Dilution Calculator

The dilution equation C1V1 = C2V2 relates the concentration and volume of a solution before and after dilution. To dilute 50 mL of a 2.0 M solution to 0.5 M, the final volume is V2 = (2.0 x 50) / 0.5 = 200 mL, meaning 150 mL of solvent must be added. Select which variable to solve for, enter the three known values, and the result appears instantly.

Quick Answer

Diluting 50 mL of a 2.0 M solution to 0.5 M requires a final volume of 200.00 mL (add 150.00 mL of solvent).

Common Examples

Input Result
C1 = 2.0 M, V1 = 50 mL, C2 = 0.5 M V2 = 200.00 mL (add 150.00 mL solvent)
C1 = 6.0 M, V1 = 25 mL, C2 = 1.5 M V2 = 100.00 mL (add 75.00 mL solvent)
C1 = 12.0 M, V1 = 10 mL, V2 = 500 mL C2 = 0.24 M
C2 = 0.1 M, V2 = 250 mL, C1 = 1.0 M V1 = 25.00 mL
V1 = 100 mL, C2 = 0.25 M, V2 = 400 mL C1 = 1.00 M

How It Works

This calculator uses the dilution equation:

C₁V₁ = C₂V₂

Where:

  • C₁ = initial (stock) concentration
  • V₁ = initial volume (amount of stock solution to use)
  • C₂ = final (diluted) concentration
  • V₂ = final total volume after dilution

The equation expresses conservation of solute: the amount of solute (concentration times volume) remains the same before and after dilution. Only the solvent volume changes.

Rearranged Forms

  • V₂ = (C₁ x V₁) / C₂ (find final volume)
  • C₂ = (C₁ x V₁) / V₂ (find final concentration)
  • V₁ = (C₂ x V₂) / C₁ (find initial volume needed)
  • C₁ = (C₂ x V₂) / V₁ (find initial concentration)

Solvent to Add

The amount of solvent (typically water) to add equals V₂ - V₁. This is the difference between the final and initial volumes.

Important Notes

This equation assumes that volumes are additive and that the solute does not significantly affect the total volume. It applies to most dilute aqueous solutions. For very concentrated solutions or solutions involving significant volume changes upon mixing, more precise methods may be needed.

The concentration units must be consistent (both in M, both in % w/v, etc.), and the volume units must also match (both in mL, both in L, etc.).

Worked Example

A laboratory needs to prepare 500 mL of 0.1 M HCl from a stock solution of 12.0 M HCl. How much stock solution is needed?

V₁ = (C₂ x V₂) / C₁ = (0.1 x 500) / 12.0 = 50 / 12 = 4.17 mL

So 4.17 mL of 12.0 M HCl is diluted to a total volume of 500 mL by adding 495.83 mL of water.

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Frequently Asked Questions

What does C1V1 = C2V2 mean?
The equation states that the moles of solute before dilution (C1 times V1) equals the moles of solute after dilution (C2 times V2). Dilution only adds solvent; it does not add or remove solute. So the product of concentration and volume must remain constant.
What units should I use?
The concentration units must match on both sides (e.g., both in mol/L, both in % w/v). The volume units must also match (both in mL or both in L). As long as units are consistent, the equation works. This calculator uses molarity (M) for concentration and milliliters (mL) for volume by convention.
Can I use this for serial dilutions?
Yes. For serial dilutions, apply the C1V1 = C2V2 equation at each step. The final concentration of one step becomes the initial concentration (C1) of the next step. For a 1:10 serial dilution, each step reduces concentration by a factor of 10.
Does this work for diluting household products like bleach?
Yes. If you know the initial concentration (e.g., 5.25% sodium hypochlorite for household bleach) and want a specific final concentration, the C1V1 = C2V2 equation applies. Just keep the concentration units consistent (both as percentages or both as molarities).
What if the final concentration is higher than the initial?
If C2 > C1, the equation would require V2 < V1, which means you would need to remove solvent (concentrate, not dilute). The equation C1V1 = C2V2 technically works mathematically, but the physical process is evaporation or other concentration methods, not simple dilution by adding solvent.