How to allocate more RAM to Lunar Client

Lunar Client lets you set how much of your computer's memory it can use through its built-in launcher settings. Open Lunar Client, click the gear icon in the top right, then select "Game Settings." Scroll down to find "Memory" or "RAM Allocation" and use the slider or number field to increase it. The amount you can safely give depends on your total system RAM — most players see better performance with 4 to 8 gigabytes allocated, but your computer needs to keep some RAM free for Windows or macOS to run.

After you change the setting, close and reopen Lunar Client completely for the change to take effect. Launch Minecraft and play for a few minutes to see if the lag or stuttering improves. If crashes continue, your computer may not have enough total RAM, or another program running in the background is using memory you thought was free.

Key Takeaways

  • Lunar Client's launcher has a built-in RAM slider in Game Settings that you adjust without touching any files or code.
  • Allocating more RAM helps when you see lag spikes, low frame rates, or crashes that happen after playing for 10 to 30 minutes.
  • Never allocate more than half your total system RAM to Minecraft, because your operating system needs the rest to function.
  • If you have less than 8 gigabytes of total RAM on your computer, allocating more to Lunar Client may make other programs run slower instead of fixing Minecraft.

Check how much total RAM your computer has

Before you increase Lunar Client's allocation, find out how much RAM your computer actually has. On Windows, right-click "This PC" or "My Computer" on your desktop, click "Properties," and look for "Installed RAM" — it will show a number like "16 GB" or "8 GB." On Mac, click the Apple menu, select "About This Mac," and read the "Memory" line.

Write down this number. As a rule, never allocate more than half of it to Minecraft. If your computer has 8 gigabytes total, cap Lunar Client at 4 gigabytes. If it has 16 gigabytes, you can safely go up to 8. This leaves enough RAM for your operating system, your web browser, Discord, and other programs you run while playing.

Open Lunar Client's Game Settings

Launch Lunar Client from your desktop or Start menu. Wait for the launcher window to fully load — this takes 10 to 20 seconds on most computers. In the top right corner of the launcher, you will see a gear icon. Click it to open settings.

Look for a tab or section labeled "Game Settings" or sometimes just "Settings." This is different from "Launcher Settings" — you want the one that controls how Minecraft itself runs. Scroll down the list until you see "Memory," "RAM," "JVM Arguments," or "Allocated Memory." The exact name varies slightly depending on your Lunar Client version, but it will be in this section.

Adjust the RAM slider or enter a number

Most versions of Lunar Client show a slider you can drag left or right to increase or decrease RAM. Drag it to your target amount — for example, if your computer has 16 gigabytes total, drag it to 8. Some versions let you type a number directly into a box instead. Enter the amount in gigabytes, like "6" or "8" (not "6000" or "8192" — Lunar Client handles the conversion).

After you set the number, look for a "Save" or "Apply" button and click it. If you do not see a button, the setting usually saves automatically when you close the settings window. Close Lunar Client completely — do not just minimize it — and wait 5 seconds before opening it again. This forces the launcher to load with your new RAM setting.

Test the change and watch for improvement

Open Lunar Client again and launch Minecraft. Create a new world or join a server you play on regularly. Play for at least 10 to 15 minutes, paying attention to frame rate and stuttering. If you were seeing lag spikes every 30 seconds, they should happen less often or stop entirely. If crashes were happening after 20 minutes of play, the game should stay stable longer.

If you still see lag or crashes after increasing RAM, close Minecraft and check what other programs are running. Open Task Manager on Windows (press Ctrl + Shift + Esc) or Activity Monitor on Mac (open Spotlight, type "Activity Monitor," and press Enter). Look at the "Memory" column to see if Chrome, Discord, or another program is using several gigabytes. Close unnecessary programs and try Minecraft again.

When more RAM will not fix the problem

Lag and crashes have different causes, and more RAM only fixes some of them. If your frame rate is low but steady — you get 30 frames per second instead of 60 — the problem is usually your graphics card or CPU, not RAM. More RAM will not help. If the game crashes with an error message about "out of memory," then RAM allocation is the issue. If it crashes with no message or a different error, the problem is usually a mod conflict, a corrupted world file, or a driver update.

If your computer has only 4 or 6 gigabytes of total RAM, allocating more to Lunar Client may actually make things worse. Your operating system needs at least 2 to 3 gigabytes to run smoothly. If you give Minecraft 4 gigabytes on a 6-gigabyte computer, Windows will slow down dramatically, and you may see more lag, not less. In this case, closing other programs before you play is more effective than increasing the allocation.

Frequently Asked Questions

How much RAM should I allocate if I have 8 gigabytes total?

Start with 4 gigabytes. This leaves 4 gigabytes for Windows, your web browser, and other programs. If you see lag after 30 minutes of play, try 5 gigabytes, but do not go higher — your computer needs at least 2 to 3 gigabytes free to stay responsive.

Will allocating more RAM make Minecraft run faster?

It will reduce lag spikes and crashes caused by running out of memory, but it will not increase your frame rate if your graphics card or CPU is the bottleneck. If you get a steady 40 frames per second, more RAM will not push it to 60. If you get 60 frames per second but it drops to 20 every few minutes, more RAM may fix those drops.

What if I allocate too much RAM and Minecraft crashes?

Close Lunar Client, reopen it, and lower the allocation by 1 or 2 gigabytes. You likely allocated more than your computer could spare. Save the new setting and restart Minecraft. If crashes continue, your computer may not have enough total RAM for the mods or world you are playing.

Do I need to change RAM allocation for every modpack?

Most modpacks work fine with the same allocation, but large packs with 100+ mods may need more. If you switch to a heavy modpack and see crashes, try increasing the allocation by 1 or 2 gigabytes. Vanilla Minecraft and small modpacks usually run well on 4 gigabytes.

Can I allocate RAM to Lunar Client on a Mac?

Yes, the process is identical. Open Lunar Client, click the gear icon, go to Game Settings, find Memory, and adjust the slider. The same rules apply — never allocate more than half your total system RAM, and leave at least 2 to 3 gigabytes free for macOS.