Building The Frame
The first thing people get wrong is the block count. A standard 4-wide by 5-tall portal requires exactly 23 blocks of obsidian. The corners are filled in. The interior is hollow. Inside that rectangle, the space needs to be at least 2 blocks wide and 3 blocks tall for the portal to actually form. You can make it bigger—up to 23 by 23—but anything past 4 by 5 is unnecessary unless you want the visual. Here's a practical shortcut most guides don't mention: if you dig out a trench so the bottom row of your portal sits at ground level and you leave the ground as the base, you only need 21 blocks instead of 23. The grass or dirt underneath counts as the missing bottom obsidian. The game doesn't care. It just validates the top three sides and the two vertical columns. I've used this trick dozens of times when I'm low on obsidian and don't feel like mining another vein. One thing to watch out for: the interior has to be completely clear. Air blocks only. If there's a single block of anything inside that rectangle—not even a flower, not even a torch—you'll light the portal and nothing happens. No purple swirls, no gateway, just a bunch of lit obsidian sitting there looking pointless. I learned this the hard way after spending roughly 45 minutes mining more obsidian because I couldn't figure out why my first three attempts failed. Turned out I'd placed a cobweb in the corner I'd forgotten about. Took two minutes to fix once I remembered to check.
Minecraft How To Make A Nether Portal
Activate it with flint and steel, then strike the inside air blocks from the bottom up. The flames travel vertically and fill the entire interior space. If you light just the bottom block, the portal still forms—the game registers it the same way. Some people think you have to chain-light each block individually. You don't. One spark works. You can also use lava. A lava bucket poured into the bottom center of the frame will ignite the portal on contact. This is actually more efficient early-game since you often have easier access to lava than flint and steel. Campfires and flames from candles work too, but they're tedious to position correctly and you'll end up breaking them to reposition. Stick to flint and steel or lava.
Obsidian Mining Reality
Obsidian takes about 40 seconds to mine with a diamond pickaxe. Netherite is faster at roughly 10 seconds. Anything below diamond—including gold, iron, stone—does absolutely nothing. The block simply won't break. This is a common trap for new players who spend hours trying to mine it with an iron pick and think they're doing something wrong. If you're building a portal before you have a diamond pickaxe, your options are limited. You can trade with a wandering trader for obsidian, though they only carry one or two at a time. You can use the Ender Pearl glitch to reach a Nether portal already in the world and transport obsidian back through it. Or you wait. It usually takes most players a few hours of regular gameplay before they have enough obsidian saved up and a diamond pick to spare. There's also the matter of how obsidian generates. Most of it sits in Nether fortress corridors and ruined portals. A ruined portal spawns with 14 already-placed obsidian blocks, which cuts your mining requirement nearly in half. They appear in every biome at various Y-levels, so it's worth checking the area around your spawn point. If you find one, you can collect the existing blocks and only need to place 9 more to complete a 4-by-5 frame.
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The Scale Matters More Than You Think
A standard 4-by-5 portal creates a 2-by-3 passable opening. That's roughly 6 square blocks of surface area. An 11-by-14 portal gives you a 9-by-12 opening, which is 108 square blocks. The bigger portal scales the Nether dimension differently. The standard 1:8 ratio still applies—you travel 8 blocks in the Nether for every 1 block you travel in the Overworld—but the larger frame makes navigation significantly easier because you have more room to move when you exit. Narrow 2-by-3 portals can be frustrating in crowded Nether biomes where you might get stuck against a wall on the other side. The real limitation with larger portals is time. Building a 23-by-23 frame requires 484 obsidian blocks. At roughly 40 seconds per block with a diamond pick, that's over 5 hours of pure mining time. Most players don't do this unless they're building a permanent transportation network. A single large portal is fine. Multiple large portals across a base is where the time investment really adds up.
Common Failures
Invalid shape is the biggest issue. The frame doesn't have to be perfectly rectangular in terms of block placement, but the four corners must exist and the vertical and horizontal edges must connect. If you leave a gap in the middle of a side, the game treats it as two separate incomplete frames and won't activate anything. I've seen players spend 20 minutes trying to figure out why their portal won't light when the problem was a single missing block in the middle of the top row. Lava mechanics can also cause problems. If you use lava to ignite the portal and there's any non-air block touching the lava source, the lava turns to cobblestone or obsidian and the portal never forms. Make sure the interior is clear before pouring. Using a lava bucket is reliable as long as you pour it directly into an empty interior space. There's also the issue of portal locking. When you enter a Nether portal, the game assigns a destination coordinate based on your Overworld position divided by 8. If you build two portals within the same 128-block radius in the Overworld, they'll both warp to the same Nether location. This is intentional behavior, not a bug. The workaround is to build your second portal at least 128 blocks away from the first in any direction. That forces the game to create a separate Nether coordinate for it. I ran into this when trying to set up a quick transit between two areas of my base and ended up teleporting back to the same spot three times before I realized the distance issue.
What Won't Work
Portals made with any block other than obsidian don't function. There's no alternative material. End portals use different blocks entirely and serve a completely separate purpose. If you're watching YouTube tutorials suggesting you can use blackstone or deepslate as a substitute, those videos are wrong. Obsidian is the only valid frame material, and there are no mods or settings in vanilla that change this. Water won't extinguish a lit Nether portal. Once activated, the purple particle effect persists regardless of nearby water sources. This is worth knowing because some players try to douse accidental portal activations and waste their time. It won't work. The portal stays lit until you break the frame blocks.
