Dilution Calculator

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Dilution Calculator (C1V1 = C2V2)
Final Concentration (C2)Volume of Stock Needed (V1)Final Volume Needed (V2)Initial Concentration (C1)
Result:
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function updateInputs(){var type=document.getElementById('calc_type').value;var l1=document.getElementById('label1');var l2=document.getElementById('label2');var l3=document.getElementById('label3′);if(type=='C2′){l1.innerHTML='Initial Concentration (C1):';l2.innerHTML='Initial Volume (V1):';l3.innerHTML='Final Volume (V2):';}else if(type=='V1′){l1.innerHTML='Initial Concentration (C1):';l2.innerHTML='Final Concentration (C2):';l3.innerHTML='Final Volume (V2):';}else if(type=='V2′){l1.innerHTML='Initial Concentration (C1):';l2.innerHTML='Initial Volume (V1):';l3.innerHTML='Final Concentration (C2):';}else if(type=='C1′){l1.innerHTML='Initial Volume (V1):';l2.innerHTML='Final Concentration (C2):';l3.innerHTML='Final Volume (V2):';}}function calculateDilution(){var v1=parseFloat(document.getElementById('val1').value);var v2=parseFloat(document.getElementById('val2').value);var v3=parseFloat(document.getElementById('val3').value);var type=document.getElementById('calc_type').value;var showSteps=document.getElementById('steps').checked;var result=0;var details="";if(isNaN(v1)||isNaN(v2)||isNaN(v3)){alert('Please enter valid numerical values.');return;}if(type=='C2′){result=(v1*v2)/v3;details="C2 = (C1 * V1) / V2 = ("+v1+" * "+v2+") / "+v3;document.getElementById('resultLabel').innerHTML="Final Concentration (C2)";}else if(type=='V1′){result=(v2*v3)/v1;details="V1 = (C2 * V2) / C1 = ("+v2+" * "+v3+") / "+v1;document.getElementById('resultLabel').innerHTML="Stock Volume Needed (V1)";}else if(type=='V2′){result=(v1*v2)/v3;details="V2 = (C1 * V1) / C2 = ("+v1+" * "+v2+") / "+v3;document.getElementById('resultLabel').innerHTML="Final Volume (V2)";}else if(type=='C1′){result=(v2*v3)/v1;details="C1 = (C2 * V2) / V1 = ("+v2+" * "+v3+") / "+v1;document.getElementById('resultLabel').innerHTML="Initial Concentration (C1)";}document.getElementById('resultValue').innerHTML=result.toLocaleString(undefined,{maximumFractionDigits:4});document.getElementById('stepDetails').innerHTML=showSteps?details:"";document.getElementById('answer').style.display='block';}

How to Use the Dilution Calculator

A dilution calculator is an essential tool for chemists, biologists, and laboratory technicians. It helps determine the precise relationship between concentration and volume when a solute is added to a solvent. By using the standard dilution equation, you can quickly find how much stock solution is required or what the final concentration will be after adding more liquid.

To use this calculator, first select which variable you are trying to find from the dropdown menu. Then, enter the three known values. The calculator supports any units (molarity, percent, mg/mL, etc.) as long as you remain consistent across all inputs.

Concentration (C1 and C2)
The amount of solute present in a given volume of solution. Common units include Molarity (M), mg/dL, or mass percentage (%).
Volume (V1 and V2)
The total space the solution occupies. This can be measured in liters (L), milliliters (mL), or microliters (µL).

The Dilution Equation: C1V1 = C2V2

The principle behind the dilution calculator is the conservation of mass. When you add more solvent (like water) to a solution, the total amount of solute stays the same, even though the volume increases and the concentration decreases. The formula used is:

C1 × V1 = C2 × V2

  • C1: The initial concentration of the stock solution.
  • V1: The volume of the stock solution used for the dilution.
  • C2: The desired final concentration of the diluted solution.
  • V2: The final total volume of the solution after dilution.

Step-by-Step Calculation Example

Scenario: You have a stock solution of Sodium Chloride with a concentration of 5M (C1). You need to prepare 500 mL (V2) of a 0.5M solution (C2). How much stock solution (V1) do you need?

Solution:

  1. Identify knowns: C1 = 5M, C2 = 0.5M, V2 = 500 mL.
  2. Rearrange the formula to solve for V1: V1 = (C2 × V2) / C1.
  3. Substitute the values: V1 = (0.5 × 500) / 5.
  4. Calculate: V1 = 250 / 5.
  5. Result: You need 50 mL of the stock solution.

Note: To reach the final volume of 500 mL, you would take the 50 mL of stock and add 450 mL of solvent.

Common Dilution Questions

What is a Dilution Factor?

The dilution factor is the ratio of the final volume to the initial volume (V2/V1). For example, if you dilute 1 mL of stock into a total of 10 mL, the dilution factor is 10, often written as a 1:10 dilution.

Does the calculator work for molarity and percentage?

Yes. This dilution calculator is unit-agnostic. As long as you use the same unit for both concentrations (C1 and C2) and the same unit for both volumes (V1 and V2), the math remains valid.

What is the difference between V2 and the volume of solvent added?

This is a common mistake. V2 is the total final volume. The volume of solvent you must add is actually (V2 – V1). Always ensure you dilute "up to" the final volume mark in a volumetric flask.

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