https://stackoverflow.com/questions/2884625/what-is-difference-between-and-auto-in-silverlight-grid-layout-definitio


The key is that only the `*` rows participate in sharing the remaining space.

In your example:

```xml
<Grid.RowDefinitions>
    <RowDefinition Height="*" />
    <RowDefinition Height="2*" />
    <RowDefinition Height="3*" />
    <RowDefinition Height="Auto" />
</Grid.RowDefinitions>
```

### Step 1: Measure the `Auto` row

Suppose the grid is 600 pixels high, and the `Auto` row's content needs 120 pixels.

The `Auto` row gets exactly **120 px**.

Remaining height:

```
600 - 120 = 480 px
```

### Step 2: Add up the star weights

The remaining rows have weights:

* `*` = `1*`
* `2*`
* `3*`

Total weight:

```
1 + 2 + 3 = 6
```

This is where the **6** comes from.

### Step 3: Divide the remaining space

Each "star" represents one equal share:

```
480 / 6 = 80 px per star
```

Now allocate according to the weights:

| Row  | Weight | Fraction of remaining space | Height |
| ---- | ------ | --------------------------- | ------ |
| `*`  | 1      | **1/6**                     | 80 px  |
| `2*` | 2      | **2/6 = 1/3**               | 160 px |
| `3*` | 3      | **3/6 = 1/2**               | 240 px |

Notice that:

* First row: **1/6** because its weight is **1** out of a total of **6**.
* Second row: **2/6 = 1/3**.
* Third row: **3/6 = 1/2**.

The fractions add up to 1:

[
\frac{1}{6}+\frac{2}{6}+\frac{3}{6}=\frac{6}{6}=1
]

So the first row gets **1/6** of the remaining height simply because its star weight is **1** and the total star weight is **6**. In general, a row with `N*` receives:

[
\frac{N}{\text{sum of all star weights}}
]

of the space left after all `Auto` (and fixed-size) rows have been measured.