# Determine concentration of inoculum

We want to inoculate using a well-defined seeding concentration of cells. For this you need to know the cell concentration of the liquid culture used to seed the growth medium. A 1:10 000 dilution is usually suitable for the BactoBox® measurement. See [Hit the right concentration](https://help.sbtinstruments.com/protocols/prepare-your-sample/hit-the-right-concentration) if the result is not within the working range.

## Step by step

{% stepper %}
{% step %}
**Retrieve a sample of the inoculum**

Swirl the inoculum well to suspend cells and use a sterile serological pipette to collect 1 mL sample. Transfer to a sterile 5 mL centrifuge tube
{% endstep %}

{% step %}
**Disaggregate cell clumps**

Vortex the sample 1 min at max speed to disaggregate cell clumps.
{% endstep %}

{% step %}
**Dilute 1:100**

Transfer 101 µL of T0 culture to 10 mL of diluent. Vortex 10 sec. at max speed.
{% endstep %}

{% step %}
**Dilute 1:10 000**

Transfer 101 µL of the 1:100 dilution to 10 mL of diluent. Vortex 10 sec. at max speed.
{% endstep %}

{% step %}
**Measure**

Transfer tubing kit to the diluted sample. Press <kbd><mark style="background-color:purple;">Measure<mark style="background-color:purple;"></kbd> and wait for the result to appear on the BactoBox® screen.
{% endstep %}

{% step %}
**Calculate concentration**

Multiply the cells/mL result with the dilution factor, in this case 10 000, to get the cell concentration of the inoculum
{% endstep %}
{% endstepper %}

## Summary

Once you know the cell concentration of the inoculum, proceed to [Inoculate culture](/mpd/workflows/get-starter-cultures/from-liquid-culture/inoculate-culture.md).


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