Calculate molarity, moles, volume, or mass for a solution using M = n/V, then convert the solved concentration into g/L, mg/mL.
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Chemistry workflow
Move between molarity, moles, volume, and prep mass without leaving the page
Pick the mode that matches the values you already know, then use the result tables below to translate the same solution into concentration, prep-volume, and mass terms.
Quick lab presets
Result sheet
1 M
Calculated from 1 mol in 1 L.
1
Molarity (M)
1
Moles (mol)
1
Volume (L)
58.44
Mass (g)
Interpret the solution strength At 1 M, each 1 mL contains 1 mmol of solute and each 100 μL contains 0.1 mmol. This is a relatively concentrated stock by routine lab standards, so temperature control and the exact final mark matter more than they do for dilute working solutions.
Concentration equivalents
Unit
Value
M
1 M
mM
1,000 mM
uM
1,000,000 uM
nM
1,000,000,000 nM
Mass concentration equivalents
Use these when you need recipe-style units such as g/L or mg/mL rather than mol/L.
Equivalent
Value
g/L
58.44 g/L
mg/mL
58.44 mg/mL
mg/100 mL
5,844 mg/100 mL
Common preparation volumes
Use the solved molarity as a target and read across to see the moles, and optionally the grams, needed for common flask sizes.
Prep size
Moles needed
Mass needed
10 mL prep (10 mL)
0.01 mol
0.58 g
50 mL prep (50 mL)
0.05 mol
2.92 g
100 mL prep (100 mL)
0.1 mol
5.84 g
250 mL prep (250 mL)
0.25 mol
14.61 g
500 mL prep (500 mL)
0.5 mol
29.22 g
1 L prep (1 L)
1 mol
58.44 g
Volume equivalents
Unit
Value
L
1 L
mL
1,000 mL
uL
1,000,000 uL
dL
10 dL
Mass equivalents
Unit
Value
g
58.44 g
mg
58,440 mg
kg
0.06 kg
Molarity is based on final solution volume Molarity uses the final solution volume, not the solvent volume alone. In practice, dissolve the solute in less than the final volume first, then make the solution up to the calibration mark. Temperature, density, and non-ideal mixing can still push real lab concentrations away from a simple classroom estimate.
Molarity calculator guide: mol/L, moles, volume, and mass from solution concentration
Molarity, often written as M, is the most common way chemists express solution concentration: moles of solute per litre of solution. It appears in stoichiometry calculations, buffer preparation, titration work, dilution planning, and pharmaceutical formulation. This calculator solves for molarity, moles, volume, or mass when the other values are known, and it shows the result in familiar lab units such as M, mM, μM, and nM.
M = n/V — the molarity equation
The core relationship is M = n/V, where M is molarity, n is the amount of solute in moles, and V is the final solution volume in litres. That means a 1.0 M solution contains 1 mole of solute in every litre of finished solution, not in every litre of solvent alone.
The calculator handles the common rearrangements as well: n = MV, V = n/M, and m = n × Mw when molar mass is supplied. That makes it useful whether you are starting from moles, a target concentration, or a weighed-out mass.
M = n / V
Molarity is moles of solute per litre of final solution.
n = M × V
Use this rearrangement when concentration and volume are known and you need moles.
m = n × Mw
Convert moles into mass when you know the compound's molar mass.
How to calculate molarity from mass and molar mass
If you know the mass of solute, first convert that mass into moles by dividing by the compound's molar mass, then divide by the final solution volume. For example, 10 g of NaCl in 500 mL of solution gives 10 ÷ 58.44 = 0.171 mol, and 0.171 ÷ 0.5 = 0.342 M.
That is why the page includes a molar-mass field and a mass output. It matches the most common search intent around molarity from mass, grams to moles, and how much solute is needed to make a specific solution strength.
Worked example: preparing 500 mL of 0.1 M sodium chloride
Suppose you want 500 mL of a 0.1 M NaCl solution. Start by converting the target volume into litres: 500 mL = 0.5 L. Then calculate the required moles: n = M × V = 0.1 × 0.5 = 0.05 mol.
Next convert moles into mass using NaCl's molar mass of 58.44 g/mol. Mass = 0.05 × 58.44 = 2.922 g. In practice, weigh 2.922 g of NaCl, dissolve it in less than 500 mL of water, then top the flask up to the final 500 mL mark so the finished solution has the target molarity.
How to convert molarity into g/L and mg/mL
A molarity value becomes a mass concentration once you multiply it by the compound's molar mass. The relationship is mass concentration = molarity × molar mass, with the result in g/L when molarity is in mol/L and molar mass is in g/mol.
That is why a page like this needs more than just M, moles, and litres. If a compound has a molar mass of 180.16 g/mol, then a 10 mM solution is 0.010 mol/L × 180.16 g/mol = 1.8016 g/L, which is also 1.8016 mg/mL. Those are often the units used in formulation sheets, assay methods, and supplier documents.
mass concentration (g/L) = M × Mw
Convert molarity into grams per litre when the molar mass is known.
mg/mL = g/L
The numerical value in g/L is the same as mg/mL because both are 1000-fold conversions in numerator and denominator.
A practical lab-preparation workflow
For real solution preparation, do not pour solvent straight to the final line before adding the solute. The correct workflow is to weigh or measure the solute, dissolve it in less than the target final volume, then transfer and bring the mixture up to the final calibration mark.
That distinction matters because molarity is defined with respect to the final solution volume. If you start with 1 L of solvent and then add solid solute, the finished solution may occupy more than 1 L, and the true molarity will be lower than the classroom estimate unless you make the final volume up accurately.
When molarity is the right concentration scale
Molarity is the usual choice for stoichiometry, titration preparation, and many aqueous bench solutions because reactions depend on moles, not just mass. It is also convenient for serial dilution planning because the amount-of-substance basis remains explicit.
It is less ideal when temperature-driven volume changes matter, or when your protocol is defined by mass fraction, density, or osmolality instead of moles per litre. In those cases, molality, percent concentration, or density-based concentration measures may be the more defensible choice.
Molarity depends on the final solution volume, so it can shift slightly with temperature if the solution expands or contracts. Molality, by contrast, is moles per kilogram of solvent and is temperature-stable, which is why it is often preferred for some physical-chemistry calculations.
The SI sources also prefer the term amount-of-substance concentration over molarity, but molarity remains the search term and lab shorthand most people use. This page keeps the familiar M label while also clarifying the more exact terminology.
Further reading
NIST Guide to the SI, Chapter 8 — Official NIST guidance for amount-of-substance concentration, molarity terminology, and SI unit conventions.
IUPAC Green Book PDF — IUPAC reference covering amount concentration, molarity terminology, and the distinction from molality.
Frequently asked questions
What is the formula for molarity?
The formula is M = n/V, where M is molarity, n is moles of solute, and V is the final solution volume in litres.
How do I calculate molarity from mass?
Divide the solute mass by its molar mass to get moles, then divide by the final solution volume in litres. The calculator does that conversion automatically when you enter a molar mass.
What is the difference between molarity and molality?
Molarity is moles per litre of solution, so it depends on volume. Molality is moles per kilogram of solvent, so it does not change with temperature in the same way.
Why does the calculator support mM, μM, and nM?
Many chemistry, biology, and drug-concentration problems use smaller concentration scales than 1 M. Supporting millimolar, micromolar, and nanomolar units makes the result easier to read in the units scientists actually use.
Why does molarity use the final solution volume instead of solvent volume?
Molarity is defined as moles of solute per litre of final solution, so the completed volume matters. That is why you dissolve the solute first and then top up to the target volume rather than measuring only the starting solvent.
How do I convert molarity to g/L or mg/mL?
Multiply the molarity by the compound's molar mass. A concentration in mol/L times a molar mass in g/mol gives g/L. The same numerical value can also be read as mg/mL, which is why formulation sheets often switch between those two unit styles once molar mass is known.
What does 1 M mean in practical bench terms?
A 1 M solution contains 1 mole of solute in each litre of final solution. That also means 1 mmol per mL and 1 μmol per μL, which is why 1 M is often a convenient reference point when scaling aliquots and serial dilutions.
Can I calculate molarity if I only know grams and volume?
Yes, but only if you also know the compound's molar mass. First convert grams to moles using moles = mass ÷ molar mass, then divide those moles by the final solution volume in litres.
Does temperature change molarity?
It can. Molarity depends on the final solution volume, and liquids expand or contract with temperature. For ordinary classroom problems the effect is usually ignored, but for tighter laboratory work the solution should be prepared and measured at the temperature assumed by the protocol.
When should I use a dilution calculator instead of a molarity calculator?
Use a molarity calculator when you are moving between moles, mass, volume, and concentration for one solution state. Use a dilution calculator when you already have a stock concentration and need to work out the transfer volume or final volume for a weaker working solution of the same solute.
