diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index 477cee1c04..c19420beb5 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -490,7 +490,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
         else nBytesInputs += 148;
     }
 
-    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET);
+    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET, coinControl->signalRbf);
 
     // calculation
     if (nQuantity > 0)
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index d9439fe248..27634eb179 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -166,6 +166,8 @@ void SendCoinsDialog::setModel(WalletModel *_model)
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateFeeSectionControls()));
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(updateGlobalFeeVariables()));
         connect(ui->checkBoxMinimumFee, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
+        connect(ui->optInRBF, SIGNAL(stateChanged(int)), this, SLOT(updateSmartFeeLabel()));
+        connect(ui->optInRBF, SIGNAL(stateChanged(int)), this, SLOT(coinControlUpdateLabels()));
         ui->customFee->setSingleStep(CWallet::GetRequiredFee(1000));
         updateFeeSectionControls();
         updateMinFeeLabel();
@@ -652,7 +654,7 @@ void SendCoinsDialog::updateSmartFeeLabel()
 
     int nBlocksToConfirm = ui->sliderSmartFee->maximum() - ui->sliderSmartFee->value() + 2;
     FeeCalculation feeCalc;
-    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET);
+    bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET, ui->optInRBF->isChecked());
     CFeeRate feeRate = ::feeEstimator.estimateSmartFee(nBlocksToConfirm, &feeCalc, ::mempool, conservative_estimate);
     if (feeRate <= CFeeRate(0)) // not enough data => minfee
     {
@@ -828,6 +830,7 @@ void SendCoinsDialog::coinControlUpdateLabels()
     } else {
         CoinControlDialog::coinControl->nConfirmTarget = model->getDefaultConfirmTarget();
     }
+    CoinControlDialog::coinControl->signalRbf = ui->optInRBF->isChecked();
 
     for(int i = 0; i < ui->entries->count(); ++i)
     {
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index a36f6798f0..a25530d8bd 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -165,7 +165,7 @@ CFeeBumper::CFeeBumper(const CWallet *pWallet, const uint256 txidIn, int newConf
         nNewFee = totalFee;
         nNewFeeRate = CFeeRate(totalFee, maxNewTxSize);
     } else {
-        bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET);
+        bool conservative_estimate = CalculateEstimateType(FeeEstimateMode::UNSET, newTxReplaceable);
         nNewFee = CWallet::GetMinimumFee(maxNewTxSize, newConfirmTarget, mempool, ::feeEstimator, nullptr /* FeeCalculation */, ignoreGlobalPayTxFee, conservative_estimate);
         nNewFeeRate = CFeeRate(nNewFee, maxNewTxSize);
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index a43b5398e0..9a5f6b2791 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2725,7 +2725,7 @@ bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CWalletT
                     currentConfirmationTarget = coinControl->nConfirmTarget;
 
                 // Allow to override the default fee estimate mode over the CoinControl instance
-                bool conservative_estimate = CalculateEstimateType(coinControl ? coinControl->m_fee_mode : FeeEstimateMode::UNSET);
+                bool conservative_estimate = CalculateEstimateType(coinControl ? coinControl->m_fee_mode : FeeEstimateMode::UNSET, rbf);
 
                 CAmount nFeeNeeded = GetMinimumFee(nBytes, currentConfirmationTarget, ::mempool, ::feeEstimator, &feeCalc, false /* ignoreGlobalPayTxFee */, conservative_estimate);
                 if (coinControl && coinControl->fOverrideFeeRate)
@@ -4158,9 +4158,10 @@ bool CMerkleTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState&
     return ::AcceptToMemoryPool(mempool, state, tx, true, NULL, NULL, false, nAbsurdFee);
 }
 
-bool CalculateEstimateType(FeeEstimateMode mode) {
+bool CalculateEstimateType(FeeEstimateMode mode, bool opt_in_rbf) {
     switch (mode) {
     case FeeEstimateMode::UNSET:
+        return !opt_in_rbf; // Allow for lower fees if RBF is an option
     case FeeEstimateMode::CONSERVATIVE:
         return true;
     case FeeEstimateMode::ECONOMICAL:
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 813bf530ac..e3715cdf37 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1213,6 +1213,6 @@ bool CWallet::DummySignTx(CMutableTransaction &txNew, const ContainerType &coins
     return true;
 }
 
-bool CalculateEstimateType(FeeEstimateMode mode);
+bool CalculateEstimateType(FeeEstimateMode mode, bool opt_in_rbf);
 
 #endif // BITCOIN_WALLET_WALLET_H