A Nether portal is your doorway to the Nether, the fiery dimension where you find blaze rods, ancient debris for netherite, and shortcut travel across the Overworld. Building one is simple once you understand the obsidian frame, the legal sizes, and how the game decides where you come out on the other side. This guide walks through every step and the tricks that experienced players use, with every mechanic checked against the official Minecraft Wiki.
What you need to build a Nether portal
You need two things: obsidian for the frame and a way to light it. Obsidian forms when flowing water touches a lava source block. To collect the obsidian you mine, you must use a diamond pickaxe or better. Anything below diamond tier still breaks the block, but it drops nothing and just wastes your time. With a diamond pickaxe each block takes about 9.4 seconds to mine (a netherite pickaxe shaves that to roughly 8.35 seconds).
To ignite the portal you can use flint and steel or a fire charge. The wiki also lists other ignition sources that work: the impact of a (ghast) fireball or small fireball, a lightning strike, or fire spreading naturally from a flammable block placed next to the obsidian. Flint and steel is by far the most reliable method.
Step-by-step: building the frame
- Gather obsidian. The smallest portal needs as few as 10 blocks (see sizes below).
- Build a vertical, rectangular frame. A Nether portal cannot be laid flat like an End portal, it must stand upright.
- Leave the inside open. The minimum interior opening is 2 blocks wide by 3 blocks tall.
- Light the inside face of the frame with flint and steel. The empty interior fills with purple portal blocks.
- Step in. In Survival there is a short delay (80 game ticks, about 4 seconds) before you are teleported; in Creative the delay is just 1 tick.
The corner trick: the four corners of the frame are not required. A full rectangle uses 14 obsidian, but if you skip the corners the same portal still works with only 10 blocks. This is the single biggest obsidian-saver early game when you may only have a handful of blocks. Note that portals the game generates automatically always include the corners.
Nether portal sizes
Portals can be much larger than the classic doorway. The frame can range from a 4×5 minimum (outer dimensions) up to a 23×23 maximum. Bigger portals are purely cosmetic for travel, but they matter for some mob designs and look impressive on a server build.
| Portal property | Value |
|---|---|
| Minimum frame size (outer) | 4 × 5 |
| Minimum interior opening | 2 × 3 |
| Maximum frame size (outer) | 23 × 23 |
| Obsidian with corners (minimum) | 14 blocks |
| Obsidian without corners (minimum) | 10 blocks |
| Orientation | Vertical only |
| Survival teleport delay | 80 ticks (~4 sec) |
The 1:8 ratio and portal linking
Horizontal coordinates in the Nether are proportional to the Overworld at a 1:8 ratio. Travelling 1 block in the Nether moves you 8 blocks in the Overworld, which is why the Nether is so useful for fast travel. Your Y (height) coordinate does not change between dimensions.
When you enter a portal, the game looks for an existing portal near the converted coordinate. The search area is large in the Overworld (a 256×256 region, a 128-block radius) and small in the Nether (a 32×32 region, a 16-block radius). If it finds a portal in range, it links to it; if not, it generates a new one.
Linking trick: to get two portals to connect exactly where you want, divide your Overworld X and Z by 8 (rounding down) to get the Nether coordinates, then build the matching portal yourself at that spot in the Nether rather than letting the game place one for you. Manually building both ends prevents the misaligned portals that frustrate so many players. Keeping separate portal pairs at least 128 Overworld blocks (16 Nether blocks) apart stops them from hijacking each other’s links.
Java vs Bedrock: who can trigger a new portal
This is the detail people most often get wrong, and it is an edition difference, not a gamerule. In Java Edition, almost any entity (every mob except the wither and the ender dragon) that travels through a portal can trigger the automatic creation of a new portal on the other side if none exists in range. In Bedrock Edition, only a player can trigger that automatic creation, mobs cannot. This matters for mob-transport and farm designs that rely on pushing mobs through portals.
The zombified piglin problem
In Java Edition, zombified piglins have a chance to spawn on the bottom frame of a lit portal in the Overworld when the portal block is ticked. They spawn twice as often on Normal difficulty as on Easy, and three times as often on Hard as on Easy, so a base portal on Hard can leak hostile mobs over time. Lighting the build carefully and walling off the bottom row, or playing on Peaceful, avoids the issue around your home base. This same spawning behaviour is the basis of dedicated gold farms in the Nether.
Where to go from here
Once your portal is live, the Nether opens up the late game. Use our Nether survival guide to stay alive over there, hunt ancient debris with the netherite guide, and once you have blaze rods and ender pearls, work toward beating the ender dragon.
FAQ
What is the minimum obsidian needed for a Nether portal?
Ten obsidian blocks. The four corner blocks are not required, so you can skip them and still light a working 4×5 portal. A complete rectangular frame including the corners uses 14 blocks.
How big can a Nether portal be?
The frame can be anywhere from a 4×5 minimum to a 23×23 maximum (outer dimensions). It must always be built vertically, you cannot lay a Nether portal flat the way an End portal sits on the ground.
Why did my portal come out somewhere unexpected in the Nether?
Because the game searched for a nearby portal at your converted coordinates and either linked to the wrong one or generated a fresh portal at the closest valid spot. Divide your Overworld X and Z by 8 and build the matching portal manually at that exact Nether location for predictable linking.
Building portals together is a lot more fun with friends. Spin up a Minecraft server to play with friends and explore the Nether as a group, and check the Minecraft server setup docs when you are ready to configure your world.
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