What you need to build a Nether portal

A Nether portal is a rectangular frame made of obsidian blocks that opens a doorway to the Nether dimension. You need at least 10 obsidian blocks to build the smallest working portal — a 4-block-wide by 5-block-tall frame with the interior hollow. The frame doesn't need a bottom or top, only the four sides.

Obsidian is the hardest material to obtain in vanilla Minecraft survival mode. You find it where water meets lava, usually deep underground or in the Nether itself. When flowing water touches a lava source block, it turns into obsidian. You can also find obsidian in the End dimension or in ruined structures, but the water-and-lava method is the most reliable early-game approach.

To mine obsidian, you must use a diamond pickaxe or better — a stone pickaxe, iron pickaxe, or anything weaker will break the block without dropping it. Wooden and stone pickaxes are useless for obsidian. Once you have the obsidian blocks, you can place them anywhere and build your portal frame in your base or near your spawn point.

Key Takeaways

  • A working Nether portal frame requires at least 10 obsidian blocks arranged in a 4-wide by 5-tall rectangle with a hollow interior.
  • You can obtain obsidian by pouring water onto lava source blocks, then mining the result with a diamond pickaxe or better.
  • Once your frame is built, you light it on fire using flint and steel, a fire charge, or lava to activate the purple portal.
  • The Nether is a hostile dimension with dangerous mobs and terrain — bring armor, weapons, and food before entering.
  • Portals in the Nether and Overworld are linked: traveling through one portal takes you to a corresponding location in the other dimension.

Finding and mining obsidian

The fastest way to get obsidian early in a survival world is to find a lava pool and use water to convert it. Dig down to Y-level 10 or lower (you can see your Y-coordinate in the debug screen by pressing F3 on Java Edition). Look for lava pools — they appear as orange blocks flowing downward. Bring a water bucket with you.

When you find lava, place water on top of it or let water flow onto it from above. The lava will turn into obsidian blocks. You may need to place water multiple times if the lava pool is large. Once the lava has cooled into obsidian, switch to your diamond pickaxe and mine each block. Each obsidian block takes about 9.4 seconds to mine with a diamond pickaxe, so be patient.

If you don't have a diamond pickaxe yet, you'll need to find diamonds first. Diamonds spawn between Y-levels -64 and 16 in Java Edition (the range varies slightly in Bedrock Edition). Mine with an iron pickaxe to collect diamonds, then craft a diamond pickaxe at a crafting table before attempting obsidian.

Building the portal frame

A Nether portal frame is a rectangle made of obsidian. The minimum size is 4 blocks wide and 5 blocks tall, which uses 10 obsidian blocks total. You can build it larger — up to 23 blocks wide and 23 blocks tall — but larger portals use more obsidian and take longer to activate.

Place your obsidian blocks in this pattern: four blocks in a row for the bottom, then three blocks on each side going upward, then four blocks across the top. The interior should be completely empty. You don't need to fill in the bottom or top of the frame — the portal activates as long as the four vertical sides are complete.

You can build the frame lying flat on the ground, standing upright against a wall, or even floating in the air. The orientation doesn't matter. Once the frame is built, move to the next step: lighting it on fire.

Activating the portal with fire

To activate your portal frame, you need to set the interior on fire. You have three ways to do this: use flint and steel, throw a fire charge, or place lava inside the frame.

Flint and steel is the most common method. Craft it by combining one flint (found by mining gravel) and one iron ingot at a crafting table. Right-click inside the empty portal frame with flint and steel in your hand. A spark will ignite the frame, and it will fill with purple swirling particles — this is the active portal.

Fire charges are rarer early-game but work the same way: throw one into the frame and it will activate. Lava works too, but it's harder to control and may spread beyond the frame. Once the portal is lit, it stays active permanently unless you break the obsidian frame itself.

What happens when you enter the portal

Walking into an active Nether portal teleports you to the Nether dimension. The transition takes a few seconds — your screen will turn black briefly. You'll appear in or near a corresponding portal in the Nether. The Nether is a dangerous place with lava lakes, hostile mobs like ghasts and blazes, and terrain that's harder to navigate than the Overworld.

Bring armor, a sword, a pickaxe, and food before entering. The Nether has no passive mobs, so you can't hunt animals there. Bring enough supplies to survive or find your way back to your portal quickly. If you die in the Nether, your items will despawn after five minutes, so retrieving them is urgent.

To return to the Overworld, find or build another Nether portal in the Nether and walk through it. You'll be transported back to your original portal in the Overworld, or to a new portal if the original one was destroyed.

Portal linking and coordinates

Nether portals in Minecraft are linked by coordinates. When you build a portal in the Overworld at coordinates X=100, Z=100, the corresponding Nether portal appears at X=12.5, Z=12.5 (the Nether is 8 times smaller than the Overworld, so coordinates are divided by 8). If a portal doesn't exist at that location in the Nether, one will be created when you enter.

This linking system means you can use portals for fast travel. If you build two portals far apart in the Overworld and travel through one to the Nether, you can walk a short distance in the Nether and build a second portal to exit near your destination in the Overworld. The Nether's smaller size makes it useful for covering long distances quickly.

If you want to control where your Nether portal appears, build it in the Nether at specific coordinates before entering from the Overworld. This prevents the game from creating a new portal at the default linked location.

Troubleshooting common portal problems

If your portal won't light, check that the frame is complete. Every block in the four vertical sides must be obsidian — even one missing block will prevent activation. Also make sure the interior is empty and you're using the correct fire-starting method. Flint and steel is most reliable; if you're using lava, make sure it actually reaches the interior of the frame.

If your portal is lit but won't let you enter, you may be standing too close to the frame. Step back a few blocks and try again. Portals require a small amount of space around them to function. If the portal keeps closing or flickering, another player or mob may be breaking the obsidian blocks — check that the frame is still intact.

If you can't find your Nether portal after returning from the Nether, the portal may have been destroyed or you may have spawned at a different location than expected. Build a new portal in the Nether at the coordinates where you want to exit in the Overworld, or search for the original portal by exploring the area around your spawn point.

Frequently Asked Questions

Can I build a Nether portal without a diamond pickaxe?

No. You need a diamond pickaxe to mine obsidian. Weaker pickaxes will break the block without dropping it. You must find diamonds first, which requires an iron pickaxe. Once you have diamonds, craft a diamond pickaxe and use it to mine obsidian.

What's the smallest Nether portal I can build?

The smallest working portal is 4 blocks wide and 5 blocks tall, using 10 obsidian blocks total. You can't build anything smaller — the game requires at least this size to create a valid portal frame.

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

No. If you entered the Nether through a portal, that same portal still exists in the Nether and will take you back to the Overworld when you walk through it. You only need to build a second Nether portal if you want to exit at a different location in the Overworld.

Can mobs come through my Nether portal?

Yes. Hostile mobs can walk through active portals just like you can. Ghasts and blazes from the Nether can enter the Overworld, and zombies and skeletons from the Overworld can enter the Nether. Build your portal away from your base or use doors and walls to prevent mobs from reaching your home.

What if I break my Nether portal frame?

Breaking any obsidian block in the frame will deactivate the portal immediately. You can rebuild it by placing new obsidian blocks in the same location and lighting it again. If you break the frame completely, you'll need to gather more obsidian and construct a new portal.