Best Raspberry Pi Homelab Project for 24/7 Use

The single best Raspberry Pi project to leave running 24/7 in a homelab is a Pi-hole network-wide ad blocker combined with a lightweight DNS server. You install it once, point your router at it, and it silently filters ads and trackers for every device on your network while using under 1W of power and requiring almost zero maintenance.

Formula

Energy (kWh) = (time in hours × power in watts) / 1000. Daily cost = energy × electricity rate. The variables are: t = time the Pi runs in hours (default 24), w = average power draw in watts (default 3W for a Pi 4 under light load), and the electricity rate you pay per kWh (default $0.15, adjust to your local rate).

Worked Example

Using the defaults: t = 24 hours, w = 3 watts. Energy = (24 × 3) / 1000 = 0.072 kWh per day. Daily cost = 0.072 × 0.15 = $0.0108, about one cent per day. Over a year that’s roughly $3.94. A Pi 4 idles at about 2.7W and uses 3–4W under light DNS load, so these numbers are realistic for a Pi-hole setup.

Why Pi-hole Is the Ideal 24/7 Project

Pi-hole is a DNS sinkhole: it intercepts DNS queries from your devices and blocks requests to known ad and tracking domains. It runs on any Raspberry Pi (Zero 2 W, 3B+, 4B, or 5), uses very little RAM, and writes almost nothing to the SD card after boot. Unlike a media server or a game server, it doesn’t need constant attention, doesn’t generate heat, and doesn’t require a large storage drive. Once configured, it just runs.

It also gives you a useful dashboard: you can see how many queries are blocked, which devices are making the most requests, and which domains are being queried. You can whitelist false positives and blacklist custom domains. It’s a project that teaches you about DNS, DHCP, and network fundamentals while delivering a tangible benefit to every device on your network.

How It Works

When you set your router’s DNS to the Pi’s IP address, every device on your network sends its DNS queries to the Pi instead of to your ISP’s DNS. Pi-hole checks each query against a blocklist (default: StevenBlack’s hosts list plus a few others). If the domain is on the list, Pi-hole returns a null answer (0.0.0.0) and the device can’t connect to that ad server. If it’s not blocked, Pi-hole forwards the query to a public DNS resolver (like Cloudflare or Google) and returns the answer.

You can also enable DHCP on Pi-hole to replace your router’s DHCP server, which makes it easier to assign the Pi as the DNS server to every client. But the simplest setup is to change the DNS settings in your router’s admin page. That way, even devices that don’t let you change DNS (like smart TVs or IoT gadgets) are covered.

Hardware and Setup Choices

For a 24/7 Pi-hole, you don’t need a Pi 5. A Raspberry Pi Zero 2 W is enough, but its single-core CPU and Wi-Fi can feel sluggish when you also run other services. A Pi 3B+ or Pi 4B with 2GB RAM is the sweet spot: it’s cheap, runs cool, and has enough power to also run a WireGuard VPN, a small Node-RED instance, or a Uptime Kuma monitor. If you already have a Pi 4, use it; if you’re buying new, a Pi 5 with 4GB is overkill but future-proof if you plan to add more services later.

For storage, use a good-quality microSD card (A2 class) or, better, an SSD via USB if you plan to run other services. Pi-hole itself writes very little, but a flaky SD card is the most common cause of downtime. Set up log rotation (Pi-hole does this by default) and consider using the log2ram utility to reduce writes.

Power: use an official Raspberry Pi power supply or a high-quality 5V/3A adapter. A cheap phone charger may cause undervoltage warnings and random reboots.

Common Problems and Fixes

• No queries showing in the dashboard: Your router may still be using its own DNS. Check that the router’s DNS is set to the Pi’s IP, and that the Pi has a static IP (set via DHCP reservation or in /etc/dhcpcd.conf).
• Some ads still appear: Some sites serve ads from the same domain as content (e.g., YouTube). Pi-hole can’t block those without breaking the site. Also, some apps use hardcoded IPs or DNS-over-HTTPS, which bypass Pi-hole.
• Pi keeps rebooting: Check the power supply and the SD card. Run vcgencmd get_throttled to see if undervoltage occurred.
• DNS leaks on Android: Android 9+ uses private DNS by default. You need to set Private DNS to “Offâ€� or point it to your Pi-hole (if you have a domain).
• Router doesn’t let you change DNS: You can either enable DHCP on Pi-hole and disable it on the router, or set DNS manually on each device.

Comparison to Other 24/7 Projects

Other popular 24/7 Pi projects include:

• Home Assistant: Smart home hub, but it’s heavier, requires more RAM, and often needs a Zigbee/USB dongle. It’s more of a full-time job.
• PiVPN (WireGuard): Great for secure remote access, but it only helps when you’re away from home. It’s a perfect companion to Pi-hole, but not a primary project.
• Network-wide ad blocker alternatives: AdGuard Home is a similar DNS sinkhole with a nicer UI and multi-user support. It runs fine on a Pi too, but Pi-hole is more established and has a larger community.
• Media server (Plex/Jellyfin): A Pi 4 can transcode one 1080p stream, but it’s not ideal for a serious media library. It also requires large storage, which means more power and heat.
• Game server (Minecraft): A Pi 4 can run a small Minecraft server for 2–4 players, but it’s CPU-intensive and will wear out the SD card faster.

For a “set and forget� project, Pi-hole is the winner because it’s lightweight, useful, and has a very low failure rate.

Costs and Power Consumption

The Raspberry Pi itself costs $35–$80 depending on model. Add a microSD card ($10–$20), a power supply ($10), and a case ($5–$15). Total initial cost: $50–$100. Running 24/7 at 3W costs about $3–$5 per year at typical US electricity rates. Compare that to a small NUC or an old PC that might draw 20–50W idle, costing $20–$60 per year. A Pi pays for itself in a year.

If you want to run more services, consider a Pi 4 with 4GB RAM and an SSD. That adds maybe $30–$50 but still keeps total power under 5W.

Safety and Longevity Tips

• Use a good power supply and a short, thick USB cable to avoid voltage drops.
• Keep the Pi in a well-ventilated case. A Pi 4 can run hot, but under Pi-hole load it stays cool. If you add more services, add a small fan or heatsink.
• Back up your SD card image periodically (use dd or a tool like Balena Etcher’s clone feature). You can also use Pi-hole’s built-in Teleporter to back up settings.
• Enable SSH with key-based auth and disable password login if you expose it to the internet (though you shouldn’t expose Pi-hole directly).
• Set up automatic updates: pihole -up updates Pi-hole, and you can add a cron job for weekly updates of the blocklists.

Alternatives and Extensions

Once Pi-hole is running, you can extend it:

• Pair it with Unbound to run your own recursive DNS server, which improves privacy and avoids third-party DNS.
• Install WireGuard on the same Pi to use Pi-hole when you’re away from home.
• Add Uptime Kuma to monitor your Pi and other services, sending alerts if something goes down.
• Use Gravity Sync to keep two Pi-holes in sync if you have a second Pi or a server.

If you don’t want to run your own hardware, you can use a free tier cloud VM, but that costs more in the long run and defeats the purpose of a homelab.

Frequently Asked Questions

Will Pi-hole slow down my internet?

No. DNS resolution adds a few milliseconds, and Pi-hole on a Pi 4 can handle thousands of queries per second. You won’t notice any difference in browsing speed; in fact, pages may load faster because ad requests are blocked.

Do I need a static IP for the Pi?

Yes, you should assign a static IP to the Pi (either via DHCP reservation on your router or by editing /etc/dhcpcd.conf). If the IP changes, devices won’t be able to reach the DNS server and you’ll lose internet on all devices.

Can I run Pi-hole on a Raspberry Pi Zero?

Yes, a Pi Zero 2 W works, but it’s slower and has less RAM. It’s fine for a small home network, but if you also want to run a VPN or other services, get a Pi 3 or 4.

Will Pi-hole break my Wi-Fi or IoT devices?

Usually not, but some IoT devices (like smart bulbs) may rely on cloud services that are blocked. If that happens, you can whitelist the specific domain from the Pi-hole dashboard. Most devices work fine.

How do I update Pi-hole?

Run pihole -up in the terminal. This updates the core software and blocklists. You can also set up a cron job to run it weekly, but be aware that updates may occasionally require a reboot.

Can I use Pi-hole with a VPN?

Yes, you can install WireGuard on the same Pi and configure it to use Pi-hole as the DNS for VPN clients. That way you get ad blocking even when you’re away from home. This is a common and well-documented setup.

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in t | Time (hours) | h | 24 | 0 | 8760
in w | Power draw (watts) | W | 3 | 0 | 20
out energy | Energy per day | kWh | (t * w) / 1000 | 3
out cost | Daily cost at $0.15/kWh | USD | ((t * w) / 1000) * 0.15 | 2