Molarity Calculator

1. In Solve for, choose Molarity (M), Amount of solute (n), or Volume of solution (V).
2. Enter the other two known values in the visible fields and choose their units.
3. For mass input, choose g (mass) or mg (mass). The tool needs a positive Molar mass of solute (g/mol) to convert that mass to moles.
4. Select Calculate, review the result and Formula & steps, or select Reset to clear the form.

Formula and Supported Calculation Paths

The tool uses M = n / V, where M is molarity, n is the amount in moles, and V is volume in liters. It rearranges the equation to n = M × V or V = n / M when you select those targets. For g (mass) or mg (mass) input, it first uses n = mass / molar mass.

Inputs and Supported Units

• Amount of solute (n): mol, mmol, µmol, g (mass), or mg (mass). Direct mmol and µmol values are converted internally to mol.
• Volume of solution (V): Liters (L), Milliliters (mL), or Microliters (µL).
• Molarity (M): mol/L (M), mmol/L (mM), or µmol/L (µM).

Input Rules and Validation

Enter ordinary signed decimal numbers, such as 0.5 or -1. Scientific notation such as 1e-3 is not accepted. Required values must be positive, finite, and no larger than 1e12; empty, non-numeric, zero, and negative values are rejected. A positive molar mass is required when mass is converted to moles. The calculated result must also be finite and positive.

Mass-Output Limitation

Do not rely on a mass result when Solve for is Amount of solute (n) and the amount unit is g (mass) or mg (mass). In this path, the current implementation hides Molar mass of solute (g/mol), does not validate or collect it, and passes no molar mass to the mass conversion. The resulting value can therefore be incorrect or zero-like. Use a direct amount unit such as mol, mmol, or µmol for this target until that implementation issue is corrected.

Results, Copying, and Downloading

After Calculate, the result shows the selected quantity, normalized values, the formula, and calculation steps. Mass input includes an explicit mass-to-moles step. Select Copy result to copy the generated plain text when clipboard access succeeds. If it fails, the interface displays “Could not copy - select and copy manually.” Select Download result (.txt) to create molarity-calculator-result.txt.

Scope and Limitations

The tool performs deterministic unit conversion and arithmetic. It does not look up or infer molar mass, density, or other compound properties, and it does not model temperature-dependent volume, density effects, volume changes on dissolution, or non-ideal behavior. The implementation does not verify whether a solute is fully dissolved, uniformly distributed, or whether entered volume is the final solution volume.

Calculator arithmetic runs in browser JavaScript, and the calculator script contains no submission request for calculation values. The page also loads analytics scripts and includes a separate subscription form that posts to /assets/subscribe.php; the inspected files do not establish the page’s complete analytics, logging, or server-side privacy behavior.

Frequently Asked Questions