โ๏ธ Standard Solution Preparation Calculator
Calculate exactly how much solid reagent to weigh, or how much concentrated liquid stock to measure, to prepare a standard solution at your target concentration and volume.
From solid or liquid
Two modes: weigh out a solid reagent, or measure a concentrated liquid stock.
Common units
Molarity, millimolarity, mg/mL, and % w/v for solids; molarity for liquid stocks.
Always free
No sign up, no limits. Calculate as many standard solutions as you need.
Frequently asked questions
When should I prepare a standard from solid vs. from a liquid stock?
Prepare from solid when you're starting fresh from a reference standard powder or reagent โ this calculator gives the exact mass to weigh. Prepare from a concentrated liquid stock when a higher-concentration solution already exists and you need to dilute it down to a working concentration โ this calculator gives the exact stock volume to take.
What's the difference between a stock solution and a working standard?
A stock solution is typically prepared at a high, stable concentration for storage and later dilution. A working standard is the diluted, ready-to-use concentration actually needed for a specific assay or calibration curve, prepared fresh from the stock as needed.
Does the purity of my reagent affect the mass I should weigh?
Yes โ if your reference standard is not 100% pure (check the certificate of analysis), you need to weigh out more than the simple stoichiometric mass to compensate. Use the Purity Correction Calculator alongside this tool to adjust for reagent purity or potency before finalizing your weighed mass.
Accuracy & how this is derived
Derivation: For solid preparation, mass needed is calculated from target concentration and volume using mass = concentration ร volume (adjusted for molar mass where molarity is used). For liquid stock dilution, the standard C1V1=C2V2 dilution equation is applied to determine the stock volume needed.
Validated against: Standard solution preparation methodology consistent with USP General Chapter <11> USP Reference Standards and general analytical chemistry practice.
โ ๏ธ For educational and research support only โ verify critical results independently before use in regulated, clinical, or publication-bound work.
โ Last updated: July 2026 ยท Report an error
Preparing standard solutions in the lab
A standard solution is a solution of precisely known concentration, prepared either by dissolving a weighed mass of solid reagent in solvent up to a fixed volume, or by carefully diluting a concentrated liquid reagent of known purity and density. For solids, the required mass follows mass = concentration ร volume ร molar mass (for molar concentrations), or a direct scaling for mg/mL and % w/v. For concentrated liquid reagents such as acids and bases, the stock's own molarity must first be derived from its density and percentage purity (assay), since commercial concentrated reagents are sold by weight percentage rather than molarity. Always prepare solutions in a volumetric flask rather than a graduated cylinder when precision matters, and always add concentrated acid to water rather than the reverse to control the exothermic reaction safely. For thesis reporting: state the reagent, its purity/grade, the mass or volume measured, the solvent, and the final volume. Example: 'A 0.1 M NaCl standard solution was prepared by dissolving 2.922 g NaCl (ACS grade) in deionized water to a final volume of 500 mL.'