Convert molar flow rate between mol/s, mol/min, mol/h and kmol units.
Fluids • 6 units
All 6 units on the Molar Flow Rate Converter are defined against the Mole/second (mol/s), so each result is one conversion factor away from a single reference rather than the end of a chain of roundings.
The conversion this page is most often opened for is ready before you type anything: 1 mol/s = 3,599.99712 mol/h. Change either side and every row in the table recalculates with it.
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The steps on this page are all plain time conversions — 1 mol/s is 3,600 mol/h and 3.6 kmol/h — but the useful work happens when a mass flow is turned into a molar one. An ammonia stream running at 1,000 kg/h has a molar flow of about 58.7 kmol/h at 17.03 g/mol, and it is that figure, not the tonnage, that has to balance against the hydrogen and nitrogen feeding it.
Converting a gas flow into molar terms introduces a reference-condition problem that catches people out. One kilomole of an ideal gas occupies 22.414 m³ at 0 °C and 101.325 kPa, but 23.645 m³ at 15 °C and 24.055 m³ at 20 °C. Since different industries anchor their normal and standard cubic metres to different temperatures, a volumetric gas flow converted to kmol/h without stating which reference was used carries a systematic error of several percent that no amount of downstream precision will remove.
Molar flow is also the natural unit for expressing conversion and yield, because those are ratios of molecules rather than of masses. Stating that a reactor converts 85% of its feed only means something in molar terms; the same reaction expressed by mass gives a different number whenever the products weigh differently from the reactants. Keeping a flowsheet's balances in kmol/h and converting to tonnes only at the plant boundary avoids reconciling two sets of figures that were never meant to agree.
Quick reference — 1 Mole/second (mol/s) is equal to:
| Millimole/second | mmol/s | 1,000 |
| Mole/minute | mol/min | 59.999880 |
| Mole/hour | mol/h | 3,599.997120 |
| Kilomole/second | kmol/s | 0.001 |
| Kilomole/hour | kmol/h | 3.599997 |
6 units of molar flow rate, each a fixed multiple of the mol/s. The table spans 3,599,997:1, from mol/h (0.000277778 mol/s) to kmol/s (1000 mol/s). Conversion is one multiplication into the base unit and one division out of it, with no lookup table and no approximation.
value_to = value_from × (factor_from ÷ factor_to)1 mol/s = 1 mol/s1 mmol/s = 0.001 mol/s1 mol/min = 0.0166667 mol/s1 mol/h = 0.000277778 mol/s1 kmol/s = 1000 mol/s1 kmol/h = 0.277778 mol/swhere:
Assumptions: Factors are exact definitions. Full double precision is carried internally and rounding is applied only for display.
Result25 mol/s = 89999.9 mol/h
Molar flow rate is amount of substance per unit time, in moles per second (mol/s). Chemical reactions combine in fixed molecular ratios rather than fixed mass ratios, so a reactor balance written in kilograms has to be converted before it means anything.
The distinction is easiest to see in a simple reaction: hydrogen and oxygen combine two moles to one, but by mass that ratio is about 1 to 8, because an oxygen molecule is sixteen times heavier than a hydrogen one. Feed a reactor on a mass ratio derived from the molar equation without converting, and one reagent is in large excess. Molar flow keeps stoichiometry visible; mass flow hides it.