Last updated: July 3, 2026
Concentration Calculator
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Quick Answer
The concentration calculator computes mass/volume concentration using c = m/V, with mass converted to grams and volume converted to litres. It can also solve m = cV or V = m/c, report equivalents in mg/mL, % (m/v), ppm, and convert to molarity when molar mass is supplied.
Mass concentration equals the mass of solute in grams divided by the final solution volume in litres. For example, ten grams in two litres is five grams per litre.
Key Takeaways
- Mass/volume concentration is c = mass of solute ÷ final solution volume.
- This calculator normalizes grams/milligrams and litres/millilitres before calculating.
- 1 g/L equals 1 mg/mL and 1000 mg/L; in dilute water, that is approximately 1000 ppm.
- Percent (m/v) equals g/L divided by 10 because it is grams per 100 mL.
- If molar mass is supplied, molarity equals g/L divided by g/mol.
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Formula
c = m / V; m = c × V; V = m / c; M = c / molar mass
Where:
- c=Mass concentration(g/L)
- m=Mass of solute(g)
- V=Volume of solution(L)
- M_w=Molar mass of solute(g/mol)
- C=Molarity (amount concentration)(mol/L)
Worked Examples
10 g dissolved to 2 L
A primary mass/volume calculation for a general aqueous solution.
- 1Convert units: mass = 10 g and volume = 2 L.
- 2Apply c = m / V = 10 g ÷ 2 L.
- 3The mass concentration is 5 g/L.
5 g in 500 mL
Millilitre volumes are converted to litres before division.
- 1Convert 500 mL to 0.5 L.
- 2Apply c = 5 g ÷ 0.5 L.
- 3The concentration is 10 g/L, which is also 10 mg/mL.
200 mg in 1 L
A dilute solution expressed in g/L, mg/L, and ppm.
- 1Convert 200 mg to 0.2 g.
- 2Apply c = 0.2 g ÷ 1 L = 0.2 g/L.
- 3Convert to mg/L: 0.2 g/L × 1000 = 200 mg/L ≈ 200 ppm in water.
Mass needed for 5 g/L over 2 L
Solve for the amount of solute required to prepare a target concentration.
- 1Use m = c × V.
- 2Substitute c = 5 g/L and V = 2 L.
- 3m = 5 × 2 = 10 g of solute.
NaCl solution with molarity reported
When molar mass is provided, the calculator also converts mass concentration to molarity.
- 1Mass concentration: c = 5.844 g ÷ 1 L = 5.844 g/L.
- 2Moles per litre = (5.844 g/L) ÷ 58.44 g/mol.
- 3The molarity is 0.1 mol/L.
Introduction
This concentration calculator focuses on mass/volume concentration: grams of solute per litre of final solution. It is designed for general solutions where you know a mass and a final volume, or where you need to prepare a target concentration. It also converts the same result to mg/mL, percent mass/volume, and ppm, and can report molarity when you provide a molar mass. The mass-concentration convention follows IUPAC quantity and SI unit guidance for concentration reporting and unit conversion.
What is mass/volume concentration?
Mass/volume concentration tells you how much solute mass is present in each unit of final solution volume. In this calculator the primary unit is g/L. A value of 5 g/L means every litre of solution contains 5 grams of dissolved solute, assuming the solution is homogeneous.
Use the final solution volume, not the amount of solvent poured first.
Mass concentration is convenient when recipes are weighed on a balance.
It is different from molarity, which counts moles rather than grams.
For dilute aqueous solutions, mg/L is often numerically equal to ppm.
Formula and unit conversions
The core formula is c = m / V, where c is in g/L, m is mass in grams, and V is volume in litres. The calculator converts milligrams to grams and millilitres to litres before calculating. It also reports mg/mL, percent (m/v), and ppm so the same solution can be described in common laboratory and environmental units.
| Unit | Conversion from g/L | Example for 5 g/L |
|---|---|---|
| mg/mL | same numeric value | 5 mg/mL |
| mg/L | multiply by 1000 | 5000 mg/L |
| ppm in dilute water | approximately mg/L | ≈ 5000 ppm |
| % (m/v) | divide by 10 | 0.5 % (m/v) |
Solving for mass of solute
To prepare a target concentration, rearrange the formula to m = c × V. If you want 2 L of a 5 g/L solution, weigh 10 g of solute, dissolve it in less than the final volume, then top up to exactly 2 L. This workflow is also useful before a bleach dilution or buffer preparation step.
Top up to the calibration mark after the solute dissolves; solids and liquids can change the final volume.
Solving for final solution volume
When mass and target concentration are fixed, use V = m / c. For example, 2.5 g at a target of 5 g/L should be diluted to 0.5 L. This is the inverse of the preparation calculation and is helpful when scaling stock recipes or checking whether a weighed sample can make enough solution for an assay.
Concentration vs. molarity
Mass concentration and molarity answer related but different questions. g/L tells you how many grams are present; mol/L tells you how many chemical formula units or molecules are present. To convert g/L to mol/L, divide by molar mass in g/mol. For example, 5.844 g/L NaCl divided by 58.44 g/mol gives 0.1 mol/L. See the Beer-Lambert law calculator for an application where concentration units must match the absorptivity unit.
If two solutes have the same g/L but different molar masses, they do not have the same molarity.
Practical accuracy and reporting
Accurate concentration work depends on balance precision, volumetric glassware, temperature, and complete dissolution. Report enough significant figures to match your least precise measurement. For regulatory or analytical work, follow method-specific guidance such as EPA water monitoring methods and SI reporting principles from the BIPM SI Brochure.
Use clean volumetric flasks or cylinders for final volume.
Record whether ppm is used as mg/L in water or as a true mass fraction.
Account for hydrates when weighing salts.
Label prepared solutions with concentration, solute identity, date, and preparer.
Common applications
Mass/volume concentration appears in reagent labels, environmental reports, cleaning solutions, nutrition solutions, and teaching laboratories. The same formula supports broad calculations without requiring a chemical formula. If you later need acid-base behavior, use concentration with the buffer pH calculator or pKa data, as long as all units are consistent.
| Application | Typical unit | Why it is used |
|---|---|---|
| Reagent preparation | g/L | Directly weighable recipe |
| Water quality | mg/L or ppm | Convenient for trace levels |
| Clinical/biological media | % (m/v) or g/L | Recipe and osmotic checks |
| Spectrophotometry | g/L or mol/L | Depends on calibration model |
Quick Reference Card
Concentration — Quick Reference
Quick reference • Concentration Calculator
c = m / V; m = c × V; V = m / cValid range: Greater than 0 up to the solubility or formulation limit; common lab values span µg/L to hundreds of g/L
Common Values
⚠ Watch Out
- •Use final solution volume, not initial solvent volume.
- •Convert mL to L and mg to g before applying c = m/V.
- •ppm ≈ mg/L is only a dilute aqueous approximation.
- •Hydrated salts require the hydrate molar mass when converting to molarity.
- •Do not exceed solubility; undissolved solid invalidates the concentration.
Pro Tips
- →Dissolve solute first, then top up to the final mark in a volumetric flask.
- →Label every solution with solute, concentration, units, date, and initials.
- →Use g/L for balance-based recipes and mol/L for reaction stoichiometry.
- →Keep significant figures consistent with the balance and glassware tolerances.
- →For serial dilutions, combine this result with dilution-factor calculations.
FAQs
How do I calculate concentration in g/L?
Convert the solute mass to grams and the final solution volume to litres, then divide mass by volume: concentration = mass ÷ volume. For 10 g in 2 L, c = 10 ÷ 2 = 5 g/L.
Is g/L the same as mg/mL?
Yes, the numeric value is the same because 1 g equals 1000 mg and 1 L equals 1000 mL. Therefore 5 g/L equals 5 mg/mL.
How do I convert g/L to percent (m/v)?
Percent (m/v) means grams per 100 mL of solution. Since 1 L is 1000 mL, divide g/L by 10. A 10 g/L solution is 1 % (m/v).
When can mg/L be treated as ppm?
For dilute aqueous solutions, 1 mg/L is approximately 1 ppm because 1 L of water has a mass close to 1 kg. For concentrated solutions or non-water solvents, ppm should be treated as a mass fraction instead.
How is mass concentration different from molarity?
Mass concentration uses grams per litre, while molarity uses moles per litre. Convert g/L to mol/L by dividing by the solute molar mass in g/mol.
Why should I use final solution volume?
Concentration is defined per volume of solution after the solute is dissolved and the mixture is brought to volume. Using the starting solvent volume can give the wrong concentration if volume changes during dissolution.