diff --git a/docs/source/reference/monitoring.md b/docs/source/reference/monitoring.md
index a1a01635..a3649c82 100644
--- a/docs/source/reference/monitoring.md
+++ b/docs/source/reference/monitoring.md
@@ -18,3 +18,17 @@ tool like [Grafana](https://grafana.com).
 
 /reference/metrics
 ```
+
+## Customizing the metrics prefix
+
+JupyterHub metrics all have a `jupyterhub_` prefix.
+As of JupyterHub 5.0, this can be overridden with `$JUPYTERHUB_METRICS_PREFIX` environment variable
+in the Hub's environment.
+
+For example,
+
+```bash
+export JUPYTERHUB_METRICS_PREFIX=jupyterhub_prod
+```
+
+would result in the metric `jupyterhub_prod_active_users`, etc.
diff --git a/jupyterhub/metrics.py b/jupyterhub/metrics.py
index 23b37d55..c3bfd42d 100644
--- a/jupyterhub/metrics.py
+++ b/jupyterhub/metrics.py
@@ -6,6 +6,8 @@ conventions for metrics & labels. We generally prefer naming them
 `<noun>_<verb>_<type_suffix>`. So a histogram that's tracking
 the duration (in seconds) of servers spawning would be called
 server_spawn_duration_seconds.
+A namespace prefix is always added, so this metric is accessed as
+`jupyterhub_server_spawn_duration_seconds` by default.
 
 We also create an Enum for each 'status' type label in every metric
 we collect. This is to make sure that the metrics exist regardless