diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 154107c0d..a6f92ea20 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -331,7 +331,7 @@ UniValue getdifficulty(const JSONRPCRequest& request)
 
 std::string EntryDescriptionString()
 {
-    return "    \"size\" : n,             (numeric) transaction size in bytes\n"
+    return "    \"size\" : n,             (numeric) virtual transaction size as defined in BIP 141. This is different from actual serialized size for witness transactions as witness data is discounted.\n"
            "    \"fee\" : n,              (numeric) transaction fee in " + CURRENCY_UNIT + "\n"
            "    \"modifiedfee\" : n,      (numeric) transaction fee with fee deltas used for mining priority\n"
            "    \"time\" : n,             (numeric) local time transaction entered pool in seconds since 1 Jan 1970 GMT\n"
@@ -339,10 +339,10 @@ std::string EntryDescriptionString()
            "    \"startingpriority\" : n, (numeric) priority when transaction entered pool\n"
            "    \"currentpriority\" : n,  (numeric) transaction priority now\n"
            "    \"descendantcount\" : n,  (numeric) number of in-mempool descendant transactions (including this one)\n"
-           "    \"descendantsize\" : n,   (numeric) size of in-mempool descendants (including this one)\n"
+           "    \"descendantsize\" : n,   (numeric) virtual transaction size of in-mempool descendants (including this one)\n"
            "    \"descendantfees\" : n,   (numeric) modified fees (see above) of in-mempool descendants (including this one)\n"
            "    \"ancestorcount\" : n,    (numeric) number of in-mempool ancestor transactions (including this one)\n"
-           "    \"ancestorsize\" : n,     (numeric) size of in-mempool ancestors (including this one)\n"
+           "    \"ancestorsize\" : n,     (numeric) virtual transaction size of in-mempool ancestors (including this one)\n"
            "    \"ancestorfees\" : n,     (numeric) modified fees (see above) of in-mempool ancestors (including this one)\n"
            "    \"depends\" : [           (array) unconfirmed transactions used as inputs for this transaction\n"
            "        \"transactionid\",    (string) parent transaction id\n"
@@ -703,7 +703,7 @@ UniValue getblock(const JSONRPCRequest& request)
             "  \"confirmations\" : n,   (numeric) The number of confirmations, or -1 if the block is not on the main chain\n"
             "  \"size\" : n,            (numeric) The block size\n"
             "  \"strippedsize\" : n,    (numeric) The block size excluding witness data\n"
-            "  \"weight\" : n           (numeric) The block weight (BIP 141)\n"
+            "  \"weight\" : n           (numeric) The block weight as defined in BIP 141\n"
             "  \"height\" : n,          (numeric) The block height or index\n"
             "  \"version\" : n,         (numeric) The block version\n"
             "  \"versionHex\" : \"00000000\", (string) The block version formatted in hexadecimal\n"
@@ -1240,7 +1240,7 @@ UniValue getmempoolinfo(const JSONRPCRequest& request)
             "\nResult:\n"
             "{\n"
             "  \"size\": xxxxx,               (numeric) Current tx count\n"
-            "  \"bytes\": xxxxx,              (numeric) Sum of all tx sizes\n"
+            "  \"bytes\": xxxxx,              (numeric) Sum of all virtual transaction sizes as defined in BIP 141. Differs from actual serialized size because witness data is discounted\n"
             "  \"usage\": xxxxx,              (numeric) Total memory usage for the mempool\n"
             "  \"maxmempool\": xxxxx,         (numeric) Maximum memory usage for the mempool\n"
             "  \"mempoolminfee\": xxxxx       (numeric) Minimum fee for tx to be accepted\n"
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 6b0e52a30..724594c8d 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -775,7 +775,8 @@ UniValue estimatefee(const JSONRPCRequest& request)
         throw runtime_error(
             "estimatefee nblocks\n"
             "\nEstimates the approximate fee per kilobyte needed for a transaction to begin\n"
-            "confirmation within nblocks blocks.\n"
+            "confirmation within nblocks blocks. Uses virtual transaction size of transaction\n"
+            "as defined in BIP 141 (witness data is discounted).\n"
             "\nArguments:\n"
             "1. nblocks     (numeric)\n"
             "\nResult:\n"
@@ -835,7 +836,8 @@ UniValue estimatesmartfee(const JSONRPCRequest& request)
             "\nWARNING: This interface is unstable and may disappear or change!\n"
             "\nEstimates the approximate fee per kilobyte needed for a transaction to begin\n"
             "confirmation within nblocks blocks if possible and return the number of blocks\n"
-            "for which the estimate is valid.\n"
+            "for which the estimate is valid. Uses virtual transaction size as defined\n"
+            "in BIP 141 (witness data is discounted).\n"
             "\nArguments:\n"
             "1. nblocks     (numeric)\n"
             "\nResult:\n"
diff --git a/src/txmempool.h b/src/txmempool.h
index 29b59363a..ced74aa47 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -421,7 +421,7 @@ private:
     unsigned int nTransactionsUpdated;
     CBlockPolicyEstimator* minerPolicyEstimator;
 
-    uint64_t totalTxSize;      //!< sum of all mempool tx' byte sizes
+    uint64_t totalTxSize;      //!< sum of all mempool tx's virtual sizes. Differs from serialized tx size since witness data is discounted. Defined in BIP 141.
     uint64_t cachedInnerUsage; //!< sum of dynamic memory usage of all the map elements (NOT the maps themselves)
 
     CFeeRate minReasonableRelayFee;