diff --git a/src/db.rs b/src/db.rs
--- a/src/db.rs
+++ b/src/db.rs
@@ -283,33 +283,47 @@
     pool
 }
 
-pub async fn connect_backfill_pool(url: &str, backend: DatabaseBackend) -> AnyPool {
-    let max_connections: u32 = std::env::var("BACKFILL_DATABASE_MAX_CONNECTIONS")
+pub fn backfill_pool_ceiling(backend: DatabaseBackend) -> u32 {
+    match backend {
+        DatabaseBackend::Sqlite => 64,
+        DatabaseBackend::Postgres => 256,
+    }
+}
+
+pub fn needed_backfill_connections(pds: u32, dids_per_pds: u32, resolution: u32) -> u32 {
+    (pds * dids_per_pds) + resolution + 4
+}
+
+pub fn compute_backfill_pool_size(
+    backend: DatabaseBackend,
+    pds: u32,
+    dids_per_pds: u32,
+    resolution: u32,
+) -> u32 {
+    std::env::var("BACKFILL_DATABASE_MAX_CONNECTIONS")
         .ok()
         .and_then(|v| v.parse::<u32>().ok())
         .unwrap_or_else(|| {
-            let pds: u32 = std::env::var("BACKFILL_CONCURRENT_PDS")
-                .ok()
-                .and_then(|v| v.parse().ok())
-                .unwrap_or(10);
-            let dids: u32 = std::env::var("BACKFILL_CONCURRENT_DIDS_PER_PDS")
-                .ok()
-                .and_then(|v| v.parse().ok())
-                .unwrap_or(3);
-            let resolution: u32 = std::env::var("BACKFILL_CONCURRENT_RESOLUTION")
-                .ok()
-                .and_then(|v| v.parse().ok())
-                .unwrap_or(100);
-            // Each concurrent worker may need a connection: PDS×DIDs for fetching +
-            // resolution concurrency + a few for bookkeeping queries.
-            let needed = (pds * dids) + resolution + 4;
-            let ceiling = match backend {
-                DatabaseBackend::Sqlite => 64,
-                DatabaseBackend::Postgres => 256,
-            };
-            needed.min(ceiling)
+            needed_backfill_connections(pds, dids_per_pds, resolution)
+                .min(backfill_pool_ceiling(backend))
         })
-        .max(1);
+        .max(1)
+}
+
+pub async fn connect_backfill_pool(url: &str, backend: DatabaseBackend) -> AnyPool {
+    let pds: u32 = std::env::var("BACKFILL_CONCURRENT_PDS")
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(10);
+    let dids: u32 = std::env::var("BACKFILL_CONCURRENT_DIDS_PER_PDS")
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(3);
+    let resolution: u32 = std::env::var("BACKFILL_CONCURRENT_RESOLUTION")
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(100);
+    let max_connections = compute_backfill_pool_size(backend, pds, dids, resolution);
 
     tracing::info!(max_connections, "backfill pool sized");
 
diff --git a/src/admin/settings.rs b/src/admin/settings.rs
--- a/src/admin/settings.rs
+++ b/src/admin/settings.rs
@@ -204,11 +204,11 @@
     let main_pool_size = state.db.options().get_max_connections() as i64;
     let backfill_pool_size = state.backfill_db.options().get_max_connections() as i64;
 
-    let pds: i64 = get_setting(&state.db, "backfill_concurrent_pds", state.db_backend)
+    let pds: u32 = get_setting(&state.db, "backfill_concurrent_pds", state.db_backend)
         .await
         .and_then(|v| v.parse().ok())
         .unwrap_or(10);
-    let dids: i64 = get_setting(
+    let dids: u32 = get_setting(
         &state.db,
         "backfill_concurrent_dids_per_pds",
         state.db_backend,
@@ -216,7 +216,7 @@
     .await
     .and_then(|v| v.parse().ok())
     .unwrap_or(3);
-    let resolution: i64 = get_setting(
+    let resolution: u32 = get_setting(
         &state.db,
         "backfill_concurrent_resolution",
         state.db_backend,
@@ -224,8 +224,9 @@
     .await
     .and_then(|v| v.parse().ok())
     .unwrap_or(100);
-    let needed_backfill_pool = (pds * dids) + resolution + 4;
-    let restart_recommended = needed_backfill_pool > backfill_pool_size;
+    let would_be_pool_size =
+        crate::db::compute_backfill_pool_size(state.db_backend, pds, dids, resolution);
+    let restart_recommended = would_be_pool_size as i64 > backfill_pool_size;
 
     Ok(Json(serde_json::json!({
         "backend": match state.db_backend {