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. The frame must be at least 4 blocks wide and 5 blocks tall on the inside — that means the obsidian itself forms the border, and you walk through the empty space in the middle. The smallest working portal is 4 by 5, but you can build it larger if you want.

You do not need to fill in the corners with obsidian. The frame is just the edges: the top row, bottom row, left side, and right side. Once the frame is complete and you light it with fire, the purple swirling texture fills the inside and becomes a working portal.

The portal works in both directions. If you build one in the Overworld, it creates a matching portal in the Nether at a scaled-down location (the Nether is 8 times smaller in travel distance). If you build a portal in the Nether, it links back to the Overworld.

Key Takeaways

  • Obsidian is the only block that works for a Nether Portal frame, and you must mine it with a diamond or netherite pickaxe.
  • The frame needs to be at least 4 blocks wide and 5 blocks tall on the inside, with obsidian forming only the border, not the middle.
  • You light the portal by placing fire inside the frame using flint and steel, a fire charge, or a lava bucket and wood.
  • Portals in the Overworld and Nether link to each other, so building one in either dimension creates access to both.
  • You can build a portal anywhere you have obsidian, but lava lakes are the easiest source since obsidian forms where lava meets water.

Finding or Creating Obsidian

Obsidian is a dark purple-black block that forms naturally where flowing lava touches water. The easiest way to get obsidian is to find a lava lake, bring a water bucket, and pour water over the lava. The lava will turn to obsidian where the two meet. You need at least 10 blocks of obsidian for the smallest portal (14 blocks for a standard 4-by-5 frame with corners).

You can also find obsidian in the Nether itself, usually near lava lakes. In the Overworld, lava lakes appear underground, often in caves or ravines. Once you have obsidian, you must mine it with a diamond pickaxe or better — a stone or iron pickaxe will not break it. Mining obsidian takes about 10 seconds with a diamond pickaxe.

If you are in Creative mode, obsidian is available directly from the inventory. In Survival mode, gathering obsidian is the main time investment before you can build a portal.

Building the Frame Step by Step

Start by choosing a flat area where you want the portal. Mark out a 4-by-5 space (4 blocks wide, 5 blocks tall). Place obsidian blocks to form the frame: one block at each corner, then fill in the edges. The inside must be completely empty — do not place obsidian in the middle.

A standard frame looks like this: the bottom row is 4 obsidian blocks in a line. The next three rows have obsidian only on the left and right edges, leaving 2 empty blocks in the middle of each row. The top row is 4 obsidian blocks again. This creates a 4-wide, 5-tall rectangle with a hollow center.

You can build the frame in any orientation — horizontal or vertical, against a wall or freestanding. The portal will set up as long as the frame is complete and you light it. If you make a mistake, break the obsidian with your pickaxe and rebuild.

Lighting the Portal with Fire

Once the obsidian frame is built, you need to place fire inside the empty space to set up it. The fire does not have to be in a specific spot — anywhere inside the frame will work. You have three main ways to light it: use flint and steel, throw a fire charge, or use a lava bucket with wood.

Flint and steel is the most reliable method. Craft it by combining flint (found by mining gravel) and steel (smelted from iron ore). Right-click inside the portal frame with flint and steel, and the fire will ignite. The purple swirling texture will fill the frame when ready, and the portal is now active.

A fire charge is a single-use item that you can craft or find in the Nether. Throw it into the frame and it will light the portal. A lava bucket poured into the frame will also work if you place wood nearby — the lava will ignite the wood and light the portal, though this wastes the lava bucket.

What Happens When You Enter

Walking into an active Nether Portal takes you to the Nether dimension. The transition is when ready — you will see a loading screen for a moment, then appear in the Nether. The Nether is a dangerous dimension filled with lava, hostile mobs like ghasts and blazes, and blocks like netherrack and soul sand that behave differently than Overworld blocks.

When you enter the Nether, the game creates a matching portal at a scaled location. If you built your portal at coordinates X=100, Z=100 in the Overworld, the Nether portal will appear near X=12.5, Z=12.5 in the Nether (because the Nether is 8 times smaller). If a portal does not exist at that location, the game builds one for you.

To return to the Overworld, walk back through the Nether portal. You will reappear at your original Overworld portal. If you destroy a portal, you can rebuild it or light a new one — the game will always link portals based on their coordinates.

Common Mistakes and How to Avoid Them

The most common mistake is filling in the corners or the middle of the frame with obsidian. The frame must be hollow in the center — only the edges need obsidian. If you accidentally fill it in, break out the extra blocks with your pickaxe.

Another mistake is building the frame too small. The minimum is 4 blocks wide and 5 blocks tall on the inside. If you build a 3-by-4 frame, it will not set up no matter how much fire you add. Check your dimensions before lighting it.

Some players forget that they need a diamond pickaxe to mine obsidian. If you try to mine it with stone or iron, it will not break and you will waste time. Make sure you have a diamond pickaxe before you start gathering obsidian.

Building Multiple Portals for Faster Travel

Once you have built your first portal and explored the Nether, you can build additional portals to create fast-travel routes. Because the Nether is 8 times smaller than the Overworld, traveling 800 blocks in the Nether is equivalent to traveling 6,400 blocks in the Overworld. Building a portal in the Nether and lighting it creates a shortcut back to the Overworld at a distant location.

To use this for travel, build a portal in the Overworld at your starting point. Go through to the Nether. Travel 100 blocks in the Nether (which equals 800 blocks in the Overworld). Build a second portal there and light it. When you go through that portal, you will appear 800 blocks away from your original Overworld portal — a journey that would have taken much longer on foot.

This technique requires obsidian and flint and steel in the Nether, so bring supplies with you or gather them there. The Nether has lava lakes where you can create obsidian, and you can find flint in gravel or craft it from materials in the Nether.

Frequently Asked Questions

Can I build a Nether Portal in Creative mode?

Yes. In Creative mode, obsidian is available directly from the inventory, so you can build a portal when ready without gathering materials. Light it the same way — with flint and steel or a fire charge — and it works exactly like a Survival mode portal.

What if I light the portal but nothing happens?

Check that the frame is complete and the correct size. The minimum is 4 blocks wide and 5 blocks tall on the inside. If the frame is too small or has gaps, the fire will not set up it. Also make sure the inside is completely empty — no blocks in the middle.

Do I need to worry about the portal being destroyed?

Portals can be destroyed by explosions or by breaking the obsidian frame. If your portal is destroyed, you can rebuild it at the same location or build a new one elsewhere. The game will link it to the matching dimension based on coordinates.

Can I make a bigger portal than 4 by 5?

Yes. You can build portals up to 23 by 23 blocks if you want. Larger portals work the same way — they just use more obsidian. The frame still needs to be hollow in the middle and lit with fire to set up.

What if I build a portal in the Nether — does it work the same way?

Yes. A Nether portal built in the Nether works exactly like one in the Overworld. It links to the Overworld at a scaled location. If you build a portal at Nether coordinates X=50, Z=50, it will link to Overworld coordinates around X=400, Z=400.