Concentration Calculator
Use this tool to calculate molarity, dilution, or required solute mass for your solution prep.
Enter any three values and leave exactly one blank. Use consistent volume units (both mL or both L).
What is concentration?
Concentration tells you how much solute is present in a given amount of solution. In chemistry, biology, medicine, and environmental work, concentration is one of the most common values you calculate before running any experiment or preparing any stock solution.
If your concentration is wrong, your reaction rate, pH behavior, assay response, or dosage can be off. That is why a fast, reliable concentration calculator is useful for both students and professionals.
What this concentration calculator can do
1) Molarity from mass
Use this mode when you know how many grams of compound you weighed, the compound's molar mass, and your final solution volume.
- Converts mass to moles
- Divides by total solution volume in liters
- Returns molarity (M), millimolar (mM), and mass concentration (g/L)
2) Dilution using C1V1 = C2V2
Use this mode to prepare a weaker solution from a stronger stock. Enter three values and leave one field blank to solve for the unknown.
- Find how much stock to pipette (V1)
- Find the final concentration after dilution (C2)
- Find required final volume (V2)
3) Mass required for a target molarity
Use this mode before you weigh your chemical. Enter desired molarity, final volume, and molar mass to get the grams needed.
Core formulas used
- Molarity: M = n / V
- Moles from mass: n = m / MM
- Combined: M = m / (MM × V)
- Dilution: C1V1 = C2V2
- Mass needed: m = M × V × MM
Worked examples
Example A: NaCl molarity
Suppose you dissolve 5.84 g NaCl (58.44 g/mol) to make 0.500 L solution:
- Moles = 5.84 / 58.44 = 0.0999 mol
- Molarity = 0.0999 / 0.500 = 0.1998 M
- About 0.200 M
Example B: Diluting stock acid
You have 1.0 M stock and need 250 mL of 0.10 M:
- V1 = (C2 × V2) / C1 = (0.10 × 250) / 1.0 = 25 mL
- Pipette 25 mL stock, then dilute to 250 mL total volume
Example C: Glucose solution prep
You want 1.00 L of 0.250 M glucose (MM = 180.16 g/mol):
- m = M × V × MM = 0.250 × 1.00 × 180.16 = 45.04 g
- Weigh 45.04 g glucose and make to 1.00 L
Common concentration units you should know
- M (mol/L): Moles per liter; most common in general chemistry.
- mM (mmol/L): 1/1000 of a molar, often used in biochemistry.
- g/L: Grams of solute per liter of solution.
- % w/v: Grams per 100 mL solution (common in biology labs).
- ppm: Parts per million, often used in environmental analysis.
Tips for accurate concentration calculations
- Always verify molar mass from a trusted source.
- Use liters for molarity calculations unless your formula accounts for mL conversion.
- For dilution, keep volume units consistent on both sides of C1V1 = C2V2.
- Record significant figures based on your measurement precision.
- Mix thoroughly after making up final volume.
Frequently asked questions
Can I use mL in dilution mode?
Yes. You can use mL or L, as long as V1 and V2 are in the same unit.
Do I enter solvent volume or final solution volume?
Use final solution volume for molarity formulas. In practice, dissolve first, then bring to final mark.
What if my value is very small or very large?
The calculator automatically formats values and may display scientific notation when needed.
Final note
This concentration calculator is a practical helper for quick checks, lab prep, class assignments, and day-to-day problem solving. For regulated or high-stakes work, always confirm calculations with your lab SOP and independent verification.