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Molarity Calculator

Single-solute mode in this free online molarity calculator handles mass, molarity, final-volume and g/L calculations, and liquid acid stocks; protein mode adds kDa-based protein molarity conversions, while multi-solute mode builds lab recipes and stock-multiplier amounts.

Molarity calculator inputs
Calculator mode
Calculation mode
Liquid acid stock
% w/w
g/mL

Offline compound search includes 0 common salts, buffers, sugars, and reagents. Confirm the exact salt, hydrate, and molecular weight against your bottle label.

g/mol

References

Sources for molarity and protein conversions, molecular weights, and liquid-stock properties. Calculations use original Mol Biology Tools code and a curated offline compound list.

  1. Amount concentration, molar mass, and unit terminology: IUPAC Green Book, abridged fourth edition (2023). Protein mass and molarity conversions use the supplied molecular weight.
  2. Molecular formula and molecular-weight checks: PubChem Compound database.
  3. PubChem database background: Kim et al. (2025), PubChem update. This citation describes the database, not the release date of every locally stored compound value.
  4. Moles to molecules: NIST Avogadro constant, exactly 6.02214076 × 1023 mol-1.
  5. Liquid-stock concentration and density checks: Merck inorganic-reagents reference, acid properties (2014). Stock presets are editable starting values, not batch-certified measurements; use the assay and density on your reagent's certificate or SDS.
  6. Chemical safety background: NIOSH Pocket Guide. It is not a substitute for the product-specific SDS or a source of every stock preset.