Adjust font size in three taps on any Kindle device or app
Open the book you're reading. Tap the middle of the screen (on a device) or tap the text (in the Kindle app on your phone or tablet). A menu bar will appear at the top and bottom of the page. Tap the Aa icon — it's usually in the top menu bar and shows a small letter next to a large one. A font size slider will open. Drag the slider to the right to make text larger, or to the left to make it smaller. The change takes effect when ready.
On Kindle e-readers like the Paperwhite or Oasis, the Aa button opens a full settings panel where you can also change the font style, line spacing, and margins at the same time. On the Kindle app for phones and tablets, the same Aa button controls font size, and you may see additional text formatting options depending on which app version you have.
Your font size choice saves automatically for each book. If you read the same book on multiple devices — say, your Kindle device and your phone — the font size you set on one will sync to the others within a few minutes, as long as both devices are connected to the same Amazon account.
Key Takeaways
- Tap the middle of the screen to open the menu, then tap the Aa icon to access font size controls.
- Font size changes save automatically for each book and sync across your devices when you use the same Amazon account.
- Kindle e-readers let you adjust font style, line spacing, and margins from the same menu as font size.
- The Kindle app on phones and tablets uses the same Aa button, though the menu layout may differ slightly by device type.
Where the Aa button appears on different Kindle devices
On Kindle Paperwhite, Oasis, and basic e-readers, the Aa button sits in the top menu bar that appears when you tap the screen. It's one of the first icons you'll see, usually to the left of the battery indicator. Tap it once and a full panel opens showing font size, font style (Serif or Sans Serif), line spacing, margins, and color mode options.
On the Kindle app for iPhone or iPad, tap anywhere in the text and the Aa button appears in the top menu bar. On Android phones and tablets, the same button is in the same place. The layout is consistent across both, though the exact position of other buttons may vary slightly depending on your app version.
On older Kindle devices like the Kindle Voyage or older Paperwhite models, the Aa button is still in the top menu bar. If you don't see it when ready, make sure you've tapped the screen to wake the menu — it disappears after a few seconds of inactivity to keep the page clear.
Font size options and what they look like
Kindle offers a range of font sizes from very small (labeled as size 1) to very large (size 8 or higher, depending on your device). The smallest sizes fit more words per page and let you read longer without turning pages. The largest sizes show fewer words per page but are easier on the eyes if you have vision difficulties or prefer larger text.
There is no "standard" or "default" size — Kindle sets a middle size when you first open a book, but you can move the slider in either direction. Many readers find sizes 3 through 5 comfortable for regular reading. If you're reading for long periods or have trouble with small text, sizes 6 and above are worth trying. The only way to know what works for you is to adjust and read a few pages.
The font size slider shows a preview of how the text will look as you drag it. You can see the change in real time before you release the slider, so you don't have to guess or make multiple adjustments.
Change other text settings at the same time
When you open the Aa menu on a Kindle e-reader, you'll see controls for font style, line spacing, margins, and sometimes color mode. On the Kindle app for phones and tablets, some of these options may be in a separate menu or may not be available, depending on your device and app version.
Font style lets you choose between Serif fonts (with small lines at the ends of letters) and Sans Serif fonts (without those lines). Serif fonts are traditional and often feel more like printed books. Sans Serif fonts are cleaner and sometimes easier to read on screens, especially at smaller sizes.
Line spacing controls how much vertical space appears between lines of text. Wider spacing can make reading easier if you find text crowded, or harder if you prefer more words visible at once. Margins control how much white space appears on the left and right edges of the page. Wider margins can reduce eye strain by narrowing the text column.
Sync font size across devices
If you own both a Kindle device and use the Kindle app on your phone or tablet, your font size choice will sync automatically. This happens through your Amazon account — as long as all your devices are signed into the same account and connected to the internet, Kindle will remember the font size you set for each book and explore it when you open that book on another device.
Syncing usually happens within a few minutes, but can take longer if your devices are offline. If you change the font size on your phone and then open the same book on your Kindle device, you may see the old size briefly before it updates. Close the book and reopen it if the sync doesn't happen automatically.
This sync applies to font size only. Other settings like bookmarks, highlights, and your reading position sync separately through Kindle's "Whispersync" feature, which works the same way.
What to do if the Aa button doesn't appear
If you tap the screen and don't see the menu bar, try tapping again in the exact middle of the page. On some devices, tapping near the edges of the screen opens different menus. If the menu appears but you don't see the Aa button, it may be hidden off-screen — try swiping left or right in the menu bar to reveal more options.
On the Kindle app, make sure you're tapping the text itself, not the margins or the very top or bottom of the screen. If you're in a menu or settings page rather than reading a book, the Aa button won't appear. Go back to your book and try again.
If the Aa button is completely missing and you've tried these steps, restart the app or device. Close the Kindle app entirely and reopen it, or restart your e-reader by holding the power button for 20 seconds. This usually fixes temporary glitches that hide the menu.
Font size doesn't change the book's layout or page count
When you increase font size on a Kindle, the text gets larger but the book doesn't reformat in the way it would in a printed book. Instead, more pages are added to the book — the page count you see in the progress bar will increase because each screen now holds fewer words. This is normal and doesn't mean anything is wrong with your book or device.
The book's content stays the same. Chapters, sections, and all the text remain identical. Only the number of screens you need to read through changes. If you were on page 50 of 300 at size 3, and you increase to size 6, you might now be on page 75 of 450. The actual story or information hasn't changed — you're just seeing fewer words per screen.
Some readers find this confusing at first, but it's actually helpful. It means you can adjust font size without losing your place or worrying that you're missing content.
Frequently Asked Questions
Can I set a default font size so I don't have to adjust it for every book?
No, Kindle doesn't have a global default setting. However, the font size you set for one book will stay at that size for the next book you open — Kindle remembers your last choice. If you always want to read at size 5, just set it to size 5 in your first book, and it will stay there for all future books until you change it again.
Does changing font size work the same way on Kindle for Mac or Windows?
Yes. Open a book in the Kindle app for Mac or Windows, and look for the Aa button in the top menu bar. Tap or click it to open the font size slider. The controls are the same as on phone and tablet apps, though the menu layout may look slightly different depending on your screen size.
What if I want to make the font even larger than the biggest size Kindle offers?
Kindle's largest font size is the maximum the app provides. If that's still too small, you can try increasing the line spacing and margins at the same time, which can make text feel more spacious and easier to read. Some readers also find that switching to a Sans Serif font makes text appear slightly clearer at any size. If you need much larger text, you may want to look into audiobooks or text-to-speech features, which Kindle also supports.
Will changing font size drain my Kindle device's battery faster?
No. Font size doesn't affect battery life on e-readers. The battery drain comes from the e-ink display refreshing the screen, not from how large the text is. On phones and tablets, font size also has no meaningful impact on battery use.
Can I change font size while I'm offline?
Yes. Font size changes work when ready on your current device, whether you're online or offline. The change will sync to your other devices once they connect to the internet, but you don't need to be online to make the adjustment in the first place.