If you are squinting or leaning forward to read your screen, your monitor is probably too far away.
If you are squinting, leaning forward, or increasing your OS font size to read your screen clearly, your monitor is probably too far away.
The clearest sign is leaning forward during tasks that require close reading. If you find yourself sitting back and then unconsciously drifting forward as you concentrate, the screen is too far to be comfortable from your default sitting position. Other signs include small UI elements like menus and status bars looking blurry or unclear, eye fatigue despite correct lighting, and needing to increase system font size or display scaling above 100%.
For a 27" 1440p monitor, the maximum comfortable distance is around 36 inches (90 cm). Beyond this, fine text becomes difficult to read without effort. For a 24" 1080p monitor, the limit is closer to 30 inches.
Quick test: Try reading standard body text on a webpage from your current position without adjusting your posture. If it requires effort or slight squinting, you are likely too far away.
The obvious fix. Push the screen toward the back of your desk to bring it within arm's reach of your normal seating position.
Arms let you extend the screen forward toward you, rather than being limited by the fixed depth of the desk surface itself.
If desk depth limits how close you can sit, a 32" screen at the same distance delivers more visual real estate than a 24".
Not a substitute for correct distance, but a short-term fix if hardware changes are not immediately possible.
Calculate the exact right distance for your monitor size and resolution.