (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/pressure · Markdown: https://tttkmbb.com/conversion/pressure.md · JSON definition: https://tttkmbb.com/conversion/pressure.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="pressure"
OpenAPI operationId: convert_pressure
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

Is bar the same as atmosphere?

No. 1 bar = 100,000 Pa exactly; 1 atm = 101,325 Pa = 1.01325 bar = 14.6959 psi.

Gauge or absolute pressure?

The converter changes units only. Tyre gauges read pressure above atmospheric (psig); add 1 atm (14.6959 psi) for absolute pressure.

Related calculators

Force Converter — Convert the force units behind psi and kgf/cm².
Ideal Gas Law Calculator — Pressure–volume–temperature of a gas.
Density Converter — Hydrostatic pressure needs fluid density.