A Nether Portal Needs Obsidian Blocks Arranged in a Specific Frame

A Nether portal is a rectangular frame made of obsidian blocks that opens a doorway to the Nether dimension in Minecraft. The frame itself is 4 blocks wide and 5 blocks tall on the inside — meaning you need 14 obsidian blocks total, arranged so the corners and edges form a hollow rectangle. You do not fill in the middle; the empty space is what becomes the portal.

The portal activates when you light the inside of the frame with flint and steel or a fire charge. Once lit, the inside fills with a purple swirling texture, and you can walk through it. The portal works both ways: you can enter from the Overworld to reach the Nether, and you can build or find a portal in the Nether to return home.

Key Takeaways

  • A Nether portal frame is 4 blocks wide and 5 blocks tall on the inside, made entirely of obsidian blocks.
  • You can obtain obsidian by mining it with a diamond or netherite pickaxe, or by pouring water over lava in a specific way.
  • Light the inside of the frame with flint and steel (crafted from iron ingots and flint) or a fire charge to set up the portal.
  • The portal will transport you to the Nether when you walk through, and you can return by building another portal there or finding an existing one.

How to Gather Obsidian Without Mining It

Mining obsidian takes time because you need a diamond or netherite pickaxe — anything weaker will break the block without dropping it. If you do not have a diamond pickaxe yet, you can create obsidian by pouring water over lava. Find a lava source block (usually in caves or near the bottom of the world), then pour a water bucket over it. Where the water meets the lava, obsidian forms when ready.

This method works best in a controlled space. Dig a small trench, place a lava source block in it, then pour water from above. The obsidian will form in a line where they meet. You can then mine it with any pickaxe and collect it. Repeat this process until you have 14 blocks. This approach is faster than searching for diamonds if you are early in your game.

Arranging the Blocks in the Correct Shape

The frame must be a hollow rectangle: 4 blocks wide and 5 blocks tall on the inside. This means the outer dimensions are 6 blocks wide and 7 blocks tall. You can build it on the ground, on a platform, or even floating in the air — the location does not matter, only the shape.

Start by placing obsidian blocks in a line 4 blocks long. Then build up from each end, making two vertical columns that are 5 blocks tall. Finally, connect the tops with a horizontal line of 4 blocks. The result is a rectangular frame with an empty space in the middle. If you make it 3 blocks wide or 4 blocks tall, it will not work — the dimensions must be exact.

Crafting Flint and Steel to Light the Portal

Flint and steel is the most common way to set up a portal. You craft it by combining one iron ingot and one flint in a crafting table. Iron ingots come from smelting raw iron (found by mining iron ore) in a furnace. Flint comes from breaking gravel blocks — gravel drops flint randomly, so break several gravel blocks until you collect at least one.

Once you have flint and steel in your inventory, hold it in your hand and right-click (or use your secondary action button) on any block inside the portal frame. A small flame will appear, and the entire frame will fill with purple swirling energy. If nothing happens, check that your frame is the correct size and that all blocks are obsidian.

What Happens When You Step Through

Walking into an active portal transports you to the Nether, a dangerous dimension filled with lava, hostile mobs, and valuable resources. You will arrive at a corresponding portal location in the Nether — the game calculates this based on your coordinates in the Overworld. If no portal exists at that location in the Nether, the game creates one for you.

The Nether is much more dangerous than the Overworld. Ghasts shoot fireballs, Blazes attack with fire, and Hoglins charge at you. Bring armor, weapons, and food before entering. To return home, you can either walk back through the same portal (if it still exists) or build a new one in the Nether using obsidian you find there.

Troubleshooting a Portal That Will Not Light

If flint and steel does not work, the most common cause is that the frame is the wrong size or has a gap. Count the inside dimensions carefully: 4 blocks wide and 5 blocks tall. Check that every block is obsidian and that none are missing. Even a single missing block will prevent set up.

Another possibility is that you are clicking the wrong spot. You must click inside the frame, not on the obsidian blocks themselves. If you have checked the size and all blocks are present, try clicking in the center of the frame. If it still does not work, break the frame and rebuild it, paying close attention to the exact dimensions.

Frequently Asked Questions

Can I build a Nether portal in the Nether to go back to the Overworld?

Yes. A portal in the Nether works exactly the same way as one in the Overworld. Build a frame of obsidian, light it with flint and steel, and it will transport you back to the Overworld. The game links portals based on coordinates, so a portal in the Nether near your coordinates will usually connect to your Overworld portal.

What if I lose my portal in the Nether?

You can build a new one using obsidian found in the Nether. Obsidian appears naturally in the Nether, especially near lava lakes. Once you have 14 blocks, build a frame and light it. It will create a new connection back to the Overworld, though not necessarily to your original portal location.

Do I need the exact frame size, or can I make it bigger?

The frame must be exactly 4 blocks wide and 5 blocks tall on the inside. You cannot make it larger or smaller. However, you can build multiple portals if you want different entry points in different locations.

Can mobs come through my portal?

Yes. Hostile mobs from the Nether can walk through a portal just as you can. Keep your portal in a safe location, away from your main base, or build a protective structure around it so mobs cannot reach you when you return.