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Lab Unit Converter: Pressure, Vacuum, Temperature & Centrifuge
Convert pressure between mbar, Torr, mmHg, inHg, kPa, bar, atm and psi; turn a vacuum gauge reading into absolute pressure; convert °C, °F and K; and switch centrifuge speed between rpm and g-force (RCF).
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How it works
Absolute pressure = Atmospheric pressure − Gauge vacuum
°F = °C × 9/5 + 32 · K = °C + 273.15
RCF (× g) = 1.118 × 10⁻⁵ × radius (cm) × rpm²
Worked examples
Vacuum gauge shows 27 inHg
27 inHg = 914.3 mbar below atmosphere. Absolute pressure = 1013.25 − 914.3 = about 99 mbar (74 Torr). That is the figure to compare with rotary evaporator solvent charts.
3000 rpm with a 10 cm rotor
RCF = 1.118 × 10⁻⁵ × 10 × 3000² = 1006 × g. A method written in × g can be run on any centrifuge once you know its rotor radius.
Frequently asked questions
Is Torr the same as mmHg?
Almost. 1 Torr = 1/760 atm = 133.322 Pa; 1 mmHg = 133.322 Pa. The difference is less than one part in a million, so labs treat them as equal.
Why does my vacuum gauge read in inHg but the solvent chart uses mbar?
Dial gauges show how far the pressure is below atmosphere (gauge vacuum). Solvent and rotavap charts use absolute pressure. Use the Vacuum gauge tab to convert.
What radius should I use for RCF?
Measure from the centre of the rotor to the bottom of the tube when it is spinning (maximum radius). The centrifuge manual usually gives it.
Why use RCF instead of rpm in methods?
The same rpm gives different forces on rotors of different sizes. RCF (× g) describes the actual force, so results can be repeated on any centrifuge.