diff --git a/src/main.h b/src/main.h
index eb045ae0e..8f6b13749 100644
--- a/src/main.h
+++ b/src/main.h
@@ -872,8 +872,6 @@ extern CBlockTreeDB *pblocktree;
  */
 int GetSpendHeight(const CCoinsViewCache& inputs);
 
-namespace Consensus {
-bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, const Consensus::Params& consensusParams);
-}
+uint64_t CalculateCurrentUsage();
 
 #endif // BITCOIN_MAIN_H
diff --git a/src/rpcblockchain.cpp b/src/rpcblockchain.cpp
index 8d7d85ccd..e57d2f952 100644
--- a/src/rpcblockchain.cpp
+++ b/src/rpcblockchain.cpp
@@ -889,6 +889,7 @@ UniValue getblockchaininfo(const UniValue& params, bool fHelp)
             "  \"difficulty\": xxxxxx,     (numeric) the current difficulty\n"
             "  \"verificationprogress\": xxxx, (numeric) estimate of verification progress [0..1]\n"
             "  \"chainwork\": \"xxxx\"     (string) total amount of work in active chain, in hexadecimal\n"
+            "  \"size_on_disk\": xxxxxx,       (numeric) the estimated size of the block and undo files on disk\n"
             "  \"commitments\": xxxxxx,    (numeric) the current number of note commitments in the commitment tree\n"
             "  \"softforks\": [            (array) status of softforks in progress\n"
             "     {\n"
@@ -920,6 +921,7 @@ UniValue getblockchaininfo(const UniValue& params, bool fHelp)
     obj.push_back(Pair("verificationprogress",  Checkpoints::GuessVerificationProgress(Params().Checkpoints(), chainActive.Tip())));
     obj.push_back(Pair("chainwork",             chainActive.Tip()->nChainWork.GetHex()));
     obj.push_back(Pair("pruned",                fPruneMode));
+    obj.push_back(Pair("size_on_disk",          CalculateCurrentUsage()));
 
     ZCIncrementalMerkleTree tree;
     pcoinsTip->GetAnchorAt(pcoinsTip->GetBestAnchor(), tree);