Can I solve for different variables?

Yes! This calculator supports reverse solving. You can solve for: Initial concentration, Suspension volume, Final concentration, Final volume.

What units can I use?

This calculator supports multiple unit systems. Select your preferred units from the dropdown menus next to each input field.

Cell Dilution Calculator

Plan serial or single-step dilutions by balancing initial and final cell concentrations with the desired volumes.

Formula shown2 inputs definedUpdated Nov 2025By CalcuTotal TeamFree, no sign-up

Quick Summary

Use this when you need:

Plan inoculum volumes needed to hit a target culture concentration
Determine the stock concentration required to make a working dilution
Check that your pipetting plan preserves the desired final volume

You’ll need:Initial concentration, Suspension volume

You’ll get:Final concentration, Final volume

How this is calculated

Formula:

C1 * V1 = C2 * V2

In plain language:

The calculator keeps the total number of cells (concentration × volume) constant, so specifying any three of the four values lets it solve for the fourth by rearranging the C1V1 = C2V2 relationship.

The formula is always visible so you can verify the math and explain your numbers to anyone who asks.

What these terms mean

Initial concentration

Initial concentration used in the calculation.

Suspension volume

Suspension volume used in the calculation.

Final concentration

Final concentration used in the calculation.

Final volume

Final volume used in the calculation.

When to use this calculator

Plan inoculum volumes needed to hit a target culture concentration
Determine the stock concentration required to make a working dilution
Check that your pipetting plan preserves the desired final volume

Last updated: November 19, 2025

Cell dilution calculator explained

Every culture dilution conserves the total number of cells, meaning the product of concentration (C) and volume (V) stays constant. This calculator rearranges $C_1 V_1 = C_2 V_2$ so you can solve for the missing stock concentration, inoculum volume, final concentration, or final volume without rewriting algebra on a lab bench.

How the conversion works

The basic relationship is:

C_1 V_1 = C_2 V_2

Provide any three of those values and the tool solves for the fourth. For example, to find the aliquot $V_1$ needed to seed a target $C_2$ and $V_2$ , use $V_1 = \\frac{C_2 V_2}{C_1}$ . Results are returned in whichever units you select (mL or L for volumes, any concentration unit such as cells/mL).

Units and conversions

Quantity	Units	Notes
$C_1$	cells/mL, CFU/mL, TU/mL	Represents the stock or inoculum concentration.
$V_1$	mL, L	Volume of stock transferred.
$C_2$	cells/mL	Target concentration after dilution.
$V_2$	mL, L	Final total volume including diluent.

Worked examples

Tenfold dilution
Pipette 1 mL from a $1.0 \\times 10^7$ cells/mL stock into a tube and bring to 10 mL.

C_2 = \\frac{1.0 \\times 10^7 \\times 1}{10} = 1.0 \\times 10^6\\ \\text{cells/mL}

Seed a bioreactor charge
You need 50 mL at $8.0 \\times 10^5$ cells/mL and the inoculum is $5.0 \\times 10^6$ cells/mL.

V_1 = \\frac{8.0 \\times 10^5 \\times 50}{5.0 \\times 10^6} = 8\\ \\text{mL}

Add diluent until the vessel reaches 50 mL, yielding the target density.

Tips and pitfalls

Record all units; mixing mL and L without conversion throws the math off by 1000x.
Adjust for dead volume in pipette tips when planning micro-scale serial dilutions.
When chaining serial dilutions, multiply dilution factors rather than repeating full calculations.
Keep stock concentrations updated with cell counts to avoid using stale numbers.

References and further reading

Frequently Asked Questions

Important Notice

This calculator provides estimates based on the information you provide and standard formulas.

Results should be used for informational purposes only and may not reflect your specific circumstances.

For important decisions, please consult with a qualified professional in the relevant field.

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Calculator info

Version:: v1.0.0
Last reviewed:: Nov 15, 2025
Sensitivity:: medium
References:: 1

Last updated: November 19, 2025

Cell dilution calculator explained

How the conversion works

The basic relationship is:

C_1 V_1 = C_2 V_2

Units and conversions

Quantity	Units	Notes
$C_1$	cells/mL, CFU/mL, TU/mL	Represents the stock or inoculum concentration.
$V_1$	mL, L	Volume of stock transferred.
$C_2$	cells/mL	Target concentration after dilution.
$V_2$	mL, L	Final total volume including diluent.

Worked examples

Tenfold dilution
Pipette 1 mL from a $1.0 \\times 10^7$ cells/mL stock into a tube and bring to 10 mL.

C_2 = \\frac{1.0 \\times 10^7 \\times 1}{10} = 1.0 \\times 10^6\\ \\text{cells/mL}

Seed a bioreactor charge
You need 50 mL at $8.0 \\times 10^5$ cells/mL and the inoculum is $5.0 \\times 10^6$ cells/mL.

V_1 = \\frac{8.0 \\times 10^5 \\times 50}{5.0 \\times 10^6} = 8\\ \\text{mL}

Add diluent until the vessel reaches 50 mL, yielding the target density.

Tips and pitfalls

Record all units; mixing mL and L without conversion throws the math off by 1000x.
Adjust for dead volume in pipette tips when planning micro-scale serial dilutions.
When chaining serial dilutions, multiply dilution factors rather than repeating full calculations.
Keep stock concentrations updated with cell counts to avoid using stale numbers.

Quick Summary

Calculator Tool

How this is calculated

What these terms mean

Initial concentration

Suspension volume

Final concentration

Final volume

When to use this calculator

Cell dilution calculator explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

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Important Notice

Was this calculator helpful?

Found an error?

Calculator info

Cell dilution calculator explained

How the conversion works

Units and conversions

Worked examples

Tips and pitfalls

References and further reading

Frequently Asked Questions

Related Calculators

Cell Doubling Time Calculator

Log Reduction Calculator

Bleach dilution

Dilution factor

Acres Per Hour Calculator

Benadryl Dosage Calculator for Dogs

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