Scientific Unit Converter
Pressure, radiation, energy and more
The units that never appear in everyday converters: pascals, sieverts, moles, lux, teslas and friends.
Scientific Unit Converter
Runs in your browser · nothing uploaded| Unit | Symbol | Value |
|---|---|---|
| Pascal | Pa | 101,325 |
| Kilopascal | kPa | 101.325 |
| Megapascal | MPa | 0.101325 |
| Bar | bar | 1.01325 |
| Millibar | mbar | 1,013.25 |
| Torr | Torr | 760 |
| Millimetre of mercury | mmHg | 759.9998917 |
| Pounds per square inch | psi | 14.69594878 |
| Inch of water | inH₂O | 406.7824781 |
Gauge and absolute pressure differ by one atmosphere. These are straight unit conversions and assume both sides use the same reference.
01 — How to use Scientific Unit Converter
02 — Getting good results
03 — Questions
No. All the factors are built into the page, and the arithmetic runs in this browser tab.
The exact SI values fixed by the 2019 redefinition where they exist: the elementary charge is exactly 1.602176634 × 10⁻¹⁹ C and the Avogadro constant exactly 6.02214076 × 10²³ per mole. One atmosphere is exactly 101325 Pa by definition.
Because published work still uses them. Viscosity is routinely quoted in centipoise, magnetic field strength in gauss, and energy in ergs, particularly in older literature. Converting them is exactly why a scientific converter exists.
Because these quantities span enormous ranges and a precision that suits pressure in bar is useless for energy in electronvolts. Ten significant figures is well within what double-precision arithmetic holds exactly, so nothing shown is rounding noise.
04 — More about Scientific Unit Converter
Dimensional equivalence is not physical equivalence
The clearest example in this tool is radiation. The gray and the sievert have identical dimensions — joules per kilogram — and the conversion between them is a factor of one. They measure different things. The gray is a physical quantity: how much energy a kilogram of material absorbed. The sievert is a protection quantity: that energy weighted by how damaging the particular radiation is to living tissue, and by which tissue absorbed it. For X-rays, gamma and beta radiation the weighting factor is 1 and the two numbers coincide; for alpha particles it is 20, and for neutrons it varies with energy. A converter that silently treats them as the same unit is arithmetically correct and can mislead by a factor of twenty, which is why this one says so explicitly rather than leaving the reader to know.
Why the SI constants became exact
Until 2019, several SI base units were defined by physical artefacts or by measurement — the kilogram most famously, as a platinum-iridium cylinder in a vault near Paris whose mass was drifting relative to its copies. The redefinition inverted the relationship: instead of measuring constants against units, the constants were fixed by definition and the units now follow from them. The Planck constant, the elementary charge, the Boltzmann constant and the Avogadro constant all became exact numbers with no uncertainty. The practical consequence for a converter is that several factors that were once experimental values with error bars are now exact, which is why this tool can state the electronvolt and the mole to their full digits without qualification.
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