diff --git a/src/validation.cpp b/src/validation.cpp
index 3f774fd0a1e63..191d80ef06f21 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -88,6 +88,8 @@ using node::CBlockIndexHeightOnlyComparator;
 using node::CBlockIndexWorkComparator;
 using node::SnapshotMetadata;
 
+/** Size threshold for warning about slow UTXO set flush to disk. */
+static constexpr size_t WARN_FLUSH_COINS_SIZE = 1 << 30; // 1 GiB
 /** Time to wait between writing blocks/block index to disk. */
 static constexpr std::chrono::hours DATABASE_WRITE_INTERVAL{1};
 /** Time to wait between flushing chainstate to disk. */
@@ -2929,8 +2931,9 @@ bool Chainstate::FlushStateToDisk(
         }
         // Flush best chain related state. This can only be done if the blocks / block index write was also done.
         if (fDoFullFlush && !CoinsTip().GetBestBlock().IsNull()) {
-            LOG_TIME_MILLIS_WITH_CATEGORY(strprintf("write coins cache to disk (%d coins, %.2fkB)",
-                coins_count, coins_mem_usage / 1000), BCLog::BENCH);
+            if (coins_mem_usage >= WARN_FLUSH_COINS_SIZE) LogWarning("Flushing large (%d GiB) UTXO set to disk, it may take several minutes", coins_mem_usage >> 30);
+            LOG_TIME_MILLIS_WITH_CATEGORY(strprintf("write coins cache to disk (%d coins, %.2fKiB)",
+                coins_count, coins_mem_usage >> 10), BCLog::BENCH);
 
             // Typical Coin structures on disk are around 48 bytes in size.
             // Pushing a new one to the database can cause it to be written