Concentration Unit Converter
Convert between molar, mass-based, and percentage concentrations instantly. Automatically compute all unit equivalents for your molecule of interest.
Input
All Conversions
| Unit | Value |
|---|---|
| Molar (mol/L) | |
| M | 1.000 |
| mM | 1000.00 |
| µM | 1000000.00 |
| nM | 1000000000.00 |
| pM | 1000000000000.00 |
| Mass (g/mL) | |
| mg/mL | — |
| µg/mL | — |
| ng/mL | — |
| pg/mL | — |
| Percentage | |
| %(w/v) | — |
When to Use Molar vs Mass Concentrations
Molar concentration (M, mM, µM, nM, pM) expresses the number of moles of solute per liter of solution. This is ideal for stoichiometric calculations, kinetic experiments, and biochemistry where you need to know the exact number of molecules. Use molar concentrations when the number of particles matters more than the mass.
Mass-based concentration (mg/mL, µg/mL, ng/mL) is common in practical lab work, especially when preparing solutions by weighing. It does not require knowledge of molecular weight during preparation, making it convenient for standard protocols. Conversion to molar concentration requires a separate calculation and the molecular weight.
Percentage concentration (%(w/v), %(v/v)) is often used in older protocols and recipes. %(w/v) means grams of solute per 100 mL of solution; %(v/v) is volume of solute per 100 mL of solution. Both are less precise than molar or mass-based units for modern analytical work.
Common Pitfalls
- • Forgetting that %(w/v) depends on molecular weight: the same %(w/v) of glucose and BSA represent vastly different molar concentrations.
- • Confusing %(v/v) (volume %) with %(w/v): ethanol solutions are often expressed as %(v/v), while proteins are %(w/v).
- • Assuming %(w/v) means "grams per mL": it actually means grams per 100 mL. A 1% (w/v) solution = 10 mg/mL, not 1 mg/mL.
- • Using mass concentration for dilutions in stoichiometric calculations without first converting to molar units.
Microfluidics Relevance
In microfluidic devices, both unit systems are critical. You might design a channel for a specific molar concentration (e.g. 100 µM for enzyme kinetics), but prepare the stock solution by mass (e.g. weighing out BSA in mg/mL). Precise conversion between these units ensures your on-chip concentrations match your intended biochemistry. Mistakes here can lead to failed assays or misinterpreted results in high-throughput screening.
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