diff --git a/cw_bitcoin/lib/electrum_fee_estimate.dart b/cw_bitcoin/lib/electrum_fee_estimate.dart
index dc621d739..22e7c130f 100644
--- a/cw_bitcoin/lib/electrum_fee_estimate.dart
+++ b/cw_bitcoin/lib/electrum_fee_estimate.dart
@@ -8,13 +8,13 @@ class ElectrumFeeEstimate extends FeeEstimate {
 
   ElectrumWalletBase _wallet;
 
-  int get({TransactionPriority priority, int amount, int outputsCount}) {
+  int get({TransactionPriority? priority, int? amount, int? outputsCount}) {
     // Electrum doesn't require an async call to obtain the estimated fee.
     // We don't bother caching and just obtain it directly.
     return _wallet.calculateEstimatedFee(priority,amount, outputsCount: outputsCount);
   }
 
-  void update({TransactionPriority priority, int amount, int outputsCount}) {}
+  void update({TransactionPriority? priority, int? amount, int? outputsCount}) {}
 
-  void set({TransactionPriority priority, int outputsCount, int fee}) {}
+  void set({TransactionPriority? priority, int? outputsCount, int? fee}) {}
 }
\ No newline at end of file
diff --git a/cw_bitcoin/lib/electrum_wallet.dart b/cw_bitcoin/lib/electrum_wallet.dart
index fcb6e5269..82c4e205f 100644
--- a/cw_bitcoin/lib/electrum_wallet.dart
+++ b/cw_bitcoin/lib/electrum_wallet.dart
@@ -68,12 +68,12 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
            ? {currency: initialBalance ?? const ElectrumBalance(confirmed: 0, unconfirmed: 0)}
            : {}),
         this.unspentCoinsInfo = unspentCoinsInfo,
-        feeEstimate = ElectrumFeeEstimate(this),
         super(walletInfo) {
     this.electrumClient = electrumClient ?? ElectrumClient();
     this.walletInfo = walletInfo;
     transactionHistory =
         ElectrumTransactionHistory(walletInfo: walletInfo, password: password);
+    feeEstimate = ElectrumFeeEstimate(this);
   }
 
   static int estimatedTransactionSize(int inputsCount, int outputsCounts) =>
@@ -98,7 +98,7 @@ abstract class ElectrumWalletBase extends WalletBase<ElectrumBalance,
 
   @override
   @observable
-  ElectrumFeeEstimate feeEstimate;
+  late ElectrumFeeEstimate feeEstimate;
 
   List<String> get scriptHashes => walletAddresses.addresses
       .map((addr) => scriptHash(addr.address, networkType: networkType))
diff --git a/cw_core/lib/fee_estimate.dart b/cw_core/lib/fee_estimate.dart
index 862040745..d577d2e09 100644
--- a/cw_core/lib/fee_estimate.dart
+++ b/cw_core/lib/fee_estimate.dart
@@ -2,9 +2,9 @@ import 'package:cw_core/transaction_priority.dart';
 
 abstract class FeeEstimate
 {
-  void update({TransactionPriority priority, int outputsCount});
+  void update({required TransactionPriority priority, int outputsCount = 1});
 
-  int get({TransactionPriority priority, int amount, int outputsCount});
+  int get({required TransactionPriority priority, required int amount, int outputsCount = 1});
 
-  void set({TransactionPriority priority, int outputsCount, int fee});
+  void set({required TransactionPriority priority, required int outputsCount, required int fee});
 }
\ No newline at end of file
diff --git a/cw_haven/lib/api/wallet.dart b/cw_haven/lib/api/wallet.dart
index db6163afe..3abb6e9c0 100644
--- a/cw_haven/lib/api/wallet.dart
+++ b/cw_haven/lib/api/wallet.dart
@@ -366,6 +366,6 @@ int _estimateTransactionFee(Map args) {
   return estimateTransactionFeeSync(outputsCount, priorityRaw);
 }
 
-Future<int> estimateTransactionFee({int priorityRaw, int outputsCount}) {
+Future<int> estimateTransactionFee({required int priorityRaw, required int outputsCount}) {
   return compute(_estimateTransactionFee, {'priorityRaw': priorityRaw, 'outputsCount': outputsCount});
 }
\ No newline at end of file
diff --git a/cw_haven/lib/haven_fee_estimate.dart b/cw_haven/lib/haven_fee_estimate.dart
index 826690887..80ed775a6 100644
--- a/cw_haven/lib/haven_fee_estimate.dart
+++ b/cw_haven/lib/haven_fee_estimate.dart
@@ -15,7 +15,7 @@ abstract class _HavenFeeEstimate extends FeeEstimate with Store {
   ObservableMap<String, int> _estimatedFee;
 
   @override
-  void update({TransactionPriority priority, int outputsCount}) {
+  void update({required TransactionPriority priority, int outputsCount = 1}) {
     Future(() async {
       final fee = await haven_wallet.estimateTransactionFee(priorityRaw: priority.raw, outputsCount: outputsCount);
       set(priority: priority, fee: fee, outputsCount: outputsCount);
@@ -23,12 +23,12 @@ abstract class _HavenFeeEstimate extends FeeEstimate with Store {
   }
 
   @override
-  int get({TransactionPriority priority, int amount, int outputsCount}) {
+  int get({required TransactionPriority priority, required int amount, int outputsCount = 1}) {
     return _estimatedFee[_key(priority, outputsCount)] ?? 0;
   }
 
   @override
-  void set({TransactionPriority priority, int outputsCount, int fee}) {
+  void set({required TransactionPriority priority, required int outputsCount, required int fee}) {
     _estimatedFee[_key(priority, outputsCount)] = fee;
   }
 
diff --git a/cw_haven/lib/haven_wallet.dart b/cw_haven/lib/haven_wallet.dart
index e6c18edce..646ac199f 100644
--- a/cw_haven/lib/haven_wallet.dart
+++ b/cw_haven/lib/haven_wallet.dart
@@ -42,6 +42,7 @@ abstract class HavenWalletBase extends WalletBase<MoneroBalance,
         _hasSyncAfterStartup = false,
         walletAddresses = HavenWalletAddresses(walletInfo),
         syncStatus = NotConnectedSyncStatus(),
+        feeEstimate = HavenFeeEstimate(),
         super(walletInfo) {
     transactionHistory = HavenTransactionHistory();
     _onAccountChangeReaction = reaction((_) => walletAddresses.account,
@@ -52,7 +53,6 @@ abstract class HavenWalletBase extends WalletBase<MoneroBalance,
       balance.addAll(getHavenBalance(accountIndex: account.id));
       walletAddresses.updateSubaddressList(accountIndex: account.id);
     });
-    feeEstimate = HavenFeeEstimate();
   }
 
   static const int _autoSaveInterval = 30;
diff --git a/cw_monero/lib/api/wallet.dart b/cw_monero/lib/api/wallet.dart
index 3d2a67a26..427e1bcc9 100644
--- a/cw_monero/lib/api/wallet.dart
+++ b/cw_monero/lib/api/wallet.dart
@@ -376,6 +376,6 @@ int _estimateTransactionFee(Map args) {
   return estimateTransactionFeeSync(outputsCount, priorityRaw);
 }
 
-Future<int> estimateTransactionFee({int priorityRaw, int outputsCount}) {
-  return compute(_estimateTransactionFee, {'priorityRaw': priorityRaw, 'outputsCount': outputsCount});
+Future<int> estimateTransactionFee({required int priorityRaw, int? outputsCount}) {
+  return compute(_estimateTransactionFee, {'priorityRaw': priorityRaw, 'outputsCount': outputsCount ?? 1});
 }
\ No newline at end of file
diff --git a/cw_monero/lib/monero_fee_estimate.dart b/cw_monero/lib/monero_fee_estimate.dart
index c32ad3bf2..db9904958 100644
--- a/cw_monero/lib/monero_fee_estimate.dart
+++ b/cw_monero/lib/monero_fee_estimate.dart
@@ -15,7 +15,7 @@ abstract class _MoneroFeeEstimate extends FeeEstimate with Store {
   ObservableMap<String, int> _estimatedFee;
 
   @override
-  void update({TransactionPriority priority, int outputsCount}) {
+  void update({required TransactionPriority priority, int outputsCount = 1}) {
     Future(() async {
       final fee = await monero_wallet.estimateTransactionFee(priorityRaw: priority.raw, outputsCount: outputsCount);
       set(priority: priority, fee: fee, outputsCount: outputsCount);
@@ -23,12 +23,12 @@ abstract class _MoneroFeeEstimate extends FeeEstimate with Store {
   }
 
   @override
-  int get({TransactionPriority priority, int amount, int outputsCount}) {
+  int get({required TransactionPriority priority, required int amount, int outputsCount = 1}) {
     return _estimatedFee[_key(priority, outputsCount)] ?? 0;
   }
 
   @override
-  void set({TransactionPriority priority, int outputsCount, int fee}) {
+  void set({required TransactionPriority priority, required int outputsCount, required int fee}) {
     _estimatedFee[_key(priority, outputsCount)] = fee;
   }
 
diff --git a/cw_monero/lib/monero_wallet.dart b/cw_monero/lib/monero_wallet.dart
index 89b257dd3..a32288d43 100644
--- a/cw_monero/lib/monero_wallet.dart
+++ b/cw_monero/lib/monero_wallet.dart
@@ -1,4 +1,6 @@
 import 'dart:async';
+import 'package:cw_core/monero_balance.dart';
+import 'package:cw_core/monero_wallet_keys.dart';
 import 'package:cw_core/transaction_priority.dart';
 import 'package:cw_core/monero_amount_format.dart';
 import 'package:cw_monero/monero_transaction_creation_exception.dart';
@@ -16,8 +18,6 @@ import 'package:cw_monero/api/transaction_history.dart' as transaction_history;
 import 'package:cw_monero/api/monero_output.dart';
 import 'package:cw_monero/monero_transaction_creation_credentials.dart';
 import 'package:cw_monero/pending_monero_transaction.dart';
-import 'package:cw_monero/monero_wallet_keys.dart';
-import 'package:cw_monero/monero_balance.dart';
 import 'package:cw_monero/monero_fee_estimate.dart';
 import 'package:cw_monero/monero_transaction_history.dart';
 import 'package:cw_core/account.dart';
@@ -26,7 +26,6 @@ import 'package:cw_core/wallet_base.dart';
 import 'package:cw_core/sync_status.dart';
 import 'package:cw_core/wallet_info.dart';
 import 'package:cw_core/node.dart';
-import 'package:cw_core/monero_transaction_priority.dart';
 import 'package:cw_core/crypto_currency.dart';
 
 part 'monero_wallet.g.dart';
@@ -47,6 +46,7 @@ abstract class MoneroWalletBase extends WalletBase<MoneroBalance,
         _hasSyncAfterStartup = false,
         walletAddresses = MoneroWalletAddresses(walletInfo),
         syncStatus = NotConnectedSyncStatus(),
+        feeEstimate = MoneroFeeEstimate(),
         super(walletInfo) {
     transactionHistory = MoneroTransactionHistory();
     _onAccountChangeReaction = reaction((_) => walletAddresses.account,
@@ -64,7 +64,6 @@ abstract class MoneroWalletBase extends WalletBase<MoneroBalance,
         });
       walletAddresses.updateSubaddressList(accountIndex: account.id);
     });
-    feeEstimate = MoneroFeeEstimate();
   }
 
   static const int _autoSaveInterval = 30;
diff --git a/lib/entities/format_amount.dart b/lib/entities/format_amount.dart
index 50cc92d9f..ef67214d4 100644
--- a/lib/entities/format_amount.dart
+++ b/lib/entities/format_amount.dart
@@ -11,13 +11,13 @@ String formatAmount(String amount) {
   return amount;
 }
 
-double formatAmountToDouble({WalletType type, int amount}) {
+double formatAmountToDouble({required WalletType type, required int amount}) {
   if (type == WalletType.bitcoin || type == WalletType.litecoin) {
-    return bitcoin.formatterBitcoinAmountToDouble(amount: amount);
+    return bitcoin!.formatterBitcoinAmountToDouble(amount: amount);
   }
 
   if (type == WalletType.monero) {
-    return monero.formatterMoneroAmountToDouble(amount: amount);
+    return monero!.formatterMoneroAmountToDouble(amount: amount);
   }
 
   return 0.0;
diff --git a/lib/reactions/on_wallet_sync_status_change.dart b/lib/reactions/on_wallet_sync_status_change.dart
index 981778357..a86a72c33 100644
--- a/lib/reactions/on_wallet_sync_status_change.dart
+++ b/lib/reactions/on_wallet_sync_status_change.dart
@@ -38,7 +38,7 @@ void startWalletSyncStatusChangeReaction(WalletBase<Balance, TransactionHistoryB
     }
 
     if (status is SyncedSyncStatus) {
-      wallet.feeEstimate.update(priority: settingsStore.priority[wallet.type], outputsCount: 1);
+      wallet.feeEstimate.update(priority: settingsStore.priority[wallet.type]!);
     }
   });
 }
diff --git a/lib/src/screens/ionia/cards/ionia_buy_card_detail_page.dart b/lib/src/screens/ionia/cards/ionia_buy_card_detail_page.dart
index 4b9f0a220..337652fca 100644
--- a/lib/src/screens/ionia/cards/ionia_buy_card_detail_page.dart
+++ b/lib/src/screens/ionia/cards/ionia_buy_card_detail_page.dart
@@ -312,10 +312,10 @@ class IoniaBuyGiftCardDetailPage extends BasePage {
                 '${ioniaPurchaseViewModel.sendViewModel.fiat.title}',
             fee: S.of(context).send_fee,
             feeValue:
-            '${ioniaPurchaseViewModel.sendViewModel.outputs.first.estimatedFee} '
+            '${ioniaPurchaseViewModel.sendViewModel.estimatedFee} '
                 '${ioniaPurchaseViewModel.invoice!.chain}',
             feeFiatAmount:
-            '${ioniaPurchaseViewModel.sendViewModel.outputs.first.estimatedFeeFiatAmount} '
+            '${ioniaPurchaseViewModel.sendViewModel.estimatedFeeFiatAmount} '
                 '${ioniaPurchaseViewModel.sendViewModel.fiat.title}',
             outputs: ioniaPurchaseViewModel.sendViewModel.outputs,
             rightButtonText: S.of(context).ok,
diff --git a/lib/view_model/exchange/exchange_view_model.dart b/lib/view_model/exchange/exchange_view_model.dart
index d1897ddfc..cd334d03d 100644
--- a/lib/view_model/exchange/exchange_view_model.dart
+++ b/lib/view_model/exchange/exchange_view_model.dart
@@ -488,8 +488,7 @@ abstract class ExchangeViewModelBase with Store {
     if (wallet.type == WalletType.bitcoin) {
       final availableBalance = wallet.balance[wallet.currency]!.available;
       final priority = _settingsStore.priority[wallet.type]!;
-      final fee = wallet.calculateEstimatedFee(priority, null);
-      final fee = wallet.feeEstimate.get(priority: priority);
+      final fee = wallet.feeEstimate.get(priority: priority, amount: availableBalance);
 
       if (availableBalance < fee || availableBalance == 0) {
         return;
diff --git a/lib/view_model/send/output.dart b/lib/view_model/send/output.dart
index 0901f6529..7b6ec9ca7 100644
--- a/lib/view_model/send/output.dart
+++ b/lib/view_model/send/output.dart
@@ -150,7 +150,9 @@ abstract class OutputBase with Store {
     try {
       final fiat = calculateFiatAmount(
           price: _fiatConversationStore.prices[cryptoCurrencyHandler()]!,
-          cryptoAmount: (cryptoAmount.toUpperCase() == S.current.all) ? _cryptoNumberFormat.format(formatAmountToDouble(type: _wallet.type, amount: _estimateAmountAll())) : cryptoAmount.replaceAll(',', '.'));
+          cryptoAmount: (cryptoAmount.toUpperCase() == S.current.all)
+              ? _cryptoNumberFormat.format(formatAmountToDouble(type: _wallet.type, amount: _estimateAmountAll()))
+              : cryptoAmount.replaceAll(',', '.'));
       if (fiatAmount != fiat) {
         fiatAmount = fiat;
       }
@@ -198,8 +200,11 @@ abstract class OutputBase with Store {
   }
 
   int _estimateAmountAll() {
-    final fee = _wallet.feeEstimate.get(priority: _settingsStore.priority[_wallet.type], outputsCount: 1);
-    return max(0, _wallet.balance[cryptoCurrencyHandler()].available - fee);
+    final fee = _wallet.feeEstimate.get(
+      priority: _settingsStore.priority[_wallet.type]!,
+      amount: _wallet.balance[cryptoCurrencyHandler()]!.available,
+    );
+    return max(0, _wallet.balance[cryptoCurrencyHandler()]!.available - fee);
   }
 
   Future<void> fetchParsedAddress(BuildContext context) async {
diff --git a/lib/view_model/send/send_view_model.dart b/lib/view_model/send/send_view_model.dart
index ff77ab892..93476c6e1 100644
--- a/lib/view_model/send/send_view_model.dart
+++ b/lib/view_model/send/send_view_model.dart
@@ -54,7 +54,9 @@ abstract class SendViewModelBase with Store {
     outputs.add(Output(_wallet, _settingsStore, _fiatConversationStore, () => selectedCryptoCurrency));
 
     _settingsStore.priority.observe((change) async {
-      _wallet.feeEstimate.update(priority: change.newValue, outputsCount: outputs.length);
+      if (change.newValue != null) {
+        _wallet.feeEstimate.update(priority: change.newValue!, outputsCount: outputs.length);
+      }
     });
 
     estimateFee();
@@ -90,7 +92,7 @@ abstract class SendViewModelBase with Store {
   String get pendingTransactionFiatAmount {
     try {
       if (pendingTransaction != null) {
-        return _calculateFiatAmount(pendingTransaction.amountFormatted);
+        return _calculateFiatAmount(pendingTransaction!.amountFormatted);
       } else {
         return '0.00';
       }
@@ -103,7 +105,7 @@ abstract class SendViewModelBase with Store {
   String get pendingTransactionFeeFiatAmount {
     try {
       if (pendingTransaction != null) {
-        return _calculateFiatAmount(pendingTransaction.feeFormatted);
+        return _calculateFiatAmount(pendingTransaction!.feeFormatted);
       } else {
         return '0.00';
       }
@@ -292,7 +294,7 @@ abstract class SendViewModelBase with Store {
       currency.toLowerCase() == _wallet.currency.title.toLowerCase();
 
   void estimateFee() {
-    _wallet.feeEstimate.update(priority: _settingsStore.priority[_wallet.type], outputsCount: outputs.length);
+    _wallet.feeEstimate.update(priority: _settingsStore.priority[_wallet.type]!, outputsCount: outputs.length);
   }
 
   @computed
@@ -304,7 +306,7 @@ abstract class SendViewModelBase with Store {
       }
 
       final fee = _wallet.feeEstimate.get(
-        priority: _settingsStore.priority[_wallet.type],
+        priority: _settingsStore.priority[_wallet.type]!,
         amount: totalFormattedCryptoAmount,
         outputsCount: outputs.length,
       );