diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index 2963acd958..da7b9b5bb5 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -527,9 +527,9 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog, bool a
     {
         if (anonymousMode) {
             if(spark::IsSparkAllowed()) {
-                // 924 is constant part, mainly Schnorr and Range proofs, 2535 is for each grootle proof/aux data
-                // 213 for each private output, 144 other parts of tx,
-                nBytes = 924 + 2535 * (vOutputs.size()) + 213 * CoinControlDialog::payAmounts.size() + 144;
+                // 924 is constant part, mainly Schnorr and Range proofs, 1803 is for each grootle proof/aux data
+                // 213 for each private output,
+                nBytes = 924 + 1803 * (vOutputs.size()) + 322 * CoinControlDialog::payAmounts.size();
             } else {
                 // 1054 is constant part, mainly Schnorr and Range proofs, 2560 is for each sigma/aux data
                 // 83 assuming 1 jmint, 34 is the size of each normal vout,  10 is the size of empty transaction, 52 other constant parts
diff --git a/src/spark/sparkwallet.cpp b/src/spark/sparkwallet.cpp
index 79c973703b..23bd19ab49 100644
--- a/src/spark/sparkwallet.cpp
+++ b/src/spark/sparkwallet.cpp
@@ -1697,9 +1697,9 @@ std::pair<CAmount, std::vector<CSparkMintMeta>> CSparkWallet::SelectSparkCoins(
             throw std::invalid_argument(_("Unable to select cons for spend"));
         }
 
-        // 924 is constant part, mainly Schnorr and Range proofs, 2535 is for each grootle proof/aux data
-        // 213 for each private output, 144 other parts of tx,
-        size = 924 + 2535 * (spendCoins.size()) + 213 * mintNum + 144; //TODO (levon) take in account also utxoNum
+        // 1803 is for first grootle proof/aux data
+        // 213 for each private output, 34 for each utxo,924 constant parts of tx parts of tx,
+        size = 924 + 1803*(spendCoins.size()) + 322*(mintNum+1) + 34*utxoNum;
         CAmount feeNeeded = CWallet::GetMinimumFee(size, nTxConfirmTarget, mempool);
 
         if (fee >= feeNeeded) {