Molar Flow Rate Converter

Convert non-negative amount flow rate between mol/s, mol/min, mol/h, kmol/s, kmol/h, mmol/s, lb-mol/s, and lb-mol/h for process and gas-system work.

Amount flow

Convert molar flow rate across SI and pound-mole units

Translate a stated amount-of-substance flow without mixing it up with mass flow or volumetric flow.

Quick presets

Scope note

This page converts amount flow rate only. It does not infer mass flow, volumetric flow, or composition-specific relationships, and the pound-mole entries remain amount units rather than mass units.

Enter values Provide a molar flow rate and source unit to calculate the full conversion sheet.

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Fluid & Process Systems

Molar flow rate converter: mol/s, kmol/h, lb-mol/h, and amount-flow units explained

A molar flow rate converter rewrites the same amount-of-substance throughput in the unit your process sheet, gas-property workflow, or reaction-balance calculation expects. That matters because amount flow is not the same quantity as mass flow or volumetric flow, even when the numbers appear in the same model.

What amount flow rate measures

Amount flow rate measures how much amount of substance crosses a boundary per unit time. It can be written as mol/s, mol/min, kmol/h, or lb-mol/h without changing the underlying throughput being described.

That makes it useful in reaction engineering, gas handling, and composition-based process work where the count of entities matters more than total mass alone.

ṅ = n / t

Defines amount flow rate as amount of substance divided by time.

ṅ = ṁ / M

Shows the link between mass flow rate and amount flow rate when molar mass is known.

1 kmol/h = 1,000 mol/h

Links the common SI reporting scales used by this page.

Why it is not the same as mass flow or volume flow

Mass flow rate and volumetric flow rate describe different physical quantities. You can move between them only when you know additional information such as molar mass, temperature, pressure, density, or composition.

This page therefore converts the stated amount-flow value only. It does not estimate pipe flow, gas volume, or stream mass without those separate assumptions.

Why the pound-mole label needs care

The pound-mole is a customary engineering amount unit used in some US process and gas-system references. It is not an SI unit and should not be treated as mass flow just because the word pound appears in the label.

Keeping the converter framed as amount flow avoids mistakes between lb-mol/h and lb/h, which are different quantities with different physical meanings.

Further reading

Frequently asked questions

What is the difference between molar flow rate and mass flow rate?

Molar flow rate measures amount of substance per unit time, while mass flow rate measures mass per unit time. You need molar mass to convert between them.

 Is lb-mol an SI unit?

No. It is a customary engineering amount unit. The SI unit for amount of substance is the mole.

 Can this page convert mol/s to m³/s?

Not by itself. Converting amount flow to volumetric flow requires additional assumptions such as temperature, pressure, and composition.

 Why do process calculations sometimes use kmol/h instead of mol/s?

Both are valid. `mol/s` fits equation-based analysis, while `kmol/h` often matches plant reporting and larger industrial flow scales more naturally.

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