diff --git a/packages/lexical-editor-pb-element/src/components/LexicalPresets/HeadingEditorPreset.tsx b/packages/lexical-editor-pb-element/src/components/LexicalPresets/HeadingEditorPreset.tsx
index 82525b9aa88..f35b6770f2e 100644
--- a/packages/lexical-editor-pb-element/src/components/LexicalPresets/HeadingEditorPreset.tsx
+++ b/packages/lexical-editor-pb-element/src/components/LexicalPresets/HeadingEditorPreset.tsx
@@ -15,15 +15,24 @@ import {
     TypographyPlugin,
     UnderlineAction,
     LexicalEditorConfig,
-    LinkPlugin
+    LinkPlugin,
+    useRichTextEditor
 } from "@webiny/lexical-editor";
 
 const { ToolbarElement, Plugin } = LexicalEditorConfig;
 
+const FontSizeActionWithTheme = () => {
+    const { theme } = useRichTextEditor();
+
+    const fontSizes = theme?.styles?.fontSizes?.heading ?? FontSizeAction.FONT_SIZES_FALLBACK;
+
+    return <FontSizeAction fontSizes={fontSizes} />;
+};
+
 export const HeadingEditorPreset = () => {
     return (
         <LexicalEditorConfig>
-            <ToolbarElement name="fontSize" element={<FontSizeAction />} />
+            <ToolbarElement name="fontSize" element={<FontSizeActionWithTheme />} />
             <ToolbarElement name="fontColor" element={<FontColorAction />} />
             <ToolbarElement name="typography" element={<TypographyAction />} />
             <ToolbarElement name="textAlignment" element={<TextAlignmentAction />} />
diff --git a/packages/lexical-editor-pb-element/src/components/LexicalPresets/ParagraphEditorPreset.tsx b/packages/lexical-editor-pb-element/src/components/LexicalPresets/ParagraphEditorPreset.tsx
index 5f2e109963c..1ab46d12175 100644
--- a/packages/lexical-editor-pb-element/src/components/LexicalPresets/ParagraphEditorPreset.tsx
+++ b/packages/lexical-editor-pb-element/src/components/LexicalPresets/ParagraphEditorPreset.tsx
@@ -20,14 +20,24 @@ import {
     UnderlineAction,
     ListPlugin,
     LexicalEditorConfig,
-    LinkPlugin
+    LinkPlugin,
+    useRichTextEditor
 } from "@webiny/lexical-editor";
 
 const { ToolbarElement, Plugin } = LexicalEditorConfig;
+
+const FontSizeActionWithTheme = () => {
+    const { theme } = useRichTextEditor();
+
+    const fontSizes = theme?.styles?.fontSizes?.paragraph ?? FontSizeAction.FONT_SIZES_FALLBACK;
+
+    return <FontSizeAction fontSizes={fontSizes} />;
+};
+
 export const ParagraphEditorPreset = () => {
     return (
         <LexicalEditorConfig>
-            <ToolbarElement name="fontSize" element={<FontSizeAction />} />
+            <ToolbarElement name="fontSize" element={<FontSizeActionWithTheme />} />
             <ToolbarElement name="fontColor" element={<FontColorAction />} />
             <ToolbarElement name="typography" element={<TypographyAction />} />
             <ToolbarElement name="textAlignment" element={<TextAlignmentAction />} />
diff --git a/packages/lexical-editor/src/components/Toolbar/Toolbar.css b/packages/lexical-editor/src/components/Toolbar/Toolbar.css
index 8bc676633ab..93ce67cea77 100644
--- a/packages/lexical-editor/src/components/Toolbar/Toolbar.css
+++ b/packages/lexical-editor/src/components/Toolbar/Toolbar.css
@@ -326,10 +326,6 @@ i.font-color,
   margin: 0 4px;
 }
 
-.toolbar-item.font-size {
-  width: 70px;
-}
-
 .lexical-dropdown-container {
   position: absolute;
   bottom: -5px;
diff --git a/packages/lexical-editor/src/components/ToolbarActions/FontSizeAction.tsx b/packages/lexical-editor/src/components/ToolbarActions/FontSizeAction.tsx
index 4051dbf63eb..8d3eaee1059 100644
--- a/packages/lexical-editor/src/components/ToolbarActions/FontSizeAction.tsx
+++ b/packages/lexical-editor/src/components/ToolbarActions/FontSizeAction.tsx
@@ -6,7 +6,13 @@ import { DropDown, DropDownItem } from "~/ui/DropDown";
 import { useDeriveValueFromSelection } from "~/hooks/useCurrentSelection";
 import { useRichTextEditor } from "~/hooks";
 
-const FONT_SIZE_OPTIONS: string[] = [
+export interface FontSize {
+    id: string;
+    name: string;
+    value: string;
+}
+
+export const FONT_SIZES_FALLBACK: FontSize[] = [
     "8px",
     "9px",
     "10px",
@@ -24,7 +30,18 @@ const FONT_SIZE_OPTIONS: string[] = [
     "60px",
     "72px",
     "96px"
-];
+].map(size => ({
+    id: size,
+    name: size,
+    value: size,
+    default: size === "15px"
+}));
+
+const emptyOption: FontSize = {
+    value: "",
+    name: "Font Size",
+    id: "empty"
+};
 
 function dropDownActiveClass(active: boolean) {
     if (active) {
@@ -34,21 +51,22 @@ function dropDownActiveClass(active: boolean) {
 }
 
 interface FontSizeDropDownProps {
+    fontSizes: FontSize[];
     editor: LexicalEditor;
-    value: string;
+    value: string | undefined;
     disabled?: boolean;
 }
 
 function FontSizeDropDown(props: FontSizeDropDownProps): JSX.Element {
-    const { editor, value, disabled = false } = props;
+    const { editor, value, fontSizes, disabled = false } = props;
 
     const handleClick = useCallback(
-        (option: string) => {
+        (option: FontSize) => {
             editor.update(() => {
                 const selection = $getSelection();
                 if ($isRangeSelection(selection)) {
                     $patchStyleText(selection, {
-                        ["font-size"]: option
+                        ["font-size"]: option.value
                     });
                 }
             });
@@ -56,39 +74,43 @@ function FontSizeDropDown(props: FontSizeDropDownProps): JSX.Element {
         [editor]
     );
 
+    const selectedOption = fontSizes.find(opt => opt.value === value) ?? emptyOption;
+
     return (
         <DropDown
             disabled={disabled}
             buttonClassName="toolbar-item font-size"
-            buttonLabel={value}
+            buttonLabel={selectedOption.name}
             buttonAriaLabel={"Formatting options for font size"}
         >
-            {FONT_SIZE_OPTIONS.map(option => (
+            {fontSizes.map(option => (
                 <DropDownItem
-                    className={`item fontsize-item ${dropDownActiveClass(value === option)}`}
+                    className={`item fontsize-item ${dropDownActiveClass(value === option.id)}`}
                     onClick={() => handleClick(option)}
-                    key={option}
+                    key={option.id}
                 >
-                    <span className="text">{option}</span>
+                    <span className="text">{option.name}</span>
                 </DropDownItem>
             ))}
         </DropDown>
     );
 }
 
-const defaultSize = "15px";
+interface FontSizeActionProps {
+    fontSizes?: FontSize[];
+}
 
-export const FontSizeAction = () => {
+const FontSize = ({ fontSizes = FONT_SIZES_FALLBACK }: FontSizeActionProps) => {
     const { editor } = useRichTextEditor();
     const [isEditable, setIsEditable] = useState(() => editor.isEditable());
     const fontSize = useDeriveValueFromSelection(({ rangeSelection }) => {
         if (!rangeSelection) {
-            return defaultSize;
+            return undefined;
         }
         try {
-            return $getSelectionStyleValueForProperty(rangeSelection, "font-size", "15px");
+            return $getSelectionStyleValueForProperty(rangeSelection, "font-size");
         } catch {
-            return defaultSize;
+            return undefined;
         }
     });
 
@@ -102,7 +124,14 @@ export const FontSizeAction = () => {
 
     return (
         <>
-            <FontSizeDropDown disabled={!isEditable} value={fontSize} editor={editor} />
+            <FontSizeDropDown
+                disabled={!isEditable}
+                value={fontSize}
+                editor={editor}
+                fontSizes={fontSizes}
+            />
         </>
     );
 };
+
+export const FontSizeAction = Object.assign(FontSize, { FONT_SIZES_FALLBACK });
diff --git a/packages/theme/src/types.ts b/packages/theme/src/types.ts
index 0c110ea9396..a5b3539b3a7 100644
--- a/packages/theme/src/types.ts
+++ b/packages/theme/src/types.ts
@@ -27,8 +27,10 @@ export type ThemeBreakpoints = {
 
 /*
  * Typography section
+ * We want to allow custom strings as well, thus the (string & {}).
  */
-export type TypographyType = "headings" | "paragraphs" | "quotes" | "lists" | string;
+// eslint-disable-next-line @typescript-eslint/ban-types
+export type TypographyType = "headings" | "paragraphs" | "quotes" | "lists" | (string & {});
 export type TypographyStyle = {
     id: string;
     name: string;
@@ -39,8 +41,18 @@ export type TypographyStyle = {
 export type Typography = Record<TypographyType, Readonly<TypographyStyle[]>>;
 export type ThemeTypographyStyleItems = TypographyStyle[];
 
+export interface FontSize {
+    id: string;
+    name: string;
+    value: string;
+}
+
 export interface ThemeStyles {
     colors: Record<string, any>;
+    fontSizes?: {
+        heading?: FontSize[];
+        paragraph?: FontSize[];
+    };
     borderRadius?: number;
     typography: Typography;
     elements: Record<string, Record<string, any> | StylesObject>;