How to change the hint size of TextInputLayout

In your styles.xml

<style name="TextLabel" parent="TextAppearance.Design.Hint">    <item name="android:textSize">16sp</item></style>

And then in your layout file:

<android.support.design.widget.TextInputLayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:layout_marginLeft="@dimen/activity_horizontal_margin"         android:layout_marginRight="@dimen/activity_horizontal_margin"         android:layout_marginTop="12dp"         app:hintTextAppearance="@style/TextLabel"         android:minHeight="30dp">

Change the TextInputLayout's app:errorTextAppearance in XML.

<android.support.design.widget.TextInputLayout            android:layout_width="wrap_content"            android:layout_height="wrap_content"            app:errorTextAppearance="@style/CustomTextInputLayoutStyle.ErrorTextStyle">

Where CustomTextInputLayoutStyle.ErrorTextStyle is defined in styles.xml as

<style name="CustomTextInputLayoutStyle.ErrorTextStyle" parent="TextAppearance.Design.Error">        <item name="android:textSize">10sp</item></style>

@Santiago Martínez answer only works for hints on non empty Edittext (inside TextInputLayout)

But for empty Edittext, TextInputLayout hint takes property from Edittext textSize.