Choose molar concentration, mass concentration or molar mass, then enter the two known values and their units.

Convert mass concentration using the molar mass of the actual solute form.

Use the actual salt, hydrate or molecular species. Da/kDa use the usual practical molar-mass convention.

Common Mistakes Quick tips
  • Choose the quantity to solve for, then enter the two displayed known quantities. The calculated answer appears in the result area.
  • 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: molecular mass of 50 kDa practically corresponds to molar mass of 50,000 g/mol. Entering 50 Da instead changes the value 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 for practical conversions; this is not an exact metrological identity under the current SI.
  • 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.
  • Negative concentrations are invalid and molar mass must be positive. Zero concentration is valid for conversion with a known molar mass; both concentrations must be positive to infer molar mass.
  • 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; its numerical value is multiplied by 1000 for the practical g/mol convention.
    • Da — dalton; numerically treated as g/mol for practical molar-mass entries.
  • Molar concentration — amount of solute per volume of 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 measures micromoles of a substance per 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. The result is (150 ÷ 300) × 1000 = 500 µM.