Graphpad Molarity Calculator 〈FHD〉

Determining how much solvent is required to reach a specific molarity.

GraphPad, the creators of the industry-standard Prism software, offers this free web-based utility to simplify three specific scenarios:

✅ Bookmark the GraphPad QuickCalcs page – it also has t-test, EC50, dilution, and normality calculators.

Choose what you want to calculate (e.g., "Calculate the mass needed"). Input known values: Molecular Weight: The g/mol of your substance. Desired Concentration: The target molarity (e.g., 50 mM).

You have 2 g of Tris-HCl (MW = 157.6 g/mol) and need a 0.1 M solution. What volume can you make?

Don't forget to account for the "dilution factor" if your stock solution is already in a liquid form. While this tool is great for powder-to-liquid prep, always double-check if you need their Dilution Calculator instead!

7.305 g – weigh this out and dissolve to 250 mL.

This is the most critical step. Ensure the dropdown menus are set to the correct scale (M vs. mM vs. µM). The calculator updates in real-time to show you the result. Practical Lab Tips for Better Results

Is bad math ruining your buffer prep?

Next time you’re at the bench, keep this tool open in a tab—your notebook (and your PI) will thank you.

If your chemical is only 95% pure, remember to divide the calculated mass by 0.95 to get the true amount needed.

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Enter your target concentration (e.g., 50 mM) and your desired final volume (e.g., 250 mL). 4. Choose Your Units