# Y Units

The `Y Units` variable controls how a unit is vertically positioned relative to its parent. By default an object is positioned relative to the top of its parent, where each unit represents 1 pixel downward.

## Pixels From Top

The following image shows a child [ColoredRectangle](/gum/gum-tool/gum-elements/coloredrectangle.md) positioned 50 `Pixels From Top` relative to its parent:

![Rectangle with Y Units of Pixels From Top](/files/24q940HYew2xBOBcsQHy)

## Pixels From Center

The following image shows a child ColoredRectangle positioned 50 `Pixels From Center` relative to its parent:

![ColoredRectangle with Y Units of Pixels From Center](/files/KZx2F46047iQ8uBYHFWj)

## Pixels From Bottom

The following image shows a child ColoredRectangle positioned 50 `Pixels From Bottom` relative to its parent:

![ColoredRectangle with Y Units of Pixels From Bottom](/files/x8VL4c2NU1I6aIhmZHYE)

## Percentage Parent Height

The following image shows a child ColoredRectangle positioned 50 `Percentage Parent Height` relative to its parent:

![ColoredRectangle with Y Units of Percentage Parent Height](/files/CtmeTnfmatt5pkvKbyXT)

## Pixels From Baseline

`Pixels From Baseline` positions a child relative to the parent's baseline. If the parent is a Text instance, the baseline is the Y position of the bottom of letters which do not have descenders. For more information on the concept of text baseline, see the baseline Wikipedia page <https://en.wikipedia.org/wiki/Baseline_(typography)>

<figure><img src="/files/ASP3aR07wKmnE333ftLz" alt=""><figcaption><p>Baseline Example</p></figcaption></figure>

The following image shows a child ColoredRectangle positioned 0 pixels relative to a Text instance's baseline.

<figure><img src="/files/LAADytzPEylAjiB2nJO8" alt=""><figcaption><p>ColoredRectangle with <code>Y Units</code> of <code>Pixels From Baseline</code></p></figcaption></figure>

When using `Pixels From Baseline`, the position depends on the font size, baseline definition in the .fnt, and whether the text wraps. For example, changing the `Width` of the Text causes line wrapping which shifts the baseline.

<figure><img src="/files/Ig2V0RfW4EWq49WQeEPX" alt=""><figcaption><p>Baseline Shifts when the parent Width changes</p></figcaption></figure>

A text instance's baseline is defined by its `Font` and `Font Scale` values. These values ultimately create a .fnt file with a `base` value indicating the distance from the top of the text instance to the baseline. For example, an Arial font with Font Size 40 has a `base` value of 36 and a lineHeight of 45.

<figure><img src="/files/OZlJaMKmD7FfIZZxIx4f" alt=""><figcaption><p>Arial with Font Size 40 has a base value of 36</p></figcaption></figure>

This means that 36 pixels fall above the baseline, and 9 pixels (45 - 36) below.

<figure><img src="/files/84uH96Ca79yR8QTHKULW" alt=""><figcaption><p>Base defines the distance from the top of the Text instance to the baseline</p></figcaption></figure>

Note that if the parent is not a Text instance, then the bottom of the parent is used as the baseline. The following image shows a Colored Rectangle using a `Y Units` of `Pixels From Baseline` with a Container parent.

<figure><img src="/files/kWoxRPGEoPdlFbXeAZ4x" alt=""><figcaption><p><code>Pixels from Baseline</code> uses the bottom of the parent if it is not a Text instance</p></figcaption></figure>


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