Dilution Calculator
Solve C1V1 = C2V2, work out dilution ratios, and plan serial dilution series.
Stock & final concentration (C₁V₁ = C₂V₂)
Enter any three values and clear the fourth (leave it blank) to solve for it. C₁ and C₂ must use the same kind of unit — both molar, or both mass/percent — to convert correctly.
Dilution factor / ratio
Work out volumes for a ratio like 1:10 (1 part stock, 9 parts diluent, 10 parts total).
Serial dilution series
How dilution calculations work
C₁V₁ = C₂V₂ is the core dilution equation: the amount of solute in your stock (concentration × volume) stays the same after you dilute it, it's just spread through more liquid. So if you know any three of stock concentration, stock volume, final concentration and final volume, you can solve the fourth. Example: diluting a 10 mM stock down to 1 mM in a final volume of 100 µL needs V₁ = C₂V₂/C₁ = (1 × 100) / 10 = 10 µL of stock, topped up with 90 µL of diluent.
Dilution ratio and factor: a 1:10 dilution means 1 part stock combined with enough diluent to reach 10 total parts (so 9 parts diluent). The dilution factor is the total parts divided by the stock parts — 1:10 is a 10-fold dilution, meaning the concentration drops to 1/10th. If you also enter a starting concentration, the tool multiplies it by (stock parts ÷ total parts) to show the resulting concentration.
Serial dilutions repeat the same dilution factor across a chain of tubes: each tube already holds diluent, and you transfer a fixed volume from the previous tube into it. For a 2-fold series with 200 µL tubes, each tube holds 100 µL diluent and you transfer 100 µL from the tube before it (100/200 = the 1/factor fraction), so the concentration halves at every step: 100, 50, 25, 12.5 µM and so on.
Tips: molar units (M, mM, µM, nM) and mass/percent units (mg/mL, µg/mL, %) are different physical quantities — converting between them needs the solute's molecular weight, so this calculator only converts within the same family and will warn you if C₁ and C₂ don't match. "X" units (like 10X buffer) are treated as a plain multiplier. Always vortex or mix thoroughly between serial dilution steps, since small pipetting errors compound at every step of the series.
Dilution Calculator: frequently asked questions
What is the C1V1 = C2V2 formula?
It is the dilution equation: the concentration of your stock (C1) times the volume of stock you use (V1) equals the final concentration (C2) times the final total volume (V2). Because the amount of solute does not change on dilution, knowing any three values lets you solve the fourth.
How much stock and diluent do I need for a 1:10 dilution?
A 1:10 dilution means 1 part stock in a total of 10 parts. For a 10 mL final volume, use 1 mL of stock and add 9 mL of diluent (1 mL + 9 mL = 10 mL total, a 10-fold dilution).
Why can't I mix molar and percent units?
Molar units (M, mM, µM, nM) measure moles per litre, while % and mg/mL measure mass per volume. Converting between them requires the molecular weight of the solute, so this calculator only converts within the same family — pick matching unit types for both concentrations.
How does a serial dilution work?
In a serial dilution you dilute by the same factor at each step, transferring a fixed volume from one tube into the next tube of diluent. The calculator shows the concentration at every step along with the diluent already in each tube and the volume to transfer in.
What is the difference between dilution factor and dilution ratio?
A dilution ratio like 1:10 describes parts of stock to total parts. The dilution factor is the total divided by the stock parts (so 1:10 is a 10-fold, or 10x, dilution) — it tells you how many times the concentration has been reduced.