Enter the concentration in µg/mL and the molecular weight in g/mol into the calculator to convert to µM (micromolar).

µg/mL to µM Calculator

Enter any 2 values to calculate the missing variable

Common Mistakes Quick tips
  • Not following the “enter any two values” rule. You must fill exactly two of the three fields (Concentration, Molecular Weight, Result), leaving one blank to compute.
  • Mixing up mass units:
    • mg/mL is 1000× larger than µg/mL.
    • µg/L is 0.001× µg/mL.
    • mg/L is numerically equal to µg/mL (1 mg/L = 1 µg/mL).
  • Choosing the wrong molecular-weight unit:
    • kDa vs Da: 50 kDa = 50,000 g/mol. If the unit is set to “Da” but you type 50, you’ll be off by 1000×.
    • mg/mol vs g/mol: entering a g/mol value while “mg/mol” is selected causes a 1000× error.
    • Da is treated numerically the same as g/mol in this tool.
  • Using the wrong molar mass for the compound form. Use the molar mass of the actual species in solution (e.g., salt or hydrate), not the free base/acid unless that’s what you prepared.
  • Reading the result in the wrong unit. mM, µM, nM, and pM differ by powers of 1000; a unit mismatch causes 10³–10⁶ errors.
  • Entering zero or negative values. Molecular weight and concentration must be positive; zero will trigger an error.
  • Applying this to mixtures/polymers with broad MW distributions. Results will be approximate at best.
When to Use This Calculator
  • Convert a mass concentration (µg/mL, mg/mL, µg/L, mg/L) to molarity (µM, mM, nM, pM) when the molecular weight is known.
  • Determine what mass concentration you need to reach a target molarity for solution prep.
  • Solve for molecular weight from known mass concentration and molarity (sanity-checks for compounds, peptides, or oligomers).
  • Standardize units across protocols, publications, or instruments that report different units.
  • Not a dilution or %w/v calculator—use a dedicated dilution tool to compute mix volumes.
Input Definitions
  • Concentration — mass per volume of the solute.
    • µg/mL — micrograms per milliliter (base mass unit in this tool).
    • mg/mL — milligrams per milliliter (1 mg/mL = 1000 µg/mL).
    • µg/L — micrograms per liter (1 µg/L = 0.001 µg/mL).
    • mg/L — milligrams per liter (1 mg/L = 1 µg/mL).
  • Molecular Weight (Molar Mass) — mass of one mole of the compound.
    • g/mol — base unit.
    • mg/mol — 0.001 g/mol.
    • kDa — kilodalton (1 kDa = 1000 g/mol).
    • Da — dalton (numerically equal to g/mol for molar mass entries).
  • Result — molar concentration of the solution.
    • µM — micromolar (base molar unit in this tool).
    • mM — millimolar (1 mM = 1000 µM).
    • nM — nanomolar (1 µM = 1000 nM).
    • pM — picomolar (1 µM = 1,000,000 pM).
  • Formulas used
    • µM = (µg/mL ÷ g/mol) × 1000
    • µg/mL = (µM × g/mol) ÷ 1000
    • g/mol = (µg/mL ÷ µM) × 1000

µg/mL to µM Conversion Formula

The following formula is used to convert µg/mL to µM.

µM = (µg/mL / MW) * 1000

Variables:

  • µM is the concentration in micromolar
  • µg/mL is the concentration in micrograms per milliliter
  • MW is the molecular weight in grams per mole (g/mol)

To convert µg/mL to µM, divide the concentration in µg/mL by the molecular weight in g/mol and then multiply by 1000 to convert to micromolar.

What is µg/mL to µM Conversion?

Converting µg/mL to µM is a common task in chemistry and biology, particularly in the context of preparing solutions for experiments. The concentration in µg/mL measures the mass of a substance in micrograms present in one milliliter of solution, while µM is a measure of the number of moles of a substance in one liter of solution. This conversion is necessary when the molecular weight of the substance is known and one needs to express concentration in terms of molarity, which is a more useful unit in chemical reactions.

How to Calculate µg/mL to µM?

The following steps outline how to convert µg/mL to µM.

  1. First, determine the concentration in µg/mL.
  2. Next, determine the molecular weight (MW) of the substance in g/mol.
  3. Use the formula µM = (µg/mL / MW) * 1000.
  4. Finally, calculate the concentration in µM.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Concentration (µg/mL) = 150 µg/mL

Molecular Weight (g/mol) = 300 g/mol