diff --git a/README.md b/README.md
index 5cedc41..4029716 100644
--- a/README.md
+++ b/README.md
@@ -81,9 +81,46 @@ ADMIN_PASSWORD=... DB_PATH=/var/lib/wutzcalc/wutz.db node server/dist/index.js
 Single Node process serves the API, both client entries (`/` tablet,
 `/admin` backoffice), and writes to one SQLite file.
 
+## Run as a systemd service
+
+Template files live in [`deploy/`](deploy/): a unit ([`wutzcalc.service`](deploy/wutzcalc.service))
+and an environment file ([`wutzcalc.env.example`](deploy/wutzcalc.env.example)).
+They assume the built app lives in `/opt/wutzcalc` and the database in
+`/var/lib/wutzcalc` — adjust paths in the unit if yours differ.
+
+```sh
+# 1. Dedicated system user (no login, no home)
+sudo useradd --system --no-create-home --shell /usr/sbin/nologin wutzcalc
+
+# 2. Install the built app (run `pnpm install && pnpm build` first)
+sudo mkdir -p /opt/wutzcalc
+sudo cp -a . /opt/wutzcalc            # or rsync/checkout into place
+sudo chown -R root:root /opt/wutzcalc # app dir stays read-only to the service
+
+# 3. Config + secrets (chmod 600 — holds ADMIN_PASSWORD)
+sudo mkdir -p /etc/wutzcalc
+sudo install -m 600 deploy/wutzcalc.env.example /etc/wutzcalc/wutzcalc.env
+sudoedit /etc/wutzcalc/wutzcalc.env    # set ADMIN_PASSWORD
+
+# 4. Install and start the unit
+sudo cp deploy/wutzcalc.service /etc/systemd/system/
+sudo systemctl daemon-reload
+sudo systemctl enable --now wutzcalc
+
+# Logs / status
+systemctl status wutzcalc
+journalctl -u wutzcalc -f
+```
+
+Confirm `ExecStart` matches your Node path (`command -v node`) — it defaults to
+`/usr/bin/node`. The unit creates `/var/lib/wutzcalc` via `StateDirectory`, so
+the service user owns the database directory automatically.
+
 ## Env vars
 
 - `PORT` (default `3000`)
 - `HOST` (default `0.0.0.0`)
 - `DB_PATH` (default `./wutz.db`)
 - `ADMIN_PASSWORD` (**required** for backoffice login)
+- `WUTZ_TZ` (default `Europe/Berlin`) — timezone for stats display and grouping
+- `WUTZ_DAY_CUTOFF_HOUR` (default `5`) — sales before this local hour count toward the previous business day
diff --git a/deploy/wutzcalc.env.example b/deploy/wutzcalc.env.example
new file mode 100644
index 0000000..6eed85d
--- /dev/null
+++ b/deploy/wutzcalc.env.example
@@ -0,0 +1,18 @@
+# Copy to /etc/wutzcalc/wutzcalc.env and edit.
+# Keep it readable only by root / the service user — it holds the admin password:
+#   sudo install -m 600 -o root -g root deploy/wutzcalc.env.example /etc/wutzcalc/wutzcalc.env
+
+# Required: backoffice login password.
+ADMIN_PASSWORD=changeme
+
+# SQLite database file. With StateDirectory=wutzcalc this dir is created for you.
+DB_PATH=/var/lib/wutzcalc/wutz.db
+
+# Network bind (defaults: 0.0.0.0:3000).
+PORT=3000
+HOST=0.0.0.0
+
+# Sales-day handling (defaults shown). Hours before the cutoff count toward the
+# previous business day, so a 03:00 sale lands on the night before.
+#WUTZ_TZ=Europe/Berlin
+#WUTZ_DAY_CUTOFF_HOUR=5
diff --git a/deploy/wutzcalc.service b/deploy/wutzcalc.service
new file mode 100644
index 0000000..75bde31
--- /dev/null
+++ b/deploy/wutzcalc.service
@@ -0,0 +1,38 @@
+[Unit]
+Description=wutzcalc — festival drink-sale tracker
+Documentation=https://git.berlin.ccc.de/vinzenz/wutzcalc
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=wutzcalc
+Group=wutzcalc
+
+# Where `pnpm build` was run — adjust to your install location.
+WorkingDirectory=/opt/wutzcalc
+# `which node` may differ (e.g. /usr/local/bin/node or an nvm path).
+ExecStart=/usr/bin/node server/dist/index.js
+
+# Secrets and config live here, not in the unit. See wutzcalc.env.example.
+EnvironmentFile=/etc/wutzcalc/wutzcalc.env
+
+Restart=on-failure
+RestartSec=5
+
+# Creates/owns /var/lib/wutzcalc — point DB_PATH there.
+StateDirectory=wutzcalc
+
+# Hardening
+NoNewPrivileges=true
+ProtectSystem=strict
+ProtectHome=true
+PrivateTmp=true
+PrivateDevices=true
+ProtectKernelTunables=true
+ProtectControlGroups=true
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+ReadWritePaths=/var/lib/wutzcalc
+
+[Install]
+WantedBy=multi-user.target