diff --git a/scripts/build_kraken2_db.sh b/scripts/build_kraken2_db.sh
index a5dfa1e..5fb57ad 100755
--- a/scripts/build_kraken2_db.sh
+++ b/scripts/build_kraken2_db.sh
@@ -64,14 +64,14 @@ then
   KRAKEN2XFLAG="-X"
 fi
 
-echo "Creating sequence ID to taxonomy ID map (step 1)..."
-if [ -d "library/added" ]; then
-  find library/added/ -name 'prelim_map_*.txt' | xargs cat > library/added/prelim_map.txt
-fi
 seqid2taxid_map_file=seqid2taxid.map
 if [ -e "$seqid2taxid_map_file" ]; then
-  echo "Sequence ID to taxonomy ID map already present, skipping map creation."
+  echo "Sequence ID to taxonomy ID map already present, skipping map creation (step 1)."
 else
+  echo "Creating sequence ID to taxonomy ID map (step 1)..."
+  if [ -d "library/added" ]; then
+    find library/added/ -name 'prelim_map_*.txt' | xargs cat > library/added/prelim_map.txt
+  fi
   step_time=$(get_current_time)
   find library/ -maxdepth 2 -name prelim_map.txt | xargs cat > taxonomy/prelim_map.txt
   if [ ! -s "taxonomy/prelim_map.txt" ]; then
@@ -95,28 +95,35 @@ else
   echo "Sequence ID to taxonomy ID map complete. [$(report_time_elapsed $step_time)]"
 fi
 
-echo "Estimating required capacity (step 2)..."
-
-step_time=$(get_current_time)
-estimate=$(list_sequence_files | xargs -0 cat | estimate_capacity -k $KRAKEN2_KMER_LEN -l $KRAKEN2_MINIMIZER_LEN -S $KRAKEN2_SEED_TEMPLATE -p $KRAKEN2_THREAD_CT $KRAKEN2XFLAG )
-# Slight upward adjustment of distinct minimizer estimate to protect
-# against crash w/ small reference sets
-estimate=$(( estimate + 8192 ))
-required_capacity=$(perl -le 'print int(shift() / shift())' $estimate $KRAKEN2_LOAD_FACTOR);
-
-echo "Estimated hash table requirement: $(( required_capacity * 4 )) bytes"
-
+required_capacity_file="required_capacity.txt"
 max_db_flag=""
-if [ -n "$KRAKEN2_MAX_DB_SIZE" ]
-then
-  if (( KRAKEN2_MAX_DB_SIZE < (required_capacity * 4) ))
+if [ -e "$required_capacity_file" ]; then
+  echo "Required capacity has already been estimated, skipping estimation (step 2)."
+  required_capacity=$( < $required_capacity_file )
+else
+  echo "Estimating required capacity (step 2)..."
+
+  step_time=$(get_current_time)
+  estimate=$(list_sequence_files | xargs -0 cat | estimate_capacity -k $KRAKEN2_KMER_LEN -l $KRAKEN2_MINIMIZER_LEN -S $KRAKEN2_SEED_TEMPLATE -p $KRAKEN2_THREAD_CT $KRAKEN2XFLAG )
+  # Slight upward adjustment of distinct minimizer estimate to protect
+  # against crash w/ small reference sets
+  estimate=$(( estimate + 8192 ))
+  required_capacity=$(perl -le 'print int(shift() / shift())' $estimate $KRAKEN2_LOAD_FACTOR);
+  echo $required_capacity > $required_capacity_file
+
+  if [ -n "$KRAKEN2_MAX_DB_SIZE" ]
   then
-    max_db_flag="-M $(perl -le 'print int(shift() / 4)' $KRAKEN2_MAX_DB_SIZE)"
-    echo "Specifying lower maximum hash table size of $KRAKEN2_MAX_DB_SIZE bytes"
+    if (( KRAKEN2_MAX_DB_SIZE < (required_capacity * 4) ))
+    then
+      max_db_flag="-M $(perl -le 'print int(shift() / 4)' $KRAKEN2_MAX_DB_SIZE)"
+      echo "Specifying lower maximum hash table size of $KRAKEN2_MAX_DB_SIZE bytes"
+    fi
   fi
+
+  echo "Capacity estimation complete. [$(report_time_elapsed $step_time)]"
 fi
+echo "Estimated hash table requirement: $(( required_capacity * 4 )) bytes"
 
-echo "Capacity estimation complete. [$(report_time_elapsed $step_time)]"
 
 echo "Building database files (step 3)..."