Building a Nether Portal in Minecraft is one of the most important milestones in the game. It unlocks access to the Nether dimension, where players can find rare resources, unique mobs, and critical materials such as Blaze Rods and Netherite components. However, before stepping through that purple portal, you need one essential material: obsidian. Understanding exactly how much obsidian you need — and why — ensures you gather the right amount without wasting time or resources.
TLDR: You need a minimum of 10 blocks of obsidian to build a functional Nether Portal in Minecraft. A full rectangular frame requires 14 blocks, but the four corner blocks are optional. The maximum usable portal size is much larger and requires significantly more obsidian. Always gather a few extra blocks in case of mistakes or future builds.
Minimum Obsidian Required for a Nether Portal
The smallest working Nether Portal requires 10 blocks of obsidian. Many players mistakenly believe you need 14 blocks because that completes the full rectangular frame. However, Minecraft mechanics allow you to omit the four corner blocks.
The minimum dimensions for a functional portal frame are:
- Height: 4 blocks
- Width: 5 blocks
This includes the frame. When removing the four corners, you save four blocks of obsidian.
The layout looks like this structurally:
While the corners are visually satisfying, they are not required for activation. As long as the vertical sides and top and bottom rows are intact, the portal will form when ignited.
Standard Portal: 14 Blocks of Obsidian
If you choose to build the complete rectangular frame, you will need 14 obsidian blocks. This includes:
- 4 blocks for the bottom
- 4 blocks for the top
- 3 blocks on each side (vertical pillars)
This configuration is the most common because:
- It looks symmetrical and clean
- It is easier for beginners to visualize
- It reduces the risk of design mistakes
Although it uses more materials, the additional four blocks are often worth the improved aesthetics.
Maximum Nether Portal Size
Minecraft also allows significantly larger portal designs. The maximum portal frame size is:
- 23 blocks tall
- 23 blocks wide
This means the largest possible portal uses over 80 blocks of obsidian, depending on the specific dimensions. Large portals are often built for decorative, multiplayer, or dramatic base entrances rather than necessity.
Important considerations for large portals:
- Any rectangular frame between minimum and maximum dimensions will work.
- The interior must remain empty.
- The frame must be entirely obsidian.
For survival gameplay, oversized portals are rarely practical due to the high cost of obsidian.
How to Calculate Obsidian for Any Portal Size
If you want a custom-sized portal, calculating the required obsidian is straightforward.
Formula:
(Width × 2) + (Height × 2) − 4
The minus 4 accounts for shared corner blocks.
Example:
- Width: 6 blocks
- Height: 8 blocks
(6 × 2) + (8 × 2) − 4 = 12 + 16 − 4 = 24 obsidian blocks
This formula helps prevent over-collection and is especially useful for large builds.
How to Obtain Obsidian
Obsidian forms when water flows over a lava source block. However, mining it requires specific tools. Without the correct pickaxe, the block either breaks too slowly or drops nothing.
You must use:
- Diamond Pickaxe
- Netherite Pickaxe
No other tool will successfully harvest obsidian.
Image not found in postmetaTool Comparison for Mining Obsidian
| Tool | Can Mine Obsidian? | Mining Speed | Durability | Best Use Case |
|---|---|---|---|---|
| Wooden Pickaxe | No | N/A | Low | Cannot mine obsidian |
| Stone Pickaxe | No | N/A | Medium | Cannot mine obsidian |
| Iron Pickaxe | No | N/A | Good | Cannot mine obsidian |
| Diamond Pickaxe | Yes | Slow | High | Standard choice |
| Netherite Pickaxe | Yes | Faster than diamond | Very High | Late game efficiency |
Even with a diamond pickaxe, mining a single block of obsidian takes about 9–10 seconds without enchantments. Using Efficiency enchantments significantly reduces this time.
Speeding Up the Collection Process
To gather 10–14 obsidian blocks efficiently:
- Bring a water bucket to control lava pools.
- Mine from the top layer downward to avoid falling into lava.
- Use Efficiency IV or V on your pickaxe.
- Carry multiple pickaxes if durability is low.
Adding the Unbreaking and Mending enchantments extends tool lifespan and reduces material costs long term.
Do You Always Need to Mine 10 Blocks?
Not necessarily. There are alternative methods to obtain obsidian or even complete portal frames:
- Ruined Portals: Naturally generated structures that can be repaired.
- Villager Trading: Some trades provide obsidian.
- Bartering with Piglins: Rare chance to receive obsidian.
Ruined portals are especially useful early in survival mode. You may only need a few additional blocks to complete one.
Common Mistakes When Building a Nether Portal
Players frequently waste obsidian due to simple errors. The most common include:
- Building the frame horizontally instead of vertically
- Incorrect interior dimensions
- Leaving gaps in the frame
- Using crying obsidian instead of standard obsidian
Crying obsidian cannot form a Nether Portal. This mistake is particularly common with ruined portal sites.
Igniting the Portal
Once the frame is complete, activation requires:
- Flint and Steel (flint + iron ingot)
- Or a fire charge
When ignited, the interior fills with a purple, animated field. If nothing happens, double-check:
- The frame dimensions
- That only regular obsidian was used
- That the interior space is clear
Should You Gather Extra Obsidian?
Yes. It is recommended to collect at least 14–16 blocks, even if you only plan to build the minimum 10-block portal. Reasons include:
- Accidental misplacement
- Future decorative upgrades
- Backup portal in the Nether
Remember that Nether travel can strand you if your portal is destroyed and you lack materials to rebuild.
Efficiency vs. Aesthetics: What Matters More?
From a purely functional standpoint, 10 blocks of obsidian are sufficient. However, many experienced players opt for the full 14-block frame or larger designs to integrate seamlessly into their base architecture.
Consider:
- If resources are scarce, build the minimum.
- If aesthetics matter, use the full frame.
- If building a permanent base portal, invest in stronger materials surrounding it.
Final Answer: How Much Obsidian Do You Need?
At its core, the answer is simple:
- Absolute minimum: 10 blocks
- Typical full frame: 14 blocks
- Large custom portal: 24 to 80+ blocks
For most survival players, aiming for 14 blocks is the safest and most practical approach. It balances efficiency, usability, and appearance without consuming excessive time.
Understanding Nether Portal mechanics prevents wasted materials, reduces early-game risk, and accelerates progression into one of Minecraft’s most resource-rich dimensions. With proper preparation and the right tools, gathering enough obsidian becomes a manageable — and worthwhile — investment.
