Hosting Project Zomboid? Build 42's Server Perks vs B41 Woes

Hosting Project Zomboid? Build 42's Server Perks vs B41 Woes

Project Zomboid Server Requirements (Build 41 vs Build 42)

Small Group Hosting Guide – 2025 Edition

Quick Answer:

Hosting a small Project Zomboid server (for 2–8 players) doesn't require a supercomputer. In general, allocate ~4–6 GB of RAM and use a mid-tier 4-core CPU to keep things smooth. A good rule of thumb is ~2 GB base + 0.5 GB per player – so a 6-player server might use around 5 GB RAM. Build 42 hasn't raised hardware needs; in fact its optimizations improved multiplayer performance. Aim for at least a 10 Mbps upload connection for low-lag play.

Contents

Quick-Start Guide

If you're itching to get your Project Zomboid server running ASAP, this quick-start will guide you through the basic setup. This applies to both Build 41 (B41) and Build 42 (B42) servers. For troubleshooting common issues, see our server connection guide.

  1. Install the Dedicated Server files: In your Steam client, go to Library → Tools and search for "Project Zomboid Dedicated Server". Install it (about 5 GB).
  2. Launch the server for the first time: Find the server files (right-click Project Zomboid Dedicated Server in Steam → Properties → Local Files → Browse). Run the StartServer64.bat file. Set an admin password when prompted.
  3. Allow firewall access: Accept the Windows firewall prompt. For internet play, forward port 16261 UDP and a range (e.g., 16262-16266 UDP) on your router. For detailed troubleshooting, check our server error fixes guide.
  4. Configure server: After first-time setup, close the server. Launch the game, go to HOST → Manage Settings. Set server name, description, password, and memory allocation (2GB minimum, more for larger groups).
  5. Start the server: Either click Start in the in-game host interface or run StartServer64.bat again. The console will show "Server started" when ready.
  6. Connect to your server: Launch PZ, go to Join → LAN or Internet. If local, the server might be listed as 127.0.0.1. Otherwise, add it as a Favorite using your public IP. Default port is 16261.
  7. Share server info: Give your friends your public IP and server password. They'll connect via Join → Internet → Add.
  8. Keep it running: To stop the server, type 'save' then 'quit' in the console, or use the in-game Host "Stop" button.

For persistent use, consider running the server on a spare PC or a hosted service so it's online 24/7. For comprehensive server management, see our admin survival guide.

Server Hardware Requirements

RAM and Player Count

Memory is often the first concern when hosting a Project Zomboid server. Here's what you need to know:

Memory Formula: ~2 GB base + 0.5 GB per player

Example: A 6-player server needs approximately 5 GB RAM (2 + 0.5 × 6)

Players RAM (vanilla) RAM (modded) CPU Cores & Clock Network (Upload)
2–4 3–4 GB ~4 GB 2+ cores @ 2.5+ GHz â‰Ĩ 5 Mbps
5–8 5–6 GB 6–8 GB 4 cores @ 3+ GHz â‰Ĩ 10 Mbps
10–16 8–12 GB 12–16 GB 4–6 cores @ 3.5+ GHz â‰Ĩ 20 Mbps
20–32 16 GB+ 20 GB+ 6+ cores @ 4.5+ GHz â‰Ĩ 50 Mbps

Do not allocate more than ~80% of your system's RAM to the server. Leave headroom for the OS and other processes.

CPU Requirements

Project Zomboid's server is CPU-bound, especially with many entities (zombies) and players:

  • Single-thread performance matters - PZ primarily uses 1-2 cores heavily. A fast dual-core can outperform a slow 16-core.
  • For 2-8 players, even an older Intel i3/i5 (or AMD equivalent) can handle it, if not ultra-low-power.
  • A modern 4-core CPU (~3+ GHz base clock) is generally sufficient for small servers.
  • Build 42 is more CPU-efficient than Build 41 due to optimizations.

Network Requirements

Network bandwidth determines how much data the server can send/receive per second:

  • Per player bandwidth: ~5-10 KB/s normally, spiking to 20-50 KB/s during intense moments.
  • Upload speed requirement: At least 5-10 Mbps upload for a small server.
  • Latency: For best results, host the server physically near the players. PZ is playable with 100-150ms ping, but below 100ms is ideal.
  • Ports: Open UDP ports 16261 (primary) and 16262 (direct connect) for optimal performance.

Storage and OS

Project Zomboid's server isn't heavy on disk space:

  • Install size: ~5 GB
  • Save files: A few hundred MB with map exploration
  • SSD recommended for faster chunk loading and saving
  • Both Windows and Linux run PZ servers well

Build 41 vs Build 42 – Changes in Server Performance

Project Zomboid Build 42 is a major update that brings improvements without increasing hardware requirements. In fact, it introduces optimizations that make server hosting more robust and flexible.

Improvements in Build 42

  • Better server synchronization - Reduced latency and fewer desync issues
  • Direct Connect - Lower ping and improved throughput (from B41.78 onward)
  • Performance optimizations - "Way better in B42" according to user reports
  • Discord integration - Better server-Discord communication tools
  • Animal AI - New livestock features that don't heavily tax the server

Key Considerations

  • Not backwards compatible - B42 servers cannot be joined by B41 clients
  • Mod compatibility - B41 mods may need updates for B42. See our B42 mod guide
  • New content - Animals, crafting systems, expanded map areas
  • Save migration - Cannot directly convert B41 saves to B42
  • Config format - Similar to B41, most settings carry over

"Performance is way better in Build 42" — Community feedback from early adopters

In summary, Build 42 brings welcome improvements for server hosts:

  • Smoother, more stable multiplayer (less lag, better sync)
  • New official features (animals, etc.) without demanding more hardware
  • Better integration tools (Discord, etc.) to manage your community
  • No need to upgrade your server machine just for B42

Hosting Environments

You can run a Project Zomboid server on different platforms. Let's compare your options:

Windows Hosting (Home PC or Server)

Pros

  • Easiest for beginners
  • GUI tools for configuration
  • No additional hardware needed
  • Easiest to manage mods

Cons

  • Consumes resources on your PC
  • Windows uses more RAM for OS
  • PC must stay on 24/7 for persistent server
  • Background Windows updates can cause lag

Windows-specific tips:

  • Service/Auto-start: Create a scheduled task or Windows Service for StartServer64.bat to start on boot
  • Firewall: Ensure Windows Defender Firewall allows java.exe or specific ports
  • Performance: Set power plan to high performance to avoid CPU downclocking
  • Dual use: For ~4 players, hosting and playing on the same PC works fine with decent hardware

Server Configuration and Administration

Key Config Files

All the server's settings are stored in the Zomboid/Server directory:

servertest_users.db — Database containing whitelisted users and their data

Important Settings in servertest.ini

# Basic server identity
Public=true               # Show in public list?
PublicName=My PZ Server   # Server name in browser
DefaultPort=16261         # Main server port
ServerPassword=           # Password to join (blank = none)

# Player settings
Open=true                 # If false, only whitelisted users can join
MaxPlayers=8              # Maximum concurrent players
PVP=false                 # Enable player vs player
PauseEmpty=true           # Pause when no players online

# Mod configuration
Mods=ModID1;ModID2;       # List of mod IDs to load
WorkshopItems=2392709985;2392709983  # Workshop file IDs

# Advanced
UPnP=true                 # Auto port forwarding
RCONPort=27015            # Remote console port
RCONPassword=             # Remote console password
HoursForLootRespawn=0     # Hours before loot respawns (0 = never)
HoursForZombiesRespawn=0  # Hours before zombies respawn

Admin Commands

As an admin, you can use these commands in-game (prefix with /) or in the server console:

/help

Lists all available commands

/save

Forces the server to save immediately

/players

Shows a list of connected players

/grantadmin "username"

Gives admin rights to a user

/teleport "player1" "player2"

Teleports player1 to player2

/adduser "username" "password"

Adds a user to whitelist

/banuser "username"

Bans a user from the server

/godmode "username"

Toggles invulnerability for a player

Whitelist and Access Control

For a small group server, you'll typically use one of these approaches:

Server Password Only

  • Set ServerPassword in servertest.ini
  • Set Open=true so anyone with password can join
  • Simple but less secure
  • Best for casual friend groups

Whitelist with Accounts

  • Set Open=false in servertest.ini
  • Use /adduser to create accounts for friends
  • More secure, with personalized logins
  • Character data tied to specific usernames

Backup and World Management

  • Backup: Copy the Saves/Multiplayer/servertest folder while server is offline
  • Hard Reset: Delete the save folder or change ServerName to generate a fresh world
  • Soft Reset: Resets world but keeps character data (specialized, requires launch in "softreset" mode)

Mods & Performance

Mods can greatly enhance your Project Zomboid experience but may impact server performance. Here's how to approach mods for a small server:

Lightweight vs Heavy Mods

Lightweight Mods

Characteristics:

  • Simple items or tweaks
  • Small file size (tens of MB)
  • Minimal performance impact

Examples:

  • Zed Removal
  • Quality of Life crafting mods
  • Small map additions

Heavy Mods

Characteristics:

  • Large maps or expansions
  • Many new items/textures
  • Complex AI or systems

Examples:

  • Brita's Weapons Pack
  • Hydrocraft
  • Raven Creek (large map)
  • NPC mods (pre-B42)

Performance-Friendly Mods for Small Groups

  • Authentic Z (outfits, backpacks)
  • Better Trailers
  • Skill Recovery Journal
  • Sleep Needed
  • Nocturnal Zombies
  • Vehicle Sound Overhaul
  • More Builds (furniture)
  • True Actions (animations)

Mods to Use With Caution

These mods can significantly impact server performance:

  • Brita's Armor/Guns - Can cause lag if not configured properly
  • Hydrocraft - Many items can increase RAM usage
  • Mass Zombie Spawn mods - Heavy on CPU due to AI calculations
  • Multiple large map mods - Increases RAM usage and world size

Managing Mods on Your Server

  • Create a Workshop Collection - Share with your friends so they can subscribe easily
  • Check Load Order - Required mods (dependencies) should appear earlier in the Mods list
  • Monitor Logs - Red errors about missing items may indicate mod issues
  • Schedule Restarts - When mods update, restart the server so everyone has the same version
  • Limit Adding/Removing Mods Mid-game - Changes can cause issues with existing saves

Performance Optimization Tips

Memory Management

  • Allocate sufficient RAM (see formula above)
  • Monitor usage with Task Manager or htop
  • Restart server periodically to clear memory
  • Limit total mods to what you actually need

Reduce Server Load

  • Use PauseEmpty=true if not running 24/7
  • Reduce zombie count in high-traffic areas
  • Set reasonable corpse/item cleanup times
  • Avoid extremely high loot settings

Network Optimization

  • Ensure direct connect port (16262) is open
  • Host server physically close to players
  • Close unnecessary programs using bandwidth
  • Consider QoS settings on your router

Frequently Asked Questions

How much RAM do I need for a Project Zomboid server?

It depends on player count and mods. As a rule, allocate 2 GB plus about 0.5 GB for each player slot. So for a 4-player server, ~4 GB is fine; for 8 players, ~6 GB; for 10+ players, 8 GB or more. If you use big mods or maps, add an extra 1-2 GB cushion.

Small co-op games (2-3 people) have run on even 2-3 GB, but 4 GB is recommended to be safe. Remember, more RAM won't necessarily boost performance after a point – it just prevents memory-related crashes.

Can I host a 5-player modded Project Zomboid server on my PC?

Yes, if your PC meets the specs. For 5 players with mods, you'll want around 6 GB RAM allocated and a decent CPU (e.g. a quad-core 3+ GHz). Most gaming PCs from the last 5-7 years qualify.

The key is your internet connection – ensure you have at least ~10 Mbps upload speed so all players have low ping. If you're also playing the game on the same PC, make sure the CPU/GPU can handle both the server and client.

Does Build 42 require better hardware than Build 41 for servers?

No – Build 42's server requirements are roughly the same as Build 41, and some aspects are even improved. The devs optimized multiplayer in Build 42, resulting in better performance per hardware spec (less lag at high load).

In other words, if your machine ran a Build 41 server adequately, it will run Build 42 as well or better. Build 42 adds new content (animals, more crafting) but those don't significantly increase CPU or RAM usage in vanilla.

One caveat: Build 42 is a newer build, so ensure any mods are updated, as outdated mods can cause issues that feel like performance problems.

How do I host a Project Zomboid Build 42 server on a Linux headless host?

Hosting B42 on a headless Linux follows these basic steps:

  1. Install the server files using SteamCMD (app ID 380870)
  2. Run the server with StartServer64.sh (make it executable with chmod +x)
  3. Edit servertest.ini for your settings
  4. Open ports on your Linux firewall (ufw allow 16261/udp etc.)
  5. Use screen or tmux to keep the server running after logout

No graphical interface is needed – all config can be done via text files. Headless Linux is a great way to host PZ 24/7 with low overhead.

What can I do to reduce lag on my Project Zomboid server?

To reduce lag, try these strategies:

  • Allocate sufficient RAM - Ensure you're not running out of memory
  • Use the direct connect port - Make sure port 16262 is open
  • Reduce zombie count - Massive hordes = heavy CPU load
  • Restart periodically - Clear accumulated memory issues
  • Enable PauseEmpty - Reduces workload when no one is online
  • Clean up corpses and loot - Set reasonable HoursForCorpseRemoval
  • Identify problematic mods - Some mods cause more lag than others

Check your server's ping readouts – if ping is high for everyone, it's network; if ping is low but things still lag, it's server CPU/RAM.

Are there any specific server mods or tools you recommend?

For ease of management, consider:

  • Discord integration - The built-in Discord integration in B42 is great
  • Server Save Manager - Tools for auto-saves and backups
  • Admin tools UIs - GUI for common admin tasks
  • PZ Server Web Map - Generate a live web map of your server (advanced)

Hosting a Project Zomboid server for you and your friends is extremely rewarding – nothing beats those emergent stories you get in a persistent world you manage!