diff --git a/packages/extension-base/src/koni/background/handlers/Extension.ts b/packages/extension-base/src/koni/background/handlers/Extension.ts
index b7b130374f..f27e77bda9 100644
--- a/packages/extension-base/src/koni/background/handlers/Extension.ts
+++ b/packages/extension-base/src/koni/background/handlers/Extension.ts
@@ -3,6 +3,7 @@
 
 import { Common } from '@ethereumjs/common';
 import { LegacyTransaction } from '@ethereumjs/tx';
+import { COMMON_CHAIN_SLUGS } from '@subwallet/chain-list';
 import { _AssetRef, _AssetType, _ChainAsset, _ChainInfo, _MultiChainAsset } from '@subwallet/chain-list/types';
 import { TransactionError } from '@subwallet/extension-base/background/errors/TransactionError';
 import { withErrorLog } from '@subwallet/extension-base/background/handlers/helpers';
@@ -37,8 +38,8 @@ import { _isPolygonChainBridge, getClaimPolygonBridge, isClaimedPolygonBridge }
 import { _isPosChainBridge, getClaimPosBridge } from '@subwallet/extension-base/services/balance-service/transfer/xcm/posBridge';
 import { _API_OPTIONS_CHAIN_GROUP, _DEFAULT_MANTA_ZK_CHAIN, _MANTA_ZK_CHAIN_GROUP, _ZK_ASSET_PREFIX, SUFFICIENT_CHAIN } from '@subwallet/extension-base/services/chain-service/constants';
 import { _ChainApiStatus, _ChainConnectionStatus, _ChainState, _NetworkUpsertParams, _SubstrateAdapterQueryArgs, _SubstrateApi, _ValidateCustomAssetRequest, _ValidateCustomAssetResponse, EnableChainParams, EnableMultiChainParams } from '@subwallet/extension-base/services/chain-service/types';
-import { _getAssetDecimals, _getAssetSymbol, _getChainNativeTokenBasicInfo, _getContractAddressOfToken, _getEvmChainId, _getTokenOnChainAssetId, _getXcmAssetMultilocation, _isAssetSmartContractNft, _isBridgedToken, _isChainEvmCompatible, _isChainSubstrateCompatible, _isChainTonCompatible, _isCustomAsset, _isLocalToken, _isMantaZkAsset, _isNativeToken, _isPureEvmChain, _isTokenEvmSmartContract, _isTokenTransferredByEvm, _isTokenTransferredByTon } from '@subwallet/extension-base/services/chain-service/utils';
-import { _NotificationInfo, ClaimPolygonBridgeNotificationMetadata, NotificationSetup } from '@subwallet/extension-base/services/inapp-notification-service/interfaces';
+import { _getAssetDecimals, _getAssetSymbol, _getChainNativeTokenBasicInfo, _getContractAddressOfToken, _getEvmChainId, _getTokenMinAmount, _getTokenOnChainAssetId, _getXcmAssetMultilocation, _isAssetSmartContractNft, _isBridgedToken, _isChainEvmCompatible, _isChainSubstrateCompatible, _isChainTonCompatible, _isCustomAsset, _isLocalToken, _isMantaZkAsset, _isNativeToken, _isPureEvmChain, _isTokenEvmSmartContract, _isTokenTransferredByEvm, _isTokenTransferredByTon } from '@subwallet/extension-base/services/chain-service/utils';
+import { ClaimPolygonBridgeNotificationMetadata, NotificationSetup } from '@subwallet/extension-base/services/inapp-notification-service/interfaces';
 import { AppBannerData, AppConfirmationData, AppPopupData } from '@subwallet/extension-base/services/mkt-campaign-service/types';
 import { EXTENSION_REQUEST_URL } from '@subwallet/extension-base/services/request-service/constants';
 import { AuthUrls } from '@subwallet/extension-base/services/request-service/types';
@@ -54,7 +55,7 @@ import { RequestClaimBridge } from '@subwallet/extension-base/types/bridge';
 import { GetNotificationParams, RequestIsClaimedPolygonBridge, RequestSwitchStatusParams } from '@subwallet/extension-base/types/notification';
 import { CommonOptimalPath } from '@subwallet/extension-base/types/service-base';
 import { SwapPair, SwapQuoteResponse, SwapRequest, SwapRequestResult, SwapSubmitParams, ValidateSwapProcessParams } from '@subwallet/extension-base/types/swap';
-import { _analyzeAddress, BN_ZERO, combineAllAccountProxy, createTransactionFromRLP, isSameAddress, MODULE_SUPPORT, reformatAddress, signatureToHex, Transaction as QrTransaction, transformAccounts, transformAddresses, uniqueStringArray } from '@subwallet/extension-base/utils';
+import { _analyzeAddress, BN_ZERO, combineAllAccountProxy, createTransactionFromRLP, isSameAddress, MODULE_SUPPORT, reformatAddress, signatureToHex, toBNString, Transaction as QrTransaction, transformAccounts, transformAddresses, uniqueStringArray } from '@subwallet/extension-base/utils';
 import { parseContractInput, parseEvmRlp } from '@subwallet/extension-base/utils/eth/parseTransaction';
 import { metadataExpand } from '@subwallet/extension-chains';
 import { MetadataDef } from '@subwallet/extension-inject/types';
@@ -1783,6 +1784,10 @@ export default class KoniExtension {
     const destinationTokenInfo = this.#koniState.getXcmEqualAssetByChain(destChain, originTokenInfo.slug);
     const existentialDeposit = originTokenInfo.minAmount || '0';
 
+    // todo: improve this case. Currently set 1 AVAIL for covering fee as default.
+    const isSpecialBridgeFromAvail = originTokenInfo.slug === 'avail_mainnet-NATIVE-AVAIL' && destChain === COMMON_CHAIN_SLUGS.ETHEREUM;
+    const specialBridgeFromAvailFee = new BigN(toBNString(1, _getAssetDecimals(originTokenInfo))).minus(new BigN(_getTokenMinAmount(originTokenInfo)));
+
     if (destinationTokenInfo) {
       const [bnMockExecutionFee, { value }] = await Promise.all([
         getXcmMockTxFee(substrateApi, chainInfoMap, originTokenInfo, destinationTokenInfo),
@@ -1790,7 +1795,7 @@ export default class KoniExtension {
       ]);
 
       const bnMaxTransferable = new BigN(value);
-      const estimatedFee = bnMockExecutionFee.multipliedBy(XCM_FEE_RATIO).plus(new BigN(existentialDeposit));
+      const estimatedFee = isSpecialBridgeFromAvail ? specialBridgeFromAvailFee : bnMockExecutionFee.multipliedBy(XCM_FEE_RATIO).plus(new BigN(existentialDeposit));
 
       return bnMaxTransferable.minus(estimatedFee);
     }
diff --git a/packages/extension-base/src/utils/number.ts b/packages/extension-base/src/utils/number.ts
index c442672412..9d95cb670e 100644
--- a/packages/extension-base/src/utils/number.ts
+++ b/packages/extension-base/src/utils/number.ts
@@ -234,6 +234,12 @@ export const PREDEFINED_FORMATTER: Record<string, NumberFormatter> = {
   balance: balanceFormatter
 };
 
+export const toBNString = (input: string | number | BigNumber, decimal: number): string => {
+  const raw = new BigNumber(input);
+
+  return raw.multipliedBy(BN_TEN.pow(decimal)).toFixed();
+};
+
 /** @function formatNumber
  * Convert number to a formatted string by dividing by 10^decimal
  * @param {string | number | BigNumber} input - Input number