Nether Portal Guide — The 1:8 Ratio and Linking Portals Correctly

The 1:8 ratio, stated exactly

Every Nether trip starts with one fact: horizontal coordinates and distances in the Nether are proportional to the Overworld at a ratio of 1:8. For any Overworld position (X, Y, Z), the matching Nether position is (floor(X ÷ 8), Y, floor(Z ÷ 8)). Going the other way, a Nether position (X, Y, Z) maps to the Overworld as (X × 8, Y, Z × 8). The division rounds toward zero, which only changes anything for negative coordinates: a base at X = 640 sits at Nether X = 80, and a base at X = −1280 sits at Nether X = -160.

The one axis that never scales is height. The 1:8 ratio applies to X and Z only — your Y coordinate is carried across unchanged. That is why a Nether tunnel built at Y = 12 drops you out 12 blocks above the Overworld floor, deep underground, while one built at Y = 64 arrives at Y = 64. Match the Nether-side Y to the Overworld Y you actually want to stand at — usually Y 55–70 for a surface base — and the exit lands where you expect.

Converting Overworld coordinates to Nether coordinates

The conversion is one division per horizontal axis. Divide the Overworld X by 8, divide the Overworld Z by 8, and leave Y alone. Both divisions round toward zero, so a coordinate of 999 becomes Nether X = 124 rather than 125. To reverse it, multiply by 8 — that is literally the arithmetic the game performs when you step back through the portal.

How portal linking actually picks your exit

The ratio decides where the game looks; it does not decide where you come out. When you step through a portal, the game converts your position and then searches for an existing portal near the converted coordinate. That search is asymmetric, and the two radii are the numbers most guides get wrong.

If an active portal sits inside that area you arrive at it; otherwise the game creates a new one at or near the converted coordinate. A destination portal is only generated when an entity passes through and there is no other active portal within 128 blocks of the matching coordinate. The narrow 16-block radius on the Nether side was deliberate — the 1.16.2 update cut it from 128 blocks to 16 specifically so it would match the 1:8 scale, and that change is why a badly placed second portal now collides far more often than it used to.

Keeping two portals from fighting over one exit

Because the Nether-side search radius is only 16 blocks, two Overworld portals whose Nether coordinates fall within 16 blocks of each other will share the same Nether-side exit. You build two portals and the game quietly routes both of them to one — the classic “I built a second portal and it dumped me back in my own tunnel” report.

16 Nether blocks equals 128 Overworld blocks, so the practical rule is simple: keep two Overworld portals at least 128 blocks apart, or build the Nether side at the coordinate you actually calculated for it. The safest workflow is to build the Nether portal yourself at (floor(X ÷ 8), Y, floor(Z ÷ 8)) for the Overworld location you are travelling between. Then both ends agree and no third portal quietly appears.

The reverse situation — an exit portal being forced — happens when you step through and nothing is found within range. The game then builds a portal at or near the target coordinates, constraining Y to between 70 and ten below the world height (118 in the Nether, 310 in the Overworld), and creates a small 2 × 3 obsidian platform with three blocks of air above it. That is the lone platform players occasionally surface on in the middle of nowhere, and it is why a purpose-built portal beats a blind one every time.

Teleport delay, cooldown and how long the far side stays loaded

Timing is part of the maths too. A player standing in a portal block is taken to the other dimension after 80 game ticks (4 seconds) in Survival, or a single tick in Creative, and can step out before the animation finishes to cancel the trip. Once on the other side, a non-player entity cannot use any Nether portal again for 300 game ticks (15 seconds); minecarts, boats and projectiles were later given much shorter cooldowns of 10 ticks (0.5 seconds) and 2 ticks (0.1 seconds) respectively.

The chunks around a portal stay loaded for 15 seconds after a pass, and that timer refreshes every time an entity crosses — the basis of the “chunk loader” trick that keeps a farm running while you are away. It also cuts the other way: a portal pair you are actively shuttling through keeps both sides loaded, which costs server performance if you build many of them.

Three worked examples

Example 1 — converting a base. Your Overworld base sits at (640, 64, -1280). The Nether coordinates are floor(640 ÷ 8) = 80 and floor(-1280 ÷ 8) = -160, with Y unchanged at 64. Build the Nether portal at (80, 64, -160) and the two ends line up exactly — no forced portal, no surprise platform.

Example 2 — how short a trip becomes. A 3,000-block Overworld journey is 3,000 ÷ 8 = 375 Nether blocks — a few minutes of tunnel instead of a full inventory of boats. The “Subspace Bubble” advancement asks for 7,000 blocks of Overworld travel, which is 7,000 ÷ 8 = 875 Nether blocks; a single highway under a thousand blocks long satisfies the whole requirement.

Example 3 — obsidian for a frame. The smallest valid frame is 4×5 exterior (a 2×3 opening) and needs 10 obsidian with the four corners omitted, or 14 if you build the corners. The largest is 23×23 exterior (a 21×21 opening), costing 88 obsidian with the corners and 84 without. Portals the game creates for you always include the corners, which is where the widely quoted “4 spare obsidian” comes from.

Frame sizes and what they cost

A frame is a vertical rectangle of obsidian: never horizontal, unlike an end portal. Any rectangle from 4×5 to 23×23 works, the corners are optional, and adjacent portals can share obsidian blocks. Light the inside with flint and steel (or a fire charge, a fireball, or a natural fire spread) to activate it.

A minimum 10-obsidian frame is enough for two-way travel and is the cheapest way to link a pair; the maximum 23×23 frame is a build statement rather than a functional upgrade, since a larger opening does not change the linking maths. What matters for travel is where the frame is, not how big it is.

Common mistakes that break a portal network

• Building the second portal wherever you happen to exit. That spot becomes the paired end whether you meant it to or not. Build at the calculated Nether coordinate instead and the pairing is under your control.
• Forgetting that Y does not scale. A tunnel at Nether Y = 12 comes out deep underground. Set the Nether Y to the Overworld height you want before you dig.
• Two Overworld portals closer than 128 blocks apart. Their Nether ends fall inside the 16-block search radius and share one exit. Space them out or merge the trip into one portal.
• Assuming Bedrock links like Java. On Bedrock both directions search 128 blocks, so the 16-block rule above does not apply and portals collide under different spacing.
• Leaving the return portal unlit. If the far-side portal goes out — a ghast fireball is the usual culprit — the next trip through may force a brand new portal. Carry flint and steel and relight it.
• Expecting the ratio to shorten the walk automatically. The 1:8 compression only pays off if you actually build the Nether-side path; the portal alone moves you, it does not dig the highway for you.

Sources and standards

FAQ