Nether Coordinate Converter
Enter a portal location and the destination is shown immediately. X and Z scale by 8; Y stays the same.
Portal pairing guide
Overworld → Nether
Divide X and Z by 8, then build the Nether portal near that destination.
Nether → Overworld
Multiply X and Z by 8. Y is copied instead of scaled.
Minecraft may choose another nearby portal if multiple portals are within its search area. Treat the result as the target location, not a guarantee of the exact portal link.