The size of Facebook is set not by the website itself, but by the browser or the computer. If you've accidentally zoomed out, and the website appears very small, you can easily zoom back in until it displays in its usual size. There are a few ways of doing this, but the easiest method involves using the "Ctrl" button on your keyboard.
Visit Facebook and sign into your account.
Push and hold the "Ctrl" key on your computer. Tap the "+" button on your keyboard to zoom in, until the desired zoom level is reached. If you zoom in too far, tap "-" while holding "Ctrl" to zoom out.
Click the browser "View" button and select "Zoom" and "Zoom In" to zoom back in, until Facebook is at the desired size.
Tips & Warnings
- On MacBooks and some Windows laptops, you can also use the touchpad to zoom in or out. To zoom in, place two fingers on the touchpad and pinch them together. To zoom out, pull them apart.