diff --git a/src/blockchain_db/berkeleydb/db_bdb.cpp b/src/blockchain_db/berkeleydb/db_bdb.cpp
index 221c0cf2..efe8528c 100644
--- a/src/blockchain_db/berkeleydb/db_bdb.cpp
+++ b/src/blockchain_db/berkeleydb/db_bdb.cpp
@@ -1595,7 +1595,7 @@ bool BlockchainBDB::has_key_image(const crypto::key_image& img) const
 // Ostensibly BerkeleyDB has batch transaction support built-in,
 // so the following few functions will be NOP.
 
-void BlockchainBDB::batch_start()
+void BlockchainBDB::batch_start(uint64_t batch_num_blocks)
 {
   LOG_PRINT_L3("BlockchainBDB::" << __func__);
 }
diff --git a/src/blockchain_db/berkeleydb/db_bdb.h b/src/blockchain_db/berkeleydb/db_bdb.h
index 83588b03..da57cabb 100644
--- a/src/blockchain_db/berkeleydb/db_bdb.h
+++ b/src/blockchain_db/berkeleydb/db_bdb.h
@@ -191,7 +191,7 @@ public:
                             );
 
   virtual void set_batch_transactions(bool batch_transactions);
-  virtual void batch_start();
+  virtual void batch_start(uint64_t batch_num_blocks=0);
   virtual void batch_commit();
   virtual void batch_stop();
   virtual void batch_abort();
diff --git a/src/blockchain_db/blockchain_db.h b/src/blockchain_db/blockchain_db.h
index 46c86012..c4ca328f 100644
--- a/src/blockchain_db/blockchain_db.h
+++ b/src/blockchain_db/blockchain_db.h
@@ -357,7 +357,7 @@ public:
   // release db lock
   virtual void unlock() = 0;
 
-  virtual void batch_start() = 0;
+  virtual void batch_start(uint64_t batch_num_blocks=0) = 0;
   virtual void batch_stop() = 0;
   virtual void set_batch_transactions(bool) = 0;
 
diff --git a/src/blockchain_db/lmdb/db_lmdb.cpp b/src/blockchain_db/lmdb/db_lmdb.cpp
index 0ed04495..0d0b8ba8 100644
--- a/src/blockchain_db/lmdb/db_lmdb.cpp
+++ b/src/blockchain_db/lmdb/db_lmdb.cpp
@@ -233,7 +233,7 @@ void mdb_txn_safe::allow_new_txns()
 
 
 
-void BlockchainLMDB::do_resize()
+void BlockchainLMDB::do_resize(uint64_t increase_size)
 {
   MDB_envinfo mei;
 
@@ -244,6 +244,11 @@ void BlockchainLMDB::do_resize()
   mdb_env_stat(m_env, &mst);
 
   uint64_t new_mapsize = (double)mei.me_mapsize * RESIZE_FACTOR;
+  // If given, use increase_size intead of above way of resizing.
+  // This is currently used for increasing by an estimated size at start of new
+  // batch txn.
+  if (increase_size > 0)
+    new_mapsize = mei.me_mapsize + increase_size;
 
   new_mapsize += (new_mapsize % mst.ms_psize);
 
@@ -272,7 +277,8 @@ void BlockchainLMDB::do_resize()
   mdb_txn_safe::allow_new_txns();
 }
 
-bool BlockchainLMDB::need_resize() const
+// threshold_size is used for batch transactions
+bool BlockchainLMDB::need_resize(uint64_t threshold_size) const
 {
   MDB_envinfo mei;
 
@@ -282,15 +288,107 @@ bool BlockchainLMDB::need_resize() const
 
   mdb_env_stat(m_env, &mst);
 
+  // size_used doesn't include data yet to be committed, which can be
+  // significant size during batch transactions. For that, we estimate the size
+  // needed at the beginning of the batch transaction and pass in the
+  // additional size needed.
   uint64_t size_used = mst.ms_psize * mei.me_last_pgno;
 
+  LOG_PRINT_L1("DB map size:     " << mei.me_mapsize);
+  LOG_PRINT_L1("Space used:      " << size_used);
+  LOG_PRINT_L1("Space remaining: " << mei.me_mapsize - size_used);
+  LOG_PRINT_L1("Size threshold:  " << threshold_size);
+  LOG_PRINT_L1("Percent used: " << (double)size_used/mei.me_mapsize << "  Percent threshold: " << RESIZE_PERCENT);
+
+  if (threshold_size > 0)
+  {
+    if (mei.me_mapsize - size_used < threshold_size)
+    {
+      LOG_PRINT_L1("Threshold met (size-based)");
+      return true;
+    }
+    else
+      return false;
+  }
+
   if ((double)size_used / mei.me_mapsize  > RESIZE_PERCENT)
   {
+    LOG_PRINT_L1("Threshold met (percent-based)");
     return true;
   }
   return false;
 }
 
+void BlockchainLMDB::check_and_resize_for_batch(uint64_t batch_num_blocks)
+{
+  LOG_PRINT_L1("[batch] checking DB size");
+  const uint64_t min_increase_size = 128 * (1 << 20);
+  uint64_t threshold_size = 0;
+  uint64_t increase_size = 0;
+  if (batch_num_blocks > 0)
+  {
+    threshold_size = get_estimated_batch_size(batch_num_blocks);
+    LOG_PRINT_L1("calculated batch size: " << threshold_size);
+
+    // The increased DB size could be a multiple of threshold_size, a fixed
+    // size increase (> threshold_size), or other variations.
+    //
+    // Currently we use the greater of threshold size and a minimum size. The
+    // minimum size increase is used to avoid frequent resizes when the batch
+    // size is set to a very small numbers of blocks.
+    increase_size = (threshold_size > min_increase_size) ? threshold_size : min_increase_size;
+    LOG_PRINT_L1("increase size: " << increase_size);
+  }
+
+  // if threshold_size is 0 (i.e. number of blocks for batch not passed in), it
+  // will fall back to the percent-based threshold check instead of the
+  // size-based check
+  if (need_resize(threshold_size))
+  {
+    LOG_PRINT_L0("[batch] DB resize needed");
+    do_resize(increase_size);
+  }
+}
+
+uint64_t BlockchainLMDB::get_estimated_batch_size(uint64_t batch_num_blocks) const
+{
+  uint64_t threshold_size = 0;
+
+  // batch size estimate * batch safety factor = final size estimate
+  // Takes into account "reasonable" block size increases in batch.
+  float batch_safety_factor = 1.7f;
+  // estimate of stored block expanded from raw block, including denormalization and db overhead.
+  // Note that this probably doesn't grow linearly with block size.
+  float db_expand_factor = 4.5f;
+  uint64_t num_prev_blocks = 500;
+  // For resizing purposes, allow for at least 4k average block size.
+  uint64_t min_block_size = 4 * 1024;
+
+  uint64_t block_stop = m_height - 1;
+  uint64_t block_start = 0;
+  if (block_stop >= num_prev_blocks)
+    block_start = block_stop - num_prev_blocks + 1;
+  uint32_t num_blocks_used = 0;
+  uint64_t total_block_size = 0;
+  for (uint64_t block_num = block_start; block_num <= block_stop; ++block_num)
+  {
+    uint32_t block_size = get_block_size(block_num);
+    total_block_size += block_size;
+    // Track number of blocks being totalled here instead of assuming, in case
+    // some blocks were to be skipped for being outliers.
+    ++num_blocks_used;
+  }
+  size_t avg_block_size = total_block_size / num_blocks_used;
+  LOG_PRINT_L1("average block size across recent " << num_blocks_used << " blocks: " << avg_block_size);
+  if (avg_block_size < min_block_size)
+    avg_block_size = min_block_size;
+  LOG_PRINT_L1("estimated average block size for batch: " << avg_block_size);
+
+  threshold_size = avg_block_size * db_expand_factor * batch_num_blocks;
+  threshold_size = threshold_size * batch_safety_factor;
+  return threshold_size;
+}
+
 void BlockchainLMDB::add_block( const block& blk
               , const size_t& block_size
               , const difficulty_type& cumulative_difficulty
@@ -1820,7 +1918,8 @@ bool BlockchainLMDB::has_key_image(const crypto::key_image& img) const
   return false;
 }
 
-void BlockchainLMDB::batch_start()
+// batch_num_blocks: (optional) Used to check if resize needed before batch transaction starts.
+void BlockchainLMDB::batch_start(uint64_t batch_num_blocks)
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
   if (! m_batch_transactions)
@@ -1833,6 +1932,8 @@ void BlockchainLMDB::batch_start()
     throw0(DB_ERROR("batch transaction attempted, but m_write_txn already in use"));
   check_open();
 
+  check_and_resize_for_batch(batch_num_blocks);
+
   m_write_batch_txn = new mdb_txn_safe();
 
   // NOTE: need to make sure it's destroyed properly when done
@@ -1927,7 +2028,8 @@ uint64_t BlockchainLMDB::add_block( const block& blk
 
   if (m_height % 1000 == 0)
   {
-    if (need_resize())
+    // for batch mode, DB resize check is done at start of batch transaction
+    if (! m_batch_active && need_resize())
     {
       LOG_PRINT_L0("LMDB memory map needs resized, doing that now.");
       do_resize();
diff --git a/src/blockchain_db/lmdb/db_lmdb.h b/src/blockchain_db/lmdb/db_lmdb.h
index 6a264681..6f226254 100644
--- a/src/blockchain_db/lmdb/db_lmdb.h
+++ b/src/blockchain_db/lmdb/db_lmdb.h
@@ -191,7 +191,7 @@ public:
                             );
 
   virtual void set_batch_transactions(bool batch_transactions);
-  virtual void batch_start();
+  virtual void batch_start(uint64_t batch_num_blocks=0);
   virtual void batch_commit();
   virtual void batch_stop();
   virtual void batch_abort();
@@ -199,9 +199,11 @@ public:
   virtual void pop_block(block& blk, std::vector<transaction>& txs);
 
 private:
-  void do_resize();
+  void do_resize(uint64_t size_increase=0);
 
-  bool need_resize() const;
+  bool need_resize(uint64_t threshold_size=0) const;
+  void check_and_resize_for_batch(uint64_t batch_num_blocks);
+  uint64_t get_estimated_batch_size(uint64_t batch_num_blocks) const;
 
   virtual void add_block( const block& blk
                 , const size_t& block_size
diff --git a/src/blockchain_utilities/blockchain_converter.cpp b/src/blockchain_utilities/blockchain_converter.cpp
index 855dde64..d18ce878 100644
--- a/src/blockchain_utilities/blockchain_converter.cpp
+++ b/src/blockchain_utilities/blockchain_converter.cpp
@@ -236,7 +236,7 @@ int main(int argc, char* argv[])
   }
 
   if (opt_batch)
-    blockchain->batch_start();
+    blockchain->batch_start(db_batch_size);
   uint64_t i = 0;
   for (i = start_block; i < end_block + 1; ++i)
   {
@@ -277,7 +277,7 @@ int main(int argc, char* argv[])
           std::cout << "\r                   \r";
           std::cout << "[- batch commit at height " << i + 1 << " -]" << ENDL;
           blockchain->batch_stop();
-          blockchain->batch_start();
+          blockchain->batch_start(db_batch_size);
           std::cout << ENDL;
           blockchain->show_stats();
         }
diff --git a/src/blockchain_utilities/blockchain_import.cpp b/src/blockchain_utilities/blockchain_import.cpp
index aeed2b33..924b46d2 100644
--- a/src/blockchain_utilities/blockchain_import.cpp
+++ b/src/blockchain_utilities/blockchain_import.cpp
@@ -254,7 +254,7 @@ int import_from_file(FakeCore& simple_core, std::string& import_file_path, uint6
   }
 
   if (use_batch)
-    simple_core.batch_start();
+    simple_core.batch_start(db_batch_size);
 
   LOG_PRINT_L0("Reading blockchain from bootstrap file...");
   std::cout << ENDL;
@@ -482,7 +482,7 @@ int import_from_file(FakeCore& simple_core, std::string& import_file_path, uint6
             // zero-based height
             std::cout << ENDL << "[- batch commit at height " << h-1 << " -]" << ENDL;
             simple_core.batch_stop();
-            simple_core.batch_start();
+            simple_core.batch_start(db_batch_size);
             std::cout << ENDL;
 #if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
             simple_core.m_storage.get_db().show_stats();
diff --git a/src/blockchain_utilities/bootstrap_file.cpp b/src/blockchain_utilities/bootstrap_file.cpp
index 70f0b1fe..573cb157 100644
--- a/src/blockchain_utilities/bootstrap_file.cpp
+++ b/src/blockchain_utilities/bootstrap_file.cpp
@@ -454,7 +454,7 @@ uint64_t BootstrapFile::count_blocks(const std::string& import_file_path)
     str1.assign(buf1, sizeof(chunk_size));
     if (! ::serialization::parse_binary(str1, chunk_size))
       throw std::runtime_error("Error in deserialization of chunk_size");
-    LOG_PRINT_L1("chunk_size: " << chunk_size);
+    LOG_PRINT_L3("chunk_size: " << chunk_size);
 
     if (chunk_size > BUFFER_SIZE)
     {
diff --git a/src/blockchain_utilities/fake_core.h b/src/blockchain_utilities/fake_core.h
index 79fb5184..5eda504f 100644
--- a/src/blockchain_utilities/fake_core.h
+++ b/src/blockchain_utilities/fake_core.h
@@ -96,9 +96,9 @@ struct fake_core_lmdb
     return m_storage.get_db().add_block(blk, block_size, cumulative_difficulty, coins_generated, txs);
   }
 
-  void batch_start()
+  void batch_start(uint64_t batch_num_blocks = 0)
   {
-    m_storage.get_db().batch_start();
+    m_storage.get_db().batch_start(batch_num_blocks);
   }
 
   void batch_stop()
@@ -150,7 +150,7 @@ struct fake_core_memory
     return 2;
   }
 
-  void batch_start()
+  void batch_start(uint64_t batch_num_blocks = 0)
   {
     LOG_PRINT_L0("WARNING: [batch_start] opt_batch set, but this database doesn't support/need transactions - ignoring");
   }