How to use
In Minecraft: Java Edition, you can access your current coordinates by opening the debug screen. Press the F3 key on your keyboard to overlay this while in game. Your coordinates are displayed on the left side of the window, labeled as X, Y, and Z. X and Z are your horizontal coordinates, and Y is your vertical coordinate or height.
Just want to see the coordinates without the extra fluff? Use the Coordinates Mod within Lunar Client for a stylish way to view your coordinates at all times!
F3 Debug Screen
How it works
In Minecraft: Java Edition, the Nether operates on a different scale compared to the Overworld. Every block traveled in the Nether equates to eight blocks in the Overworld. This is why Nether portals are a convienent method to travel at speed across large distances.
When you build a Nether portal in the Overworld, its coordinates are divided by eight to determine the portal's location in the Nether. For example, if you build a portal at (80, 64, 80) in the Overworld, it will appear at (10, 64, 10) in the Nether.
Conversely, when you build a portal in the Nether, its coordinates are multiplied by eight to determine the portal's location in the Overworld. So, a portal at (10, 64, 10) in the Nether will appear at (80, 64, 80) in the Overworld.
Please note that the Y-coordinate (height) is not scaled. Also, if a portal in one dimension corresponds to a location in the other dimension where a portal cannot be safely placed (for example, in the middle of a lake or inside a mountain), the game will search for a suitable nearby location. This in turn can affect the exact placement of the portal.