Dilution Calculator
Calculate stock solution volume, diluent volume, final volume, or concentration using the standard dilution equation.
Calculator is for informational purposes only. Terms and Conditions
Choose what to solve for
Select the unknown dilution variable. The required fields update automatically.
Enter the known values
Use compatible concentration units for C1 and C2, then select the result unit in advanced options.
Visual Check
The diagram shows stock solution plus diluent making the final diluted solution.
Solution
Live result, quick checks, warnings, and solution steps.
Quick checks
- Diluent needed—
Show solution steps See the equation, substitutions, assumptions, and result path
- Enter values to see the full calculation steps and checks.
Source, Standards, and Assumptions
Calculation basis, constants, assumptions, and limitations.
Uses the standard solution dilution relationship C1V1 = C2V2 for ideal mixing.
- Assumptions will appear after a valid calculation.
On this page
Calculator Guide
How to Use the Dilution Calculator
The Dilution Calculator above helps you solve \(C_1V_1=C_2V_2\), find the stock solution volume, and calculate how much diluent to add. As a solution dilution calculator, it is most useful when you know the stock concentration, target concentration, and final volume.
Use the guide below to understand the formula, check your units, avoid common dilution mistakes, and verify the result with worked examples. For normal solution preparation, the key idea is simple: calculate the stock volume first, then add diluent until the final total volume is reached.
Quick Answer
To calculate a dilution, use \(V_1=\frac{C_2V_2}{C_1}\). After finding the stock volume \(V_1\), calculate the diluent as \(V_2-V_1\). For example, making \(250\,mL\) of \(1\,mM\) solution from a \(10\,mM\) stock requires \(25\,mL\) of stock and enough diluent to reach \(250\,mL\) total volume.
Common dilution examples this page helps with
Typical dilution problems include \(10\,mM\) to \(1\,mM\), \(10X\) stock to \(1X\), \(95\%\) ethanol to \(70\%\), and 1:10 or 1:100 ratio dilutions.
When not to rely on a simplified dilution result
Do not use a basic dilution calculation as the only safety check for hazardous chemicals, biological materials, reactive mixtures, or regulated processes. Follow the product SDS, lab procedures, and applicable safety requirements.
Inputs and Outputs Used by the Dilution Calculator
The dilution calculator uses the same four variables in the standard dilution formula. Depending on the selected solve mode, one variable is unknown and the other three are entered as known values.
| Value | Meaning | Common Units | Typical Use |
|---|---|---|---|
| \(C_1\) | Stock concentration before dilution | M, mM, µM, mg/mL, %, ppm, X | The strength of the starting solution |
| \(V_1\) | Stock volume to use | µL, mL, L, fl oz, gal | The amount of stock solution added |
| \(C_2\) | Final concentration after dilution | M, mM, µM, mg/mL, %, ppm, X | The target working concentration |
| \(V_2\) | Final total solution volume | µL, mL, L, fl oz, gal | The final volume after stock plus diluent |
| Diluent | Solvent, water, buffer, or carrier added to reach final volume | Same volume unit as \(V_2\) | Calculated as \(V_2-V_1\) |
Dilution Formula Used by the Calculator
The dilution formula is based on conservation of solute. Dilution changes the volume and concentration, but the amount of dissolved solute stays the same if no reaction, loss, or concentration step occurs.
Main Formula
This is the formula behind most solution dilution calculations. It works when \(C_1\) and \(C_2\) are compatible concentration units and \(V_1\) and \(V_2\) are compatible volume units.
Common Rearrangements
The most common solve mode is \(V_1\), which tells you how much stock solution to use.
How Much Water or Diluent Do I Add?
If \(V_2\) is the final total volume and \(V_1\) is the stock volume, the diluent is the difference. In accurate lab preparation, add stock first, then add diluent until the total solution reaches the final volume mark.
What the Variables Mean
Each dilution variable describes either the starting stock condition or the final diluted condition. The subscripts help keep the workflow organized: “1” means before dilution, and “2” means after dilution.
\(C_1\): Stock concentration
The concentration of the starting solution. It must be greater than or equal to \(C_2\) for a true dilution.
\(V_1\): Stock volume
The volume of stock solution needed. This is usually the main answer users want from a dilution calculator.
\(C_2\): Final concentration
The desired working concentration after dilution. It must use a compatible unit family with \(C_1\).
\(V_2\): Final volume
The total volume of the diluted solution, not just the amount of water, buffer, or solvent added.
How to Use the Dilution Calculator
Start with the solve mode that matches your unknown value. Most users choose stock volume \(V_1\), but the same formula can also solve for final volume, stock concentration, or final concentration.
Select the solve mode
Choose whether you want to calculate \(V_1\), \(V_2\), \(C_1\), or \(C_2\). For normal solution preparation, choose stock volume needed.
Enter compatible concentrations
Use compatible concentration units, such as mM to mM, µM to mM, mg/mL to µg/mL, percent to percent, or X stock to X working solution.
Enter the final volume
Use the total final volume you want to prepare, not the amount of diluent. The calculator will calculate the diluent separately.
Check the answer
Review stock volume, diluent volume, dilution factor, and solution steps. If \(C_2\) is higher than \(C_1\), the problem is not a true dilution.
How to Interpret Dilution Results
A dilution result tells you how much stock solution contributes to the final mixture. A smaller \(C_2/C_1\) ratio means less stock and more diluent are needed.
What to do with the result
Measure the calculated stock volume, transfer it to the container, then add diluent until the final total volume is reached.
What changes the result most?
The concentration ratio controls the answer. A 10-fold dilution uses 10% stock, while a 100-fold dilution uses 1% stock.
Sanity check
For a true dilution, \(V_1\) should be less than \(V_2\), the diluent should be positive, and \(C_2\) should be lower than \(C_1\).
Input Checklist Before You Trust the Answer
Most dilution errors come from entering the right number with the wrong unit or confusing final volume with diluent volume.
- Confirm \(C_1\) is the stock concentration, not the target final concentration.
- Confirm \(V_2\) is the final total volume, not the volume of water or buffer alone.
- Use compatible concentration units for \(C_1\) and \(C_2\).
- Convert µL, mL, and L consistently if doing the calculation by hand.
- Check that the calculated stock volume is practical to measure with your pipette, syringe, or graduated container.
- For hazardous chemicals, verify handling instructions with the product SDS before preparing the solution.
Worked Example
This example matches the most common search intent: finding how much stock solution to use and how much diluent to add.
Formula
Substitution
Diluent calculation
Final answer
Use 25 mL of 10 mM stock solution, then add diluent until the total final volume is 250 mL. The required diluent amount is 225 mL if volumes are treated as additive.
Reverse check
The stock is 10 times stronger than the final solution, so the stock should be one-tenth of the final volume. One-tenth of \(250\,mL\) is \(25\,mL\), so the result is reasonable.
Stock volume
Diluent amount
Percent dilution result
Use 368.42 mL of 95% stock, then add diluent until the final solution volume is 500 mL. This example is useful for percent solution dilution, such as ethanol or other concentration-by-percent mixtures.
What the Dilution Formula Represents
The formula says the amount of solute before dilution equals the amount of solute after dilution. The stock solution contributes solute, and the diluent increases volume while lowering concentration.
The stock side represents \(C_1\) and \(V_1\), while the final side represents \(C_2\) and \(V_2\). The calculator finds the stock portion first, then uses the final volume to determine the amount of diluent needed.
Reference Checks for Common Dilutions
Dilution calculations do not have universal “good” reference values because the right answer depends on the stock concentration and target solution. Instead, use common dilution factors as reasonableness checks.
| Dilution Factor | Stock Fraction | Typical Ratio Interpretation | Example for 1 mL Final Volume |
|---|---|---|---|
| 2× | 50% | 1 part stock + 1 part diluent | 500 µL stock + 500 µL diluent |
| 10× | 10% | 1 part stock in 10 total parts | 100 µL stock + 900 µL diluent |
| 100× | 1% | 1 part stock in 100 total parts | 10 µL stock + 990 µL diluent |
Source note
For a general chemistry explanation of dilution and the relationship between initial and final concentration, see the Khan Academy dilution lesson.
Practical Lab Notes and Range Checks
Dilution math is simple, but practical preparation still depends on measurement accuracy. Very small stock volumes, very large dilution factors, or hazardous materials may require a different workflow.
Small stock volumes
If the stock volume is below what your pipette or measuring device can reliably measure, prepare an intermediate dilution first.
Large dilution factors
A 1:1,000 or 1:1,000,000 dilution is often more practical as a serial dilution than a single-step dilution.
Final volume matters
For accurate lab preparation, add diluent to the final volume mark rather than assuming every added volume behaves perfectly.
Safety matters
When diluting acids, bases, solvents, or hazardous reagents, follow the SDS and established lab procedure.
Units and Conversions
The calculator can handle common concentration and volume units, but the key rule is compatibility. You can convert within the same concentration family, but not between unrelated families without more information.
Molarity units
M, mM, µM, nM, and pM are compatible because they all measure molar concentration.
Mass-per-volume units
mg/mL, µg/mL, ng/µL, and g/L are compatible mass concentration units.
Percent and trace units
Percent, ppm, and ppb can be used carefully when the same concentration convention is being applied. Exact ppm or ppb interpretation may depend on whether the concentration is mass/mass, mass/volume, or volume/volume.
Molarity to mass concentration
Converting mM to mg/mL requires molecular weight. Use a molarity calculator when mass, moles, and solution volume are part of the problem.
Common unit trap
\(1\,mL=1000\,\mu L\). If your hand calculation gives a stock volume in mL but your pipette is in µL, convert before measuring.
Dilution Factor vs Dilution Ratio
Dilution factor and dilution ratio are related, but users often confuse the wording. A 10-fold dilution means the final volume is 10 times the stock volume. A 1:10 dilution is commonly interpreted as 1 part stock in 10 total parts.
10-fold dilution
- Final concentration is one-tenth of stock concentration.
- Stock volume is one-tenth of final volume.
- For 1 mL final volume, use 100 µL stock and 900 µL diluent.
Common mistake
- Do not treat 1:10 as 1 part stock plus 10 parts diluent unless your procedure specifically defines it that way.
- Do not use dilution ratio language without confirming whether the final total volume or added diluent is being described.
Common Dilution Mistakes
The formula is simple, but small wording and unit mistakes can change the answer by 10×, 100×, or more.
Do
- Use final total volume for \(V_2\).
- Calculate diluent as \(V_2-V_1\).
- Keep \(C_1\) and \(C_2\) in compatible unit families.
- Reverse-check the answer using \(C_1V_1=C_2V_2\).
Don’t
- Do not enter diluent volume as final volume.
- Do not dilute to a concentration higher than the stock concentration.
- Do not convert mM to mg/mL without molecular weight.
- Do not ignore impractically small stock volumes.
Troubleshooting Unrealistic Dilution Results
If the result looks wrong, check the concentration order, unit family, final volume definition, and whether the problem is truly a dilution.
Stock volume is larger than final volume
This usually means \(C_2\) is greater than \(C_1\), or the concentrations were entered in reversed order.
Diluent is negative
A negative diluent volume means the entered values do not describe a normal dilution.
Stock volume is tiny
If the result is only a fraction of a microliter, use an intermediate dilution or a serial dilution workflow.
Answer is off by 1000×
Check whether mL and µL, M and mM, or mg/mL and µg/mL were mixed without conversion.
Assumptions and Limitations
The dilution calculator assumes the solute amount is conserved and the selected concentration units describe the same kind of concentration. It is an educational and planning tool, not a substitute for lab safety review.
Solute is conserved
The formula assumes no solute is lost, consumed, precipitated, evaporated, or chemically changed during dilution.
Ideal mixing
The calculation assumes the final solution can be represented by a single uniform concentration.
Compatible units
The calculator can dilute mM to µM or mg/mL to µg/mL, but molarity-to-mass conversions require molecular weight.
Safety review
For acids, bases, solvents, biological materials, and hazardous reagents, follow SDS guidance and lab procedures.
Key Dilution Terms
These terms help connect the calculator inputs, formula, and result interpretation.
Stock solution
A concentrated starting solution used to prepare a lower-concentration working solution.
Diluent
The water, buffer, solvent, or carrier added to reduce concentration and reach the final volume.
Dilution factor
The ratio \(C_1/C_2\) or \(V_2/V_1\). A 10× dilution has a dilution factor of 10.
Final volume
The total volume after stock and diluent are combined. It is not always the same as the amount of diluent added.
FAQ
What is the dilution formula?
The standard dilution formula is \(C_1V_1=C_2V_2\), where \(C_1\) is the stock concentration, \(V_1\) is the stock volume, \(C_2\) is the final concentration, and \(V_2\) is the final volume.
How do I calculate how much diluent to add?
First calculate the stock volume using \(V_1=\frac{C_2V_2}{C_1}\). Then subtract the stock volume from the final volume: \(V_{\text{diluent}}=V_2-V_1\).
Is a 1:10 dilution the same as a 10-fold dilution?
In most lab contexts, yes. A 1:10 dilution usually means 1 part stock in 10 total parts, which is 1 part stock plus 9 parts diluent.
Can I use percent or mg/mL units in a dilution calculation?
Yes, if \(C_1\) and \(C_2\) use compatible concentration units. Percent can be diluted to percent, and mg/mL can be diluted to mg/mL or another mass-per-volume unit.
What if the final concentration is higher than the stock concentration?
That is not a true dilution. A final concentration higher than the stock concentration requires concentrating the solution, adding solute, evaporating solvent, or using a stronger stock.
Why is my dilution result negative or impossible?
A negative diluent volume or dilution factor below 1 usually means the final concentration is higher than the stock concentration. That is mathematically possible as a rearranged equation, but it is not a true dilution.