Dilution Calculator
Enter Your Dilution Values
Fill in three of the four C1V1=C2V2 fields — or switch to Ratio or Serial mode — and results will appear here instantly.
How to Use the Dilution Calculator
Choose Your Mode
Select C1V1=C2V2 for standard lab dilutions, Ratio Mode for cleaning solutions and disinfectants expressed as ratios (e.g., 1:10), or Serial Dilution for planning a dilution series with repeated equal-factor steps.
Select What to Solve For
In C1V1=C2V2 mode, click which of the four variables you want the calculator to find — typically V1 (how much stock to pipette). Enter values and units for the other three fields. The calculator updates results automatically.
Set Concentration and Volume Units
Use the unit dropdowns next to each field to match your lab context. Choose molar units (M, mM, µM, nM) for biochemistry, mass-per-volume units (mg/mL, µg/mL, ng/mL) for protein or drug concentrations, or % v/v for solutions expressed as percentages. Volume units range from nL to L.
Read Preparation Instructions and Export
The results section shows the solved variable prominently, along with stock volume, diluent volume, and dilution factor. Human-readable preparation instructions tell you exactly how to prepare the solution. Use Copy, Export CSV, or Print to save your protocol.
Frequently Asked Questions
What is the C1V1 = C2V2 formula?
C1V1 = C2V2 is the fundamental dilution equation derived from conservation of solute mass. C1 is the concentration of the stock (starting) solution, V1 is the volume of stock taken, C2 is the desired final concentration, and V2 is the total final volume of the diluted solution. Since no solute is added or removed — only solvent is added — the amount of solute (concentration × volume) must be the same before and after dilution. Rearranging gives V1 = (C2 × V2) / C1, which tells you how much concentrated stock to pipette to achieve a given final concentration and volume. This equation is exact under ideal mixing conditions and is used in every branch of science from biochemistry to chemistry to food science.
What is a dilution factor and how do I calculate it?
The dilution factor (DF) is the ratio of the final volume to the initial volume taken from stock: DF = V2 / V1. It equals C1 / C2 (how many times the concentration decreased). A 10× dilution factor means you took one part stock and added nine parts diluent for a total of ten parts. Common notation: 1:10 means one part stock to nine parts diluent (10× dilution factor), while 1:2 means one part stock to one part diluent (2× dilution factor — often called a half dilution). Some sources use 1:10 to mean one part stock in a total of ten parts (also 10× overall), so context matters. Our calculator displays the dilution factor as C1/C2 = V2/V1 and notes it clearly in results.
What is a serial dilution?
A serial dilution is a sequence of equal dilution steps where each step's output becomes the next step's input. For example, a 1:10 serial dilution starting from 1 M gives: Step 1 → 0.1 M, Step 2 → 0.01 M, Step 3 → 0.001 M, and so on. Serial dilutions are used to prepare standard curves for ELISA and spectrophotometry, to enumerate bacteria by plating diluted samples and counting colonies, and to test drug dose-response relationships. The formula is C_k = C0 / (factor^k), where k is the step number and factor is the dilution applied at each step. Small errors in each step are multiplied together across the series, so careful pipetting technique is essential.
Why can the final concentration not be higher than the stock concentration?
The C1V1=C2V2 equation conserves solute mass — dilution can only decrease concentration by spreading the same number of molecules across a larger volume. You cannot make a 10 mg/mL solution from a 1 mg/mL stock simply by diluting: you would need to add more solute or use a more concentrated stock. If the calculator shows a validation error saying the stock concentration must be higher than the desired final concentration, you need to either use a more concentrated stock, or reconsider your target concentration. This is a physical constraint, not a calculator limitation. If you want to make a higher-concentration solution from a lower-concentration one, you would instead concentrate the solution (by evaporation, ultrafiltration, or freeze-drying).
How do I convert between molar and mass-per-volume concentration units?
Molar concentration (molarity) and mass-per-volume concentration require the molecular weight of the solute to interconvert. Moles = mass (g) / molecular weight (g/mol), so Molarity (M) = [mass in grams / molecular weight] / volume in liters. For example, glucose (MW = 180 g/mol) at 1 mg/mL = 1 g/L corresponds to (1 g/L) / (180 g/mol) = 0.00556 mol/L = 5.56 mM. Our calculator handles conversions within molar units (M, mM, µM, nM, pM, fM) and within mass-per-volume units (g/L through ng/µL) automatically. Cross-type conversions between molar and mass-per-volume require molecular weight and are best done separately before entering values.
What is ratio mode and when should I use it?
Ratio mode is for applications where concentrations are specified as volume-to-volume ratios rather than formal concentration units. Common examples include household bleach diluted 1:10 for surface disinfection, cleaning chemicals sold with instructions like 'dilute 1 part concentrate in 32 parts water,' or paint thinners. In ratio mode, enter the number of parts concentrate (solute), the number of parts diluent (solvent), and the total volume you want to prepare. The calculator tells you exactly how much concentrate and how much diluent to measure out. For instance, a 1:9 ratio in 500 mL total gives 50 mL concentrate + 450 mL diluent. This is equivalent to a 10× dilution or a 10% (v/v) solution.