> For the complete documentation index, see [llms.txt](https://help.sbtinstruments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sbtinstruments.com/more/software/plot-a-growth-curve.md).

# Plot a growth curve

Follow cell concentration and cell size over time, with one line per culture.

A growth curve shows how the cell concentration in your culture changes over time. BactoBox® counts the cells directly, so the curve shows how fast your cells divide. Access draws the curve for you when each measurement has a label and a sampling time.

## Set up the measurement group

{% stepper %}
{% step %}

#### Create a *Growth curve* group

Create a measurement group of the type *Growth curve*. See [Create and open measurement groups](/more/software/create-and-open-measurement-groups.md).
{% endstep %}

{% step %}

#### Give each culture its own label

Access draws one line per label. Use the same label for every sample from the same culture, for example *Bioreactor#1*.
{% endstep %}

{% step %}

#### Set *Sampled at* for each sample

Set *Sampled at* to the moment you take the sample from your culture. Then measure. See [Label your samples](/more/software/label-your-samples.md).
{% endstep %}
{% endstepper %}

## Read the plots

For each label, Access plots two values against time:

* the cell concentration of your undiluted sample, in cells/mL
* the cell size, [CIZE](/more/software/cell-size-cize.md)

<div data-with-frame="true"><figure><img src="https://4216107837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeYTtd7c0A325muFr5lMW%2Fuploads%2Fpmo4fPQziUWA8k8b7Orb%2F21-growth-curve-plot.png?alt=media&#x26;token=1384cb42-8451-4fb0-b878-bcd3d36dfb06" alt="A growth curve measurement group in Access."><figcaption><p>A growth curve in Access. The table is on the left and the plot on the right.</p></figcaption></figure></div>

The time axis is *calcHPI*, in hours. Access counts the hours from the first sample with each label. So time zero is your first sample, not the moment you inoculated. To count from inoculation, enter the hours post-inoculation in the *HPI* column for every sample with that label. Access then uses your values. See [How Access calculates calcHPI](/more/software/what-the-columns-mean.md#how-access-calculates-calchpi).

<div data-with-frame="true"><figure><img src="https://4216107837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FeYTtd7c0A325muFr5lMW%2Fuploads%2FNtvagCm6eYaYrXlf5PiX%2F08-calchpi-tooltip.png?alt=media&#x26;token=43820859-228a-4840-b726-b0facf00390d" alt="The tooltip on the calcHPI column in Access." width="600"><figcaption><p>Hover over the <em>calcHPI</em> column header to see how Access calculates it.</p></figcaption></figure></div>

## Share the growth curve

Click *Export report* to print the plots and values of the group, or to save them as a PDF. Click *Export CSV* to work on the values in a spreadsheet. See [Export your data](/more/software/export-your-data.md).


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