How to build a Nether portal in Minecraft (and link two portals)

A Nether portal is an upright Obsidian frame, at least 4 blocks wide and 5 tall, lit with fire. Build it in the Overworld, light the inside and stand in it for 4 seconds. To make two portals lead to each other, build the second one at your Overworld coordinates divided by 8. Numbers below are from the Java Edition 26.3 game code.

The smallest portal takes 10 Obsidian, because the four corners are optional. There are three ways to get it:

• Mine it with a Diamond Pickaxe or a Netherite Pickaxe. Any other pickaxe breaks the block without dropping it.
• Cast it in place without a diamond pickaxe: put a lava source where a frame block goes, then let water flow onto it. A lava source touched by flowing water turns into Obsidian on the spot. Carry a Water Bucket and several Lava Buckets.
• Loot a ruined portal. Their chests can hold 1 or 2 Obsidian, Flint and Steel and Fire Charges. The Crying Obsidian around them does not work in a frame.

With cheats on, /locate structure #minecraft:ruined_portal gives the nearest ruined portal. More on the structure on the ruined portal page.

Stand the frame upright on any solid ground: 2 Obsidian at the bottom, a column of 3 on each side, 2 on top. The opening must be at least 2 blocks wide and 3 tall, and at most 21 × 21. The inside must be empty: a flower, a torch or a snow layer in the opening stops the portal from forming.

Only Obsidian counts as frame. A size in between works too: the count without corners is 2 × (width + height) of the opening.

Use Flint and Steel (1 Iron Ingot and 1 Flint, shapeless) or a Fire Charge on a bottom Obsidian block, from inside the frame. Any fire that appears in the opening lights it. The purple portal fills the whole opening. Fire only opens a portal in the Overworld and in the Nether: a frame built in the End stays empty.

Stand in the portal: in Survival it takes 4 seconds (80 ticks), in Creative it is instant. If no portal exists near your arrival point, the game builds one for you. Before you leave it, write down its position:

• Java Edition: press F3 and read the XYZ line.
• Bedrock Edition: turn on Show Coordinates in the world settings.

Bring a few blocks: the generated portal can open next to a drop or a lava lake.

The Nether is 8 times smaller than the Overworld. Divide X and Z by 8 to go from the Overworld to the Nether, and multiply by 8 for the way back. Y is not scaled. An Overworld portal at X 800, Z -1200 links to a Nether portal at X 100, Z -150. Type your own coordinates in the converter:

Go to the converted X and Z, dig in if needed, and build and light a new portal there, at a Y close to the Y of the other portal. When you step through, the game turns your position into a target point, then picks the closest existing portal around it. Distance is measured in all three axes, so Y matters too.

That gap explains most broken links: two Overworld portals up to 128 blocks apart can both end up in the same Nether portal. Built at the exact coordinates, each portal is the closest to its own target, so the link works both ways. Bedrock Edition uses the same 8:1 scale; the search distances in the table are those of Java Edition.

Go through from the Overworld, check with F3 that you came out of your new portal, then go back and check the Overworld side. If you land in the wrong portal, break one Obsidian block of the wrong one or move your new portal closer to the exact converted point. An explosion inside the portal switches it off while the Obsidian survives, so a Ghast fireball can leave you stranded: keep a Flint and Steel to light it again. The Nether fortress is usually the first trip worth a linked portal: see the blaze farm guide.