how much obsidian for a nether portal
Short answer: A standard functional Nether portal needs 10 obsidian blocks (corners optional); a fully-cornered rectangular frame uses 14 obsidian blocks.
Portal sizes and obsidian counts
- Minimum (functional) — 10 obsidian blocks: frame 4×5 with a 2×3 interior, corners omitted.
- Standard full frame — 14 obsidian blocks: same 4×5 outer size but including the four corner blocks.
- Larger portals — scale up to a maximum outer size of 23×23; obsidian required grows with the frame (maximum 88 blocks if you include all corners for a 23×23).
Why corners aren’t required
The game activates a portal as long as the rectangular ring of obsidian creates the 2×3 or larger interior space; the corner blocks are optional for functionality and are only aesthetic, so you can save four blocks by omitting them.
Quick building tips
- Use 10 blocks when you want to minimize mining; use 14 if you prefer a complete-looking frame.
- You need a flint-and-steel (or other fire source) to light the portal after building.
- You can craft obsidian by pouring water over lava source blocks, or mine naturally occurring obsidian with a diamond or netherite pickaxe.
Example counts table
| Portal Outer Size | Interior | Obsidian Needed |
|---|---|---|
| 4×5 (minimum functional) | 2×3 | 10 (corners omitted) |
| 4×5 (full frame) | 2×3 | 14 (corners included) |
| n×m (larger) | depends | Use formula or calculator; max 88 for 23×23 |
Calculation note
For a rectangular frame of outer width w and outer height h, excluding corners the minimal block count equals 2(w − 2) + 2(h − 2); adding the four corners gives +4. For the standard 4×5 outer frame that yields 10 (or 14 with corners).
Bottom note: Information gathered from public sources and game documentation.