> 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/use-the-calculators.md).
# Use the calculators
Work out how much culture to transfer, and which dilutions to plate.
Access has two calculators under *Tools* in the side bar. The *Subcultivation calculator* tells you how much culture to transfer to fresh medium. The *Plating calculator* tells you which dilutions to plate.
## Start from a measurement
Open a measurement group, right-click the row number of a measurement, and pick a calculator. Access fills in the cell concentration of your undiluted sample (*Cells/mL × Dil.*) for you.
You can also open a calculator from *Tools* in the side bar and type in the concentration yourself.
## Subcultivation calculator
Use the *Subcultivation calculator* to inoculate fresh medium at a set cell concentration. Enter the volume of fresh medium and the target concentration. Access tells you the volume of culture to add.
For example, to start 50 mL of fresh medium at 1 × 106 cells/mL, enter 50 mL under *Fresh medium volume* and 1 × 106 cells/mL under *Target inoculation concentration*.
The Subcultivation calculator, opened from a measurement.
## Plating calculator
Use the *Plating calculator* to plan plate counts without plating a full dilution series. Pick the volume you plate:
* *1 mL* for Petrifilm, compact dry or pour plates
* *0.1 mL* for spread plates
* *Custom* for any other volume
Access tells you how many 1:10 dilutions to make, and which three to plate. Each 1:10 dilution transfers 1 mL of sample into 9 mL of dilution liquid. Access aims the middle plate at the countable range of 25–250 CFU. The two extra plates cover you if your plate count differs from the BactoBox® count.
The Plating calculator for a sample at 6 × 107 cells/mL, plated at 1 mL.
{% hint style="info" %}
### Plate counts measure culturability
A plate count only counts the cells that form a colony. BactoBox® counts every whole cell. In exponential and early stationary phase, the two follow each other closely. Later, cells that no longer form colonies still count on BactoBox®, so your plate count can fall below the BactoBox® count.
{% endhint %}
---
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