Molarity calculator — Use the relation M = mass / (MW × V) between mass, molecular weight, and volume to calculate how much reagent to weigh and what volume to dissolve it in to obtain a target molarity (mol/L).

(1) Prepare stock solutions from powder reagents (e.g., Tris base MW 121.14 → 1 M Tris stock) (2) Calculate component masses for buffers (PBS, TBS, HEPES, etc.) (3) Prepare working solutions of enzymes, substrates, inhibitors (kinase assay, IC50) (4) Calculate concentrations of cell culture additives (drugs, hormones)

Enter any 3 of the 4 values and the remaining one is auto-calculated: ① Mass (mg/g) ② MW (g/mol — check reagent bottle label or PubChem) ③ Volume (mL/L) ④ Concentration (mM/µM/M) Most common use: enter MW, target concentration, and volume to get the mass (mg) to weigh out. Unit prefixes (mM/µM/nM) auto-convert.

Example 1) Make 100 mL of 1 M Tris-HCl (MW 157.6) → Mass = 1 × 157.6 × 0.1 = 15.76 g → Weigh 15.76 g Tris-HCl → dissolve in 80 mL water, adjust pH, then fill up to 100 mL Example 2) 1 mL of 10 µM Doxorubicin (MW 579.98) stock → Mass = 10×10⁻⁶ × 579.98 × 0.001 = 5.80 µg → Dissolve 5.80 µg in 1 mL DMSO (in practice, dilute 5 µL of 10 mM stock)