Nether Portal Calculator
Convert Overworld and Nether coordinates (1:8 ratio) both ways.
Nether coordinates
X 125 · Y 64 · Z -63
Horizontal axes divide by 8 going into the Nether and multiply by 8 coming out — Y stays the same. A portal placed within 16 blocks (Nether) of the ideal position usually links to the same Overworld portal.