Exact conversion factors for the older units still printed on gauges, in patents, and in papers from before SI: atmospheres, Torr, mmHg, psi, calories, electronvolts, poise, and kilogram-force.
| Quantity | Unit | Multiply by to get SI | Note |
|---|---|---|---|
| Pressure (to Pa) | pascal (Pa) | 1 | |
| Pressure (to Pa) | kilopascal (kPa) | 1000 | |
| Pressure (to Pa) | bar | 1.000000e+5 | exact: 1 bar = 100000 Pa |
| Pressure (to Pa) | millibar (mbar) | 100 | |
| Pressure (to Pa) | atmosphere (atm) | 1.013250e+5 | exact by definition |
| Pressure (to Pa) | torr | 133.32236842105263 | exact: atm / 760 |
| Pressure (to Pa) | mm Hg | 133.322387415 | conventional mmHg (differs from Torr in the 5th digit) |
| Pressure (to Pa) | inch Hg (0 °C) | 3386.389 | conventional, at 0 °C |
| Pressure (to Pa) | pound-force / in² (psi) | 6894.757293168 | lbf/in² (defined lbf, inch) |
| Pressure (to Pa) | cm H2O (4 °C) | 98.0665 | conventional |
| Energy (to J) | joule (J) | 1 | |
| Energy (to J) | kilojoule (kJ) | 1000 | |
| Energy (to J) | calorie (thermochemical) | 4.184 | exact by definition |
| Energy (to J) | kilocalorie (thermochemical) | 4184 | exact by definition |
| Energy (to J) | electronvolt (eV) | 1.602177e-19 | 2019 SI exact |
| Energy (to J) | erg | 1.000000e-7 | exact: 1e-7 J |
| Energy (to J) | kilowatt-hour (kWh) | 3.600000e+6 | exact |
| Force (to N) | newton (N) | 1 | |
| Force (to N) | dyne (dyn) | 1.000000e-5 | exact: 1e-5 N |
| Force (to N) | kilogram-force (kgf) | 9.80665 | exact by definition |
| Dynamic viscosity (to Pa s) | pascal-second (Pa·s) | 1 | |
| Dynamic viscosity (to Pa s) | millipascal-second (mPa·s) | 0.001 | |
| Dynamic viscosity (to Pa s) | poise (P) | 0.1 | exact: 0.1 Pa·s |
| Dynamic viscosity (to Pa s) | centipoise (cP) | 0.001 | exact: 1 mPa·s |
BIPM SI Brochure (9th ed.) and conventional definitions: atm = 101325 Pa (exact), Torr = atm/760, mmHg = 133.322387415 Pa, psi from lbf/in^2, cal_th = 4.184 J (exact), eV = 1.602176634e-19 J (2019 SI exact), kgf = 9.80665 N (exact).
Data revision 2026-06-22.
These values are imported from the same data the Aliquot calculators use, so this page cannot drift away from what the tools compute.