Startup Flags Generator Tool Icon

Startup Flags Generator

Generate optimized Java startup flags (Aikar's Flags) to improve Minecraft server performance, stability, and memory usage.

Compatibility Alert

This generator generates flags configured specifically for Pterodactyl game panels.

Enter allocated memory in megabytes (e.g. 4GB = 4096, 8GB = 8192, 16GB = 16384)
The precise execution target file on your server volume directory structure (e.g. server.jar, paper.jar)

Generated Startup Command

Paste this entire block into the Startup Command variable field inside your Pterodactyl console page settings area.

java -Xms128M -Xmx7372M -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true -Dterminal.jline=false -Dterminal.ansi=true -Dlog4j2.formatMsgNoLookups=true $( [[ ! -f unix_args.txt ]] && printf %s "-jar server.jar" || printf %s "@unix_args.txt" )

Frequently Asked Questions

Learn more about Aikar's Java startup flags, garbage collection tuning, and memory configuration.

Aikar's Flags & GC Optimization

Aikar's Flags are fine-tuned Java Virtual Machine (JVM) start-up parameters tailored specifically for Minecraft servers. They optimize G1GC (G1 Garbage Collector) behavior, preventing noticeable tick pauses and lag spikes during heavy memory cleanup.
Log into your Pterodactyl server panel, select your server, navigate to Startup in the sidebar menu, and paste the generated string into the 'Startup Command' or 'Custom Java Flags' field.

RAM Allocation & Java Settings

Java applications require overhead memory for thread stacks, off-heap buffers, and garbage collection tasks. Reserving ~10% headroom prevents Linux Out-Of-Memory (OOM) killer from terminating your server container.
Yes! Ensure the filename entered in this generator matches the exact name of your server binary stored in your root directory (e.g. server.jar, paper.jar, or purpur.jar).