Dilution Calculator (C1V1 = C2V2)
Enter any three values and leave one field blank. The calculator will solve the missing value and show dilution details.
What is dilution?
Dilution is the process of lowering concentration by adding more solvent. In a chemistry lab, this could mean diluting a stock reagent with water or buffer. In biotech, you might dilute a DNA sample before PCR. In day-to-day life, it can be as simple as mixing a strong cleaning concentrate with water at the right ratio.
A reliable dilution calculation prevents waste, improves reproducibility, and keeps experiments or formulations consistent. Instead of guessing volumes, you can use a single equation to get accurate numbers every time.
C1 = starting concentration, V1 = volume of stock solution used, C2 = target concentration, V2 = final total volume.
How to use this dilution calculator
Step-by-step
- Enter values for any three variables: C1, V1, C2, and V2.
- Leave exactly one field blank.
- Type your concentration and volume unit labels (for display clarity).
- Click Calculate.
- Read the solved value, dilution factor, and diluent volume in the result panel.
The calculator is unit-agnostic, meaning it works with any consistent units. For example, if concentration is in mM, both C1 and C2 should be in mM. If volume is in mL, both V1 and V2 should be in mL.
Worked examples
Example 1: Prepare 100 mL of 1 mM from a 10 mM stock
Known values: C1 = 10 mM, C2 = 1 mM, V2 = 100 mL. Unknown: V1.
V1 = (C2 × V2) / C1 = (1 × 100) / 10 = 10 mL.
So you need 10 mL stock and 90 mL diluent.
Example 2: Find final concentration after mixing
Known values: C1 = 5%, V1 = 20 mL, V2 = 100 mL. Unknown: C2.
C2 = (C1 × V1) / V2 = (5 × 20) / 100 = 1%.
Example 3: Solve for final volume
Known values: C1 = 2 mg/mL, V1 = 5 mL, C2 = 0.5 mg/mL. Unknown: V2.
V2 = (C1 × V1) / C2 = (2 × 5) / 0.5 = 20 mL.
Understanding dilution factor and ratio
The dilution factor tells you how many times less concentrated the final solution is compared with the stock:
- Dilution factor = C1 / C2
- A factor of 10 means a tenfold dilution (often written as 1:10).
- For a 1:10 dilution, 1 part stock is mixed with 9 parts solvent.
This matters in protocols that specify fold dilution (2x, 5x, 10x, 100x) rather than direct concentration targets.
Common mistakes to avoid
- Mixing units: combining mL and µL without conversion creates major errors.
- Confusing V1 with diluent volume: V1 is stock volume, not solvent added.
- Using final volume incorrectly: V2 is total final volume after mixing.
- Rounding too early: keep extra digits until the final step for better precision.
- Target concentration higher than stock: this is concentration, not dilution, and may require solvent removal or a stronger stock.
Serial dilution quick guide
When very low concentrations are needed, a single dilution can be impractical. Serial dilution solves this by doing multiple smaller dilution steps. For example, to reach 1:1000, you might run three consecutive 1:10 dilutions.
Why serial dilution is useful
- Improves pipetting accuracy at very small volumes.
- Reduces measurement error compared with one extreme step.
- Common in microbiology, pharmacology, and assay calibration curves.
Practical applications
- Preparing laboratory buffers and reagents.
- Standardizing assay concentrations for ELISA, qPCR, and spectrophotometry.
- Mixing fertilizers, hydroponic nutrients, or cleaning concentrates.
- Creating calibration standards in analytical chemistry.
- Educational use in chemistry and biology training.
Final tips for accurate results
Always label your stock concentration clearly, document each dilution step, and verify unit consistency before mixing. If precision is critical, use calibrated volumetric tools and keep a written record of your dilution plan.
This dilution calculator is designed to be fast and flexible: enter any three values, solve the fourth, and use the output as a clean reference for your workflow.