> ## Documentation Index
> Fetch the complete documentation index at: https://docs-cbf.growthtak.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Body weight & sampling

> Capture accurate average body weight by sampling birds, with manual or connected-scale input.

Body weight is one of the most important numbers in a batch — it drives weight-vs-standard charts, daily gain, and FCR. GrowTak captures it through the **weight input** on the [day entry](/daily-entry/recording-a-day-entry) form, with built-in **sampling**.

## Why sample?

You can't weigh every bird, so you weigh a **sample** and use the average. GrowTak lets you record several samples and works out the average for you — far more reliable than guessing a single figure.

## Manual sampling

In the body-weight field:

<Steps>
  <Step title="Add a sample">
    Enter a group's **count** and **total weight** (or per-bird weight, depending on your method). Add as many samples as you took.
  </Step>

  <Step title="Apply">
    GrowTak averages the samples and fills in the **average body weight** for the day.
  </Step>

  <Step title="Choose the unit">
    Usually **Kilogram** or **Gram**. Weights are stored to the decimal precision set by **Bird Weight Decimal Places** in [Company Settings](/setup/company-settings).
  </Step>
</Steps>

When samples are recorded, the entry is tagged **Auto** weight source; a single typed figure is tagged **Manual**. You can see this **Weight Source** badge in the day entries list.

## Connected weighing scales

The weight input can connect directly to a **Bluetooth** or **Serial (USB)** weighing scale, so readings flow in without typing. (This is the same sampling tool used when [lifting birds](/lifting-gc/lifting-intents).)

* Tap **Bluetooth** or **Serial (USB)** to connect.
* Each reading from the scale is added as a sample.
* The **Activity Log** shows what's been captured; press **Apply** to set the average.

<Tip>
  A connected scale removes transcription errors and speeds up weighing day — especially useful at lifting, when you weigh many birds quickly.
</Tip>

## Weighing days

You don't weigh every day. The **Weight Rule Every** setting (default **7** days) defines the weighing rhythm. On a weighing day:

* **Body weight becomes required** for a placed batch.
* Recording **feeder leftover** is recommended so FCR reconciles.
* The **Weight Reminder** alert and report flag batches that are due.

<Note>
  Counting starts from placement (day 0). With the default rule of 7, weights are expected on days 0, 7, 14, 21, and so on.
</Note>