diff --git a/.eslintrc.js b/.eslintrc.js
index ff85e0e..6c7c86d 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -34,13 +34,14 @@ module.exports = {
     "import/prefer-default-export": "off",
     "linebreak-style": "off",
     "max-len": "off",
-    "no-console": "off",
-    "no-new": "off",
-    "no-continue": "off",
-    "no-plusplus": "off",
-    "object-curly-newline": "off",
     "no-alert": "off",
+    "no-console": "off",
+    "no-continue": "off",
+    "no-new": "off",
+    "no-plusplus": "off",
     "no-restricted-globals": "off",
+    "object-curly-newline": "off",
+    "prefer-destructuring": "off",
   },
   env: {
     browser: true,
diff --git a/src/components/toolbar/Toolbar.ts b/src/components/toolbar/Toolbar.ts
index de77049..b07bc79 100644
--- a/src/components/toolbar/Toolbar.ts
+++ b/src/components/toolbar/Toolbar.ts
@@ -3,7 +3,7 @@ import { $, Dom } from 'core/Dom';
 import { ExcelComponentState } from 'core/ExcelComponentState';
 import { ComponentOptionsType } from 'core/ExcelComponent';
 import { createToolbar } from 'components/toolbar/toolbar.template';
-import { initialStyleState } from 'src/constants';
+import { fontSizes, initialStyleState } from 'src/constants';
 
 export class Toolbar extends ExcelComponentState {
   static className = 'excel__toolbar';
@@ -44,11 +44,41 @@ export class Toolbar extends ExcelComponentState {
 
   onClick(event: MouseEvent) {
     const target = $(event.target as HTMLElement);
-    const stringValue = target?.data?.value;
-    if (!stringValue) return;
 
-    const value = JSON.parse(stringValue);
-    const key = Object.keys(value)[0];
+    let stringValue;
+    let value;
+    let key;
+
+    switch (true) {
+      case !!target.closest('[data-change-size]').$el: {
+        const el = target.closest('[data-change-size]');
+
+        if (el.hasClass('disable')) return;
+
+        const currentSize = this.store.getState().currentStyles.fontSize;
+        let idx = fontSizes.findIndex(font => font === currentSize);
+        let nextSize;
+
+        if (el.data.changeSize === 'increase') {
+          nextSize = fontSizes[++idx];
+        } else if (el.data.changeSize === 'decrease') {
+          nextSize = fontSizes[--idx];
+        }
+
+        value = { fontSize: nextSize };
+        key = 'fontSize';
+
+        break;
+      }
+
+      default: {
+        stringValue = target?.data?.value;
+        if (!stringValue) return;
+
+        value = JSON.parse(stringValue);
+        key = Object.keys(value)[0];
+      }
+    }
 
     this.$emitEventToObserver('toolbar:applyStyle', value);
     this.setComponentState({ [key]: value[key] });
diff --git a/src/components/toolbar/toolbar.template.ts b/src/components/toolbar/toolbar.template.ts
index 43763c7..2e1b179 100644
--- a/src/components/toolbar/toolbar.template.ts
+++ b/src/components/toolbar/toolbar.template.ts
@@ -1,5 +1,6 @@
 import { ToolbarStateType } from 'components/toolbar/toolbar-types';
-import { initialStyleState } from 'src/constants';
+import { isLargestFontSize, isSmallestFontSize } from 'core/utils';
+import { fontFamilies, fontSizes, initialStyleState } from 'src/constants';
 
 type ButtonConfigType = {
   icon: string;
@@ -80,21 +81,38 @@ export function createToolbar(state: ToolbarStateType): string {
     ],
   ];
 
-  const buttons = btns.map(btn => (Array.isArray(btn) ? toButtonGroup(btn) : toButton(btn)));
+  const buttons = btns.map(btn => (Array.isArray(btn) ? createButtonsFromConfigGroup(btn) : createButtonFromConfig(btn)));
 
   const selectGroup = createGroup(createFontSizeButton(state.fontSize), createFontFamilyButton(state.fontFamily));
+  const increaseDecreaseFontSize = createSizeUpDownButtons(state.fontSize);
+
+  buttons.push(increaseDecreaseFontSize);
   buttons.push(selectGroup);
-  return buttons.join(' ');
+
+  return buttons.join('');
+}
+
+function createSizeUpDownButtons(currentSize = initialStyleState.fontSize) {
+  const buttons = ['increase', 'decrease'];
+
+  return buttons.map(btn => {
+    const disable = btn === 'increase' ? isLargestFontSize(currentSize) : isSmallestFontSize(currentSize);
+    return `
+      <div class="button${disable ? ' disable' : ''}" data-change-size="${btn}"> 
+        <i class="material-icons">text_${btn}</i>
+      </div>
+    `;
+  }).join('');
 }
 
 function createFontSizeButton(currentSize = initialStyleState.fontSize) {
-  const fontSizeInPixels = +currentSize.slice(0, -2);
-  const options = [];
-
-  for (let i = 8; i <= 24; i += 2) {
-    if (fontSizeInPixels === i) options.push(`<option value="${i}" selected>${i}</option>`);
-    else options.push(`<option value="${i}">${i}</option>`);
-  }
+  const options = fontSizes.map(size => {
+    // remove 'px' part
+    const sizeValue = size.slice(0, -2);
+    return size === currentSize
+      ? `<option value="${sizeValue}" selected>${sizeValue}</option>`
+      : `<option value="${sizeValue}">${sizeValue}</option>`;
+  });
 
   return `
     <div class="button">
@@ -106,12 +124,11 @@ function createFontSizeButton(currentSize = initialStyleState.fontSize) {
 }
 
 function createFontFamilyButton(font = initialStyleState.fontFamily) {
-  const fonts = ['Roboto', 'Cormorant SC', 'Kanit', 'Playfair Display'];
-  const options = fonts.map(fontName => createFontFamilyOption(fontName, fontName === font));
+  const options = fontFamilies.map(fontName => createFontFamilyOption(fontName, fontName === font));
 
   function createFontFamilyOption(name: string, selected: boolean) {
     return selected
-      ? `<option value="${name}" selected style="font-family: ${name}">${name}</option>`
+      ? `<option value="${name}" style="font-family: ${name}" selected >${name}</option>`
       : `<option value="${name}" style="font-family: ${name}">${name}</option>`;
   }
 
@@ -132,22 +149,22 @@ function createGroup(...btns: string[]) {
   `;
 }
 
-function toButtonGroup(buttons: ButtonConfigType[]) {
-  if (buttons.length === 1) return toButton(buttons[0]);
-  const btns = buttons.map(btn => toButton(btn));
+function createButtonsFromConfigGroup(buttons: ButtonConfigType[]) {
+  if (buttons.length === 1) return createButtonFromConfig(buttons[0]);
+  const btns = buttons.map(btn => createButtonFromConfig(btn));
 
   return createGroup(...btns);
 }
 
-function toButton(button: ButtonConfigType) {
+function createButtonFromConfig(btnConfig: ButtonConfigType) {
   const meta = `
     data-type="button"
-    data-value='${JSON.stringify(button.value)}'
+    data-value='${JSON.stringify(btnConfig.value)}'
   `;
 
   return `
-    <div class="button ${button.isActive ? 'active' : ''}"${meta}> 
-      <i class="material-icons" ${meta}>${button.icon}</i>
+    <div class="button ${btnConfig.isActive ? 'active' : ''}"${meta}> 
+      <i class="material-icons" ${meta}>${btnConfig.icon}</i>
     </div>
   `;
 }
diff --git a/src/constants.ts b/src/constants.ts
index fe2b788..2ae2a16 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -4,13 +4,27 @@ import { storageName } from 'pages/ExcelPage';
 import { StateType } from 'redux/types';
 import { storage } from 'core/utils';
 
+export const fontSizes = [
+  '12px',
+  '14px',
+  '16px',
+  '18px',
+  '20px',
+  '22px',
+  '24px',
+  '26px',
+  '28px',
+  '30px',
+];
+export const fontFamilies = ['Roboto', 'Cormorant SC', 'Kanit', 'Playfair Display'];
+
 export const initialStyleState: ToolbarStateType = {
   justifyContent: 'start',
   fontWeight: 'normal',
   textDecoration: 'none',
   fontStyle: 'normal',
-  fontSize: '12px',
-  fontFamily: 'Roboto',
+  fontSize: fontSizes[0],
+  fontFamily: fontFamilies[0],
   alignItems: 'start',
 };
 
diff --git a/src/core/Dom.ts b/src/core/Dom.ts
index 9b2ff2e..5209038 100644
--- a/src/core/Dom.ts
+++ b/src/core/Dom.ts
@@ -105,6 +105,10 @@ export class Dom implements DomClass {
     this.$el?.classList.add(className);
   }
 
+  hasClass(className: string) {
+    return Array.from(this.$el.classList).includes(className);
+  }
+
   removeClass(className: string) {
     this.$el?.classList.remove(className);
   }
diff --git a/src/core/utils.ts b/src/core/utils.ts
index e9aefd6..5cfeebf 100644
--- a/src/core/utils.ts
+++ b/src/core/utils.ts
@@ -1,3 +1,5 @@
+import { fontSizes } from 'src/constants';
+
 export function capitalize(string: string): string {
   if (!string) return '';
 
@@ -49,3 +51,13 @@ export function parse(value: string) {
 
   return value;
 }
+
+export function isLargestFontSize(fontSize?: string): number | boolean {
+  if (!fontSize) return false;
+  return fontSizes.length - 1 === fontSizes.findIndex(el => el === fontSize);
+}
+
+export function isSmallestFontSize(fontSize?: string): number | boolean {
+  if (!fontSize) return false;
+  return fontSizes.findIndex(el => el === fontSize) === 0;
+}
diff --git a/src/styles/components/toolbar.scss b/src/styles/components/toolbar.scss
index 88c459e..aeebbbf 100644
--- a/src/styles/components/toolbar.scss
+++ b/src/styles/components/toolbar.scss
@@ -16,6 +16,10 @@
     @include button(green)
   }
 
+  .button.disable {
+    cursor: not-allowed;
+  }
+
   .button__group {
     border-right: 1px solid #c0c0c0;
     &:last-child {