The Tool Desk
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What you need before building
A Nether portal is a vertical obsidian frame that creates portal blocks in its empty center when ignited. The basic construction and ignition process is shared across routine Java and Bedrock play, although technical block-state and axis details differ between editions.
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- Regular obsidian: enough for the frame you choose. Do not substitute crying obsidian for the frame.
- Flint and steel: the reusable, simplest ignition tool.
- Fire charge: a single-use alternative that can also light a Nether portal.
- A suitable site: clear space for the frame, a nonflammable area where practical, and room to protect the arrival point on the other side.
Choose the site before placing blocks. A portal can generate an arrival point in a hazardous location, so leave enough room to build a small landing platform or enclosure after you arrive.
Portal frame sizes and obsidian cost
The frame must be an upright rectangle. Valid outer dimensions run from 4×5 blocks through 23×23 blocks. The four corner blocks are optional for an operational frame, which is why the minimum economical design uses fewer blocks than a completely filled rectangle.
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| Frame design | Outer dimensions | Obsidian required | Use case |
|---|---|---|---|
| Minimum, cornerless | 4×5 | 10 | Lowest material cost while retaining a valid portal frame |
| Minimum, full corners | 4×5 | 14 | Simple rectangular outline with every corner filled |
| Larger frame | Up to 23×23 | Depends on the selected dimensions | More visual height or width while staying within the documented maximum |
For a 10-obsidian frame, omit one block at each corner. Temporary building blocks can support the top corners while you assemble the sides and top; remove those temporary blocks before ignition so the opening is clear.
How to build a Nether portal
1. Mark the footprint
On level ground or another stable surface, mark a rectangle at least four blocks wide and five blocks tall. “Wide” and “tall” refer to the outside dimensions of the frame, not the empty center. Keep the rectangle vertical rather than laying it flat.
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2. Place the obsidian sides
Build the two vertical columns first. Each column must be part of the same upright rectangle. If you are making the economical design, leave the four corner positions empty; the side columns and top and bottom bars still define the frame.
3. Add the bottom and top bars
Connect the columns with an obsidian bar at the bottom and another at the top. Check that the outside dimensions meet the 4×5 minimum and do not exceed 23×23. A frame made from ordinary building blocks, or one that is too small, will not activate as a Nether portal.
4. Clear the opening completely
Remove every block from the rectangle’s interior before attempting to light it. Portal blocks are created in that opening only after a successful ignition attempt, so an obstruction can prevent activation.
5. Inspect the material
Every frame block should be regular obsidian. Crying obsidian is not a valid substitute for this frame, even though it looks similar and can appear in ruined-portal structures.
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Flint and steel
- Stand on the Overworld side of the frame.
- Use flint and steel on the inside near the lower part of the frame, targeting the empty opening rather than the outside of the structure.
- Wait for the portal blocks to appear in the opening. Once they form, the frame is active.
Flint and steel is reusable, making it the practical default when you expect to build or relight portals repeatedly.
Fire charge
A fire charge can ignite a Nether portal when flint and steel is unavailable. It is single-use, so treat it as a backup and carry more than one if you are relying on it for an expedition.
If the first ignition fails
Do not rebuild immediately. Recheck the frame’s orientation, dimensions, material, interior, and ignition position in that order. The common causes are an upright rectangle that is below the minimum size, crying obsidian in the frame, a block left inside the opening, or fire placed outside rather than inside the lower frame area.
Prepare before entering the Nether
Activation does not make the destination safe. Before stepping through, make sure you can survive the first moments on the other side. The achievement guidance for a first trip emphasizes building a portal or repairing a ruined one and returning immediately if you are not prepared for the Nether.
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1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errors- Keep the Overworld side accessible so you can retreat without dismantling anything.
- Bring enough supplies for an unexpected arrival location rather than assuming the Nether side will be beside a convenient base.
- After arrival, secure the landing area with a platform or enclosure and enough lighting to see hazards.
- Record both portals’ coordinates before making long trips, especially if you intend to create a permanent route.
An exposed portal can leave you vulnerable as soon as the loading transition ends. A small protected room around the frame gives you time to orient yourself and prevents an accidental step off a ledge.
How portal linking works
The game uses an 8:1 horizontal coordinate relationship between the Overworld and Nether. Convert X and Z; do not convert Y with the same rule. For an Overworld-to-Nether plan, divide the Overworld X and Z by 8. For a Nether-to-Overworld plan, multiply the Nether X and Z by 8.
| Starting dimension | Coordinates to record | Conversion for the other dimension |
|---|---|---|
| Overworld | X, Y, Z | Nether target: X ÷ 8 and Z ÷ 8 |
| Nether | X, Y, Z | Overworld target: X × 8 and Z × 8 |
Example: Overworld to Nether
If the Overworld frame is at X 800, Y 70, Z −240, divide only the horizontal values. The planned Nether location is approximately X 100, Z −30; retain the recorded Y as a reference rather than applying an 8:1 calculation to it.
Example: Nether to Overworld
If a Nether frame is at X −75, Y 64, Z 40, multiply X and Z by 8. The corresponding Overworld target is approximately X −600, Z 320.
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Build at the converted location
- Write down the source portal’s exact X, Y, and Z.
- Calculate the target X and Z with the appropriate divide-by-8 or multiply-by-8 operation.
- Travel to the target dimension and build a second upright frame as close as practical to those horizontal coordinates.
- Clear the opening and ignite the new frame.
- Test both directions, noting the actual coordinates of each frame after the game finishes its portal search.
The conversion is a planning method, not a guarantee that the frames will occupy identical Y values or that every trip will use the frame you intended. The game also considers available portal locations and nearby portals when selecting a destination.
Why a portal may link to the wrong place
The target is too far from the converted X/Z
Compare the actual coordinates of both frames with the converted target. If the Nether frame is substantially away from the planned X/Z location, move or rebuild it closer and test again.
Another portal is competing for the route
Duplicate or nearby portals can be selected instead of the one you expected. Record every frame in the area, then remove portals that should not participate in the route. Reignite the remaining frame after clearing the competition.
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The portal was generated rather than preplanned
When you enter through a single portal and let the game create the destination, the generated frame may not be where a carefully planned transport line would place it. Use the actual generated coordinates as your new reference, then build a replacement frame near the converted X/Z target if predictable travel is more important than keeping the first location.
Y coordinates were treated as an 8:1 value
The documented conversion applies to horizontal X and Z. Matching or scaling Y alone does not guarantee a link, because destination selection also depends on available portal locations and nearby frames.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Troubleshoot a portal that will not light
| Symptom or check | Correction |
|---|---|
| Frame is lying flat or is not an upright rectangle | Rebuild it vertically as a rectangle. |
| Outer dimensions are below 4×5 | Expand the frame to at least 4 blocks wide and 5 blocks tall. |
| Frame is larger than the documented limit | Reduce it to no more than 23×23 outer blocks. |
| Crying obsidian is present | Replace it with regular obsidian. |
| A block remains in the opening | Remove every interior obstruction, then try again. |
| Fire was placed outside the frame | Use flint and steel or a fire charge on the inside near the lower frame. |
| Ignition tool is unavailable | Use a fire charge as the single-use alternative. |
After correcting a fault, perform a fresh ignition attempt. Portal blocks do not need to be placed by hand; they appear in the empty center when the frame accepts the ignition.
Java and Bedrock considerations
The frame dimensions, empty opening, and ignition sequence described here are the practical shared steps. Technical block-state documentation distinguishes Java and Bedrock portal-axis states, so record your edition when diagnosing orientation-specific behavior or documenting a build for someone else. If a highly technical explanation conflicts with what you see in game, verify the exact edition and game version before changing a working frame.
Edition differences are especially relevant when discussing the internal axis state of portal blocks. They do not change the basic checklist: regular obsidian, upright rectangle, valid dimensions, empty interior, and ignition from inside the lower frame area.
Choosing a frame and ignition method
| Decision | Option | Trade-off |
|---|---|---|
| Minimize obsidian use | 10-block cornerless 4×5 frame | Requires careful corner support while building |
| Use a visually complete outline | 14-block 4×5 frame with corners | Costs four additional obsidian blocks |
| Relight repeatedly | Flint and steel | Reusable ignition tool |
| Ignite without flint and steel | Fire charge | Single-use item |
| Prioritize predictable travel | Prebuild near converted 8:1 X/Z coordinates | Requires recording coordinates and clearing competing portals |
| Prioritize speed | Enter through one frame and use the generated destination | Arrival location may require later adjustment |
A reliable maintenance routine
Once two portals are working, keep a short record with the dimension and X, Y, and Z for each frame. If a route changes, update the record rather than relying on memory. When a trip starts using an unexpected destination, inspect the actual frame coordinates first; rebuilding random frames without checking coordinates can create more competing destinations.
- Stand at the frame and record its coordinates.
- Check the other dimension’s frame against the 8:1 horizontal target.
- Remove duplicate frames that are not part of the intended route.
- Move or rebuild the destination frame closer to the converted X/Z location.
- Test the route in both directions from a protected landing area.
This process separates two different problems: an inactive frame needs a construction or ignition fix, while an active frame that sends you elsewhere needs coordinate and nearby-portal management.
Final checklist
- Frame is a vertical rectangle between 4×5 and 23×23 outer blocks.
- Frame uses regular obsidian.
- Interior is empty before ignition.
- Flint and steel or a fire charge is used inside near the lower frame.
- Arrival area has a protected platform or enclosure.
- Source portal coordinates are recorded.
- Nether and Overworld X/Z values are planned with the 8:1 conversion.
- Nearby duplicate portals are removed when they interfere with routing.
With those checks complete, a cornerless 10-obsidian frame is enough for a working portal, while coordinate planning and a protected landing area turn it into a dependable transport link.
Quick Recap
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