A Nether portal requires obsidian blocks arranged in a specific frame, then lit with flint and steel

A Nether portal is a rectangular frame made of obsidian blocks that opens a doorway to the Nether dimension in Minecraft. The frame must be at least 4 blocks wide and 5 blocks tall on the inside (the obsidian itself forms the border, so the full structure is 6 blocks wide and 7 blocks tall). Once you place the obsidian in the right shape, you light it with flint and steel, a crafted tool that ignites the purple portal block inside the frame.

The Nether is a dangerous dimension filled with lava, hostile mobs, and valuable resources like ancient debris and netherite. Building a portal is your entry point to these materials, but it requires preparation — obsidian is hard to find and flint and steel takes specific ingredients to craft.

Key Takeaways

  • Obsidian forms only where water meets lava, so you need to find or create that situation to collect enough blocks.
  • The minimum portal frame is 4 blocks wide and 5 blocks tall on the inside, requiring 10 obsidian blocks total.
  • Flint and steel is crafted from iron ingots and flint, both found in the Overworld without needing a pickaxe.
  • Once lit, the portal creates a 2-block-wide passage you can walk through to enter the Nether.
  • Portals in the Overworld and Nether are linked — building one in each dimension creates a fast travel route.

Finding or creating obsidian

Obsidian forms when flowing water touches a lava source block. You can find it naturally in the Overworld near lava lakes, but the easiest method is to create it yourself. Dig down to Y-level 10 or lower (check your coordinates with F3 on Java or the debug screen on Bedrock), find a lava pool, and pour water on top of it using a bucket. The lava will turn to obsidian where the water touches it.

You need a diamond or netherite pickaxe to mine obsidian — a stone pickaxe will not break it. If you do not have a diamond pickaxe yet, you can find obsidian in the End dimension (the stronghold contains it) or in the Nether itself, but that creates a circular problem if you are trying to reach the Nether for the first time. The water-and-lava method is the most reliable path for a first portal.

Collect at least 10 obsidian blocks. A standard 4×5 portal uses exactly 10 blocks, but having extras lets you repair the portal if it breaks or build a second one later.

Gathering flint and steel

Flint and steel is crafted from one iron ingot and one flint. Iron ingots come from smelting iron ore in a furnace — iron ore is common in caves and mines at any depth. Flint drops from gravel blocks when you break them with a shovel; it appears randomly, so you may need to break 10 to 20 gravel blocks to get one flint.

Once you have one iron ingot and one flint, open your crafting table and place the iron ingot in the top-left corner and the flint directly below it. This produces one flint and steel. You only need one to light the portal, but crafting a second one is useful in case you lose the first or need to relight the portal if it breaks.

Building the portal frame

Choose a flat location where you have space to build a 6-block-wide by 7-block-tall structure (the obsidian border plus the empty space inside). Place obsidian blocks in a rectangle: the bottom row is 4 blocks wide, the two side columns are 5 blocks tall, and the top row is 4 blocks wide. This creates a hollow rectangle with a 4×5 empty space in the middle.

The corners of the frame must be obsidian, but the corners are optional — you can build a 4×5 frame with just the edges, leaving the four corner positions empty. This saves obsidian if you are short on blocks. The portal will still work as long as the four sides are complete.

Double-check that the inside space is exactly 4 blocks wide and 5 blocks tall before lighting it. If the frame is the wrong size, the portal will not set up.

Lighting the portal and entering the Nether

Stand in front of the empty frame and hold the flint and steel in your hand. Right-click (or use your secondary action button) on any of the obsidian blocks that form the frame. A purple, swirling block will appear inside the frame — this is the portal. Walk into the purple area and you will be transported to the Nether.

The first time you enter the Nether, you will spawn in a random location. The Nether is much more dangerous than the Overworld: zombified piglins, ghasts, and blazes attack on sight, lava is everywhere, and the terrain is chaotic. Bring armor, a sword, and a water bucket before entering. The water bucket lets you extinguish lava and create safe landing spots if you fall.

When you want to return to the Overworld, walk back into the purple portal. You will exit near the location where you built the portal in the Overworld.

Linking portals between dimensions

Portals in the Overworld and Nether are mathematically linked. If you build a portal at coordinates X=100, Z=100 in the Overworld, the Nether will look for a portal at X=12.5, Z=12.5 (the Nether is 8 times smaller). If no portal exists at that location, the game creates a new one for you when you enter.

You can use this to create fast travel routes. Build a portal in the Overworld at a location you want to reach quickly, enter the Nether, and then build a second portal in the Nether near where you spawned. When you return to the Overworld through that second portal, you will exit at a location far from your original portal — effectively teleporting across the Overworld in seconds.

This only works if you build the Nether portal yourself. If you use a naturally generated Nether fortress portal, it links to a specific Overworld location that may not be useful to you.

Repairing a broken portal

Portals can be destroyed by explosions, lava, or other players in multiplayer. If your portal breaks, you do not need to rebuild the entire frame — just replace the missing obsidian blocks and light it again with flint and steel. The portal will reactivate when ready.

If you are trapped in the Nether without flint and steel, you cannot light a portal to escape. Always carry extra flint and steel or the materials to craft it when exploring the Nether. Some players keep a crafting table and furnace in the Nether for this reason.

Frequently Asked Questions

Can I build a portal smaller than 4 blocks wide?

No. The minimum inside dimensions are 4 blocks wide and 5 blocks tall. A 3×4 portal will not set up. You can build larger portals — up to 23×23 — but the smallest working size is 4×5.

What if I do not have a diamond pickaxe to mine obsidian?

Use the water-and-lava method to create obsidian in place, then mine it with a stone pickaxe and collect the drops. Obsidian only drops when mined with a diamond or netherite pickaxe, but you can still break it with stone — you just will not get the block back.

Do I need to build a portal in the Nether to return to the Overworld?

No. Any portal in the Nether will send you back to the Overworld, even if you did not build it. However, you will exit at the linked Overworld location, which may not be where you want to be. Building your own portal in the Nether gives you control over where you exit.

Can mobs come through my portal?

Yes. Zombified piglins, ghasts, and other Nether mobs can walk through your portal into the Overworld. Build your portal in a safe location and consider placing a door or fence gate nearby to prevent mobs from escaping into your base.

What happens if I destroy the obsidian frame while the portal is active?

The portal closes when ready. You will be ejected from the portal if you are standing in it. You can rebuild the frame and light it again to reopen the portal.