Free AI-Assisted

Molarity Calculator for Solution Prep

Weigh powder with hydrate and purity correction, dilute stock, and get bench protocols—no account. Built-in AI agent assistant support.

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Key facts

Key facts about Molarity Calculator for Solution Prep
FactValue
ModesPowder → Solution, Dilution, Serial dilution (tabs)
Powder solve-forMass, Volume, or Molarity (two known values; third calculated live)
Hydrate & purityAnhydrous MW (g/mol); hydrate notation; purity % (default 100)
Concentration unitsPowder: µM, mM, M. Dilution: M, mM, µM, nM, mg/mL, µg/µL, ng/µL, %
Serial dilution1–50 steps; final volume per step in µL; lightweight step table
Pipette warningFlags transfer volumes below 0.5 µL; links to Serial Dilution Planner
Saved recipesUp to 50 named recipes in browser storage; Export/Import JSON
Runs in browserYes — no install
Account requiredNo

What it does

A molarity calculator for bench scientists who need the right mass on the first weigh—not a second attempt after a failed assay. Enter anhydrous molecular weight, hydrate notation (e.g. ·5H₂O), and bottle purity; solve for mass, reconstitution volume, or verified concentration. Results update on every keystroke.

On Powder → Solution, toggle Solve for (Mass, Volume, or Molarity) with unit dropdowns. Dilution applies C₁V₁=C₂V₂; chain from powder with one click. Serial dilution builds a 1–50 step table. Copy bench protocols, print, share a link, or save named recipes locally—no account.

Why researchers use it

  • Correct weighed mass for hydrated salts and supplier purity
  • Avoid unit conversion and dilution math errors
  • Get bench-ready prep steps in plain language instantly
  • Reuse saved recipes without retyping numbers
  • Spot sub-pipette transfer volumes before wet work
  • Chain powder prep into stock dilution in one session

Best for

  • Preparing buffers and media from powder
  • Weighing hydrated salts (e.g. CuSO₄·5H₂O)
  • Diluting stock to a working concentration
  • Verifying concentration after reconstitution
  • Estimating serial dilution before pipette planning
  • Training students on molarity and dilution workflows

When to use this vs alternatives

Choose this tool when you are weighing powder, correcting for hydrate or purity, running a single C₁V₁ dilution, or need a quick serial estimate with shareable protocols in one browser tab. Use the Serial Dilution Planner when you need pipette-aware rounding, 96/384-well plate maps, or Log10 export for dose-response setup. Vendor acid/base apps and spreadsheets still fit familiar one-off dilutions you already trust.

What makes it different

Sigma-Aldrich, Thermo DailyCalcs, and GraphPad QuickCalcs handle basic molarity math but usually ignore hydrate water and bottle purity, so weighed mass is often too low and solutions end up under-concentrated. They rarely give step-by-step prep instructions you can paste into a notebook.

This browser tool combines powder prep, dilution, and a serial table in one workspace with live results, hydrate parsing, purity adjustment, saved recipes, and shareable links—no install. When volumes fall below 0.5 µL, it warns you and hands off to the Serial Dilution Planner for pipette rounding and plate maps.

How to get started

  1. Open the workspace and select Powder → Solution, Dilution, or Serial dilution.
  2. On Powder, set Solve for (Mass, Volume, or Molarity); enter Molecular weight — anhydrous, Hydrate, Purity (%), and your two known values.
  3. Review the Result panel and Bench protocol; note effective MW and any warnings.
  4. Switch to Dilution and click Use powder result as stock if chaining—or enter stock, target, and Final volume (V₂).
  5. Click Copy protocol, PDF / Print, Share link, or enter a name and Save recipe.
  6. If a transfer is below 0.5 µL, follow Open full serial dilution planner → for pipette-rounded volumes.

Frequently asked questions

How does hydrate notation affect the mass I need to weigh?
Hydrated salts include water of crystallization that adds to formula weight—using anhydrous MW for CuSO₄·5H₂O gives far too little powder. Enter anhydrous MW and hydrate notation (e.g. ·5H₂O); the calculator adds water mass and shows Effective MW. Weigh the purity-adjusted mass shown.
Why should I enter reagent purity when making a solution?
Supplier labels list assay or purity below 100%. Ignoring purity means you weigh too little active ingredient and the solution is under-concentrated. Enter Purity (%) from the bottle (default 100). The calculator divides required mass by purity/100 so the dissolved active amount matches your target molarity.
What can I solve for on the Powder → Solution tab?
Toggle Solve for among Mass, Volume, and Molarity. Mass: grams to weigh for a target concentration and final volume. Volume: reconstitution volume for a weighed amount at target molarity. Molarity: verify concentration after dissolving a known mass in a known volume. Results update live as you type.
How does the Dilution tab use C₁V₁=C₂V₂?
Enter Stock concentration (C₁), Target concentration (C₂), and Final volume (V₂) with matching units. For mass-based units, also enter Molecular weight (g/mol). The calculator returns stock volume to pipette and diluent volume. Stock must exceed target (C₁ > C₂).
What happens when a dilution volume is below 0.5 µL?
Volumes below 0.5 µL are impractical for standard micropipettes. The tool flags the step and shows Open full serial dilution planner → for pipette-aware rounding and optional 96/384-well plate maps. The Serial dilution tab gives a quick step table; use the planner before wet work.
How do saved recipes and share links differ?
Share link copies a URL with your full calculation state in the hash. Save recipe stores a named entry in your browser (up to 50) via Saved recipes; use Export JSON / Import to move recipes between machines. Neither requires an account.

Client source code & registry

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