Dilution Calculator (C1V1 = C2V2)
Enter any three values and leave one blank. The calculator will solve for the missing concentration or volume.
Use consistent units (for example: mg/mL for concentration and mL for volume).
What is a dilution concentration calculator?
A dilution concentration calculator helps you prepare a weaker solution from a stronger stock solution. In chemistry, biology, pharmacy, and environmental testing, this calculation is used constantly: you know a stock concentration and need to create a target concentration at a target volume.
Instead of doing repeated manual algebra, this tool solves the standard dilution equation quickly and shows you useful outputs such as dilution factor and how much solvent to add.
The core dilution equation
The relationship is:
- C1 = initial (stock) concentration
- V1 = volume of stock used
- C2 = desired final concentration
- V2 = final total volume after dilution
This equation assumes the amount of solute is conserved during dilution.
How to use this calculator
Step-by-step
- Enter three known values.
- Leave one field blank (the unknown you want to solve).
- Click Calculate.
- Read the result and optional details.
Tip: keep your units consistent. If concentration is in mol/L, keep both concentrations in mol/L. If volume is in mL, keep both volumes in mL.
Worked examples
Example 1: Prepare 100 mL of a 1 mg/mL solution from a 10 mg/mL stock
Given: C1 = 10, C2 = 1, V2 = 100. Solve for V1:
V1 = (C2 × V2) / C1 = (1 × 100) / 10 = 10 mL.
So you need 10 mL stock and then add solvent up to 100 mL total (90 mL solvent).
Example 2: Find the final concentration after dilution
Given: C1 = 5 M, V1 = 20 mL, V2 = 200 mL. Solve for C2:
C2 = (C1 × V1) / V2 = (5 × 20) / 200 = 0.5 M.
Common dilution terms you might search for
- molarity dilution calculator
- stock solution concentration calculator
- serial dilution calculator
- percent dilution formula
- C1V1 C2V2 calculator
- solution preparation calculator
Best practices and common mistakes
1) Unit mismatches
The most common error is mixing units (for example, entering V1 in mL and V2 in L). Convert first.
2) Confusing final volume with solvent volume
V2 is the total final volume, not just added water or buffer.
3) Expecting dilution when concentration actually increases
If C2 is greater than C1, you are concentrating rather than diluting. The equation still works mathematically, but the physical process is different.
Quick FAQ
Can I use this for ppm and ppb?
Yes, if both concentration values are in the same type of unit.
Can I use this for % w/v or % v/v?
Yes, as long as C1 and C2 use the same percent basis and your volumes are consistent.
What if I need serial dilutions?
Use this calculator step-by-step for each stage (for example 1:10, then 1:10 again for a total 1:100).
Bottom line
A reliable dilution calculator concentration tool saves time and prevents lab mistakes. Use the C1V1 = C2V2 relationship, keep units consistent, and double-check whether you are preparing a dilution or a concentration step.