diff --git a/lib/api/api.js b/lib/api/api.js
index f1b32e61bb..aea4bb81aa 100644
--- a/lib/api/api.js
+++ b/lib/api/api.js
@@ -147,7 +147,7 @@ const api = {
         const requestContexts = prepareRequestContexts(apiMethod, request,
             sourceBucket, sourceObject, sourceVersionId);
 
-        if (apiMethod === 'completeMultipartUpload' || apiMethod === 'abortMultipartUpload') {
+        if (apiMethod === 'completeMultipartUpload' || apiMethod === 'multipartDelete') {
             // Request account quotas explicitly for MPU requests, to consider parts cleanup
             // NOTE: we need quota for these, but it will be evaluated at the end of the API,
             // once the parts have actually been deleted (not via standardMetadataValidateBucketAndObj)
diff --git a/lib/api/apiUtils/object/abortMultipartUpload.js b/lib/api/apiUtils/object/abortMultipartUpload.js
index c860c5a7f1..be12659723 100644
--- a/lib/api/apiUtils/object/abortMultipartUpload.js
+++ b/lib/api/apiUtils/object/abortMultipartUpload.js
@@ -140,7 +140,7 @@ function abortMultipartUpload(authInfo, bucketName, objectKey, uploadId, log,
                     cb();
                 });
             }, () => {
-                const length = locations.reduce((length, loc) => length + loc.size, 0);
+                const length = storedParts.reduce((length, loc) => length + loc.value.Size, 0);
                 return validateQuotas(request, destBucket, request.accountQuotas,
                     ['objectDelete'], 'objectDelete', -length, false, log, err => {
                         if (err) {
diff --git a/lib/api/completeMultipartUpload.js b/lib/api/completeMultipartUpload.js
index 5117349a19..c499dec0e3 100644
--- a/lib/api/completeMultipartUpload.js
+++ b/lib/api/completeMultipartUpload.js
@@ -214,12 +214,13 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                         return next(err, destBucket);
                     }
                     const storedParts = result.Contents;
+                    const totalMPUSize = storedParts.reduce((acc, part) => acc + part.value.Size, 0);
                     return next(null, destBucket, objMD, mpuBucket, storedParts,
-                        jsonList, storedMetadata, location, mpuOverviewKey);
+                        jsonList, storedMetadata, location, mpuOverviewKey, totalMPUSize);
                 });
         },
         function completeExternalMpu(destBucket, objMD, mpuBucket, storedParts,
-        jsonList, storedMetadata, location, mpuOverviewKey, next) {
+        jsonList, storedMetadata, location, mpuOverviewKey, totalMPUSize, next) {
             const mdInfo = { storedParts, mpuOverviewKey, splitter };
             const mpuInfo =
                 { objectKey, uploadId, jsonList, bucketName, destBucket };
@@ -237,16 +238,17 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                 }
                 // if mpu not handled externally, completeObjData will be null
                 return next(null, destBucket, objMD, mpuBucket, storedParts,
-                    jsonList, storedMetadata, completeObjData, mpuOverviewKey);
+                    jsonList, storedMetadata, completeObjData, mpuOverviewKey,
+                    totalMPUSize);
             });
         },
         function validateAndFilterParts(destBucket, objMD, mpuBucket,
         storedParts, jsonList, storedMetadata, completeObjData, mpuOverviewKey,
-        next) {
+        totalMPUSize, next) {
             if (completeObjData) {
                 return next(null, destBucket, objMD, mpuBucket, storedParts,
                 jsonList, storedMetadata, completeObjData, mpuOverviewKey,
-                completeObjData.filteredPartsObj);
+                completeObjData.filteredPartsObj, totalMPUSize);
             }
             const filteredPartsObj = validateAndFilterMpuParts(storedParts,
                 jsonList, mpuOverviewKey, splitter, log);
@@ -255,11 +257,11 @@ function completeMultipartUpload(authInfo, request, log, callback) {
             }
             return next(null, destBucket, objMD, mpuBucket, storedParts,
                 jsonList, storedMetadata, completeObjData, mpuOverviewKey,
-                filteredPartsObj);
+                filteredPartsObj, totalMPUSize);
         },
         function processParts(destBucket, objMD, mpuBucket, storedParts,
         jsonList, storedMetadata, completeObjData, mpuOverviewKey,
-        filteredPartsObj, next) {
+        filteredPartsObj, totalMPUSize, next) {
             // if mpu was completed on backend that stored mpu MD externally,
             // skip MD processing steps
             if (completeObjData && skipMpuPartProcessing(completeObjData)) {
@@ -277,7 +279,7 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                 const calculatedSize = completeObjData.contentLength;
                 return next(null, destBucket, objMD, mpuBucket, storedMetadata,
                     completeObjData.eTag, calculatedSize, dataLocations,
-                    [mpuOverviewKey], null, completeObjData);
+                    [mpuOverviewKey], null, completeObjData, totalMPUSize);
             }
 
             const partsInfo =
@@ -301,15 +303,15 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                 ];
                 return next(null, destBucket, objMD, mpuBucket, storedMetadata,
                     aggregateETag, calculatedSize, dataLocations, keysToDelete,
-                    extraPartLocations, completeObjData);
+                    extraPartLocations, completeObjData, totalMPUSize);
             }
             return next(null, destBucket, objMD, mpuBucket, storedMetadata,
                 aggregateETag, calculatedSize, dataLocations, keysToDelete,
-                extraPartLocations, null);
+                extraPartLocations, null, totalMPUSize);
         },
         function prepForStoring(destBucket, objMD, mpuBucket, storedMetadata,
             aggregateETag, calculatedSize, dataLocations, keysToDelete,
-            extraPartLocations, completeObjData, next) {
+            extraPartLocations, completeObjData, totalMPUSize, next) {
             const metaHeaders = {};
             const keysNotNeeded =
                 ['initiator', 'partLocations', 'key',
@@ -322,6 +324,8 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                 metaHeaders[item] = storedMetadata[item];
             });
 
+            const droppedMPUSize = totalMPUSize - calculatedSize;
+
             const metaStoreParams = {
                 authInfo,
                 objectKey,
@@ -381,7 +385,7 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                 return process.nextTick(() => next(null, destBucket, dataLocations,
                     metaStoreParams, mpuBucket, keysToDelete, aggregateETag,
                     objMD, extraPartLocations, pseudoCipherBundle,
-                    completeObjData, options));
+                    completeObjData, options, droppedMPUSize));
             }
 
             if (!destBucket.isVersioningEnabled() && objMD?.archive?.archiveInfo) {
@@ -404,13 +408,13 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                     return next(null, destBucket, dataLocations,
                         metaStoreParams, mpuBucket, keysToDelete, aggregateETag,
                         objMD, extraPartLocations, pseudoCipherBundle,
-                        completeObjData, options);
+                        completeObjData, options, droppedMPUSize);
                 });
         },
         function storeAsNewObj(destinationBucket, dataLocations,
             metaStoreParams, mpuBucket, keysToDelete, aggregateETag, objMD,
             extraPartLocations, pseudoCipherBundle,
-            completeObjData, options, next) {
+            completeObjData, options, droppedMPUSize, next) {
             const dataToDelete = options.dataToDelete;
             /* eslint-disable no-param-reassign */
             metaStoreParams.versionId = options.versionId;
@@ -462,7 +466,7 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                     return next(null, mpuBucket, keysToDelete, aggregateETag,
                         extraPartLocations, destinationBucket,
                         // pass the original version ID as generatedVersionId
-                        objMD.versionId);
+                        objMD.versionId, droppedMPUSize);
                 }
             }
             return services.metadataStoreObject(destinationBucket.getName(),
@@ -500,31 +504,31 @@ function completeMultipartUpload(authInfo, request, log, callback) {
                                 }
                                 return next(null, mpuBucket, keysToDelete,
                                     aggregateETag, extraPartLocations,
-                                    destinationBucket, generatedVersionId);
+                                    destinationBucket, generatedVersionId,
+                                    droppedMPUSize);
                             });
                     }
                     return next(null, mpuBucket, keysToDelete, aggregateETag,
                         extraPartLocations, destinationBucket,
-                        generatedVersionId);
+                        generatedVersionId, droppedMPUSize);
                 });
         },
         function deletePartsMetadata(mpuBucket, keysToDelete, aggregateETag,
-            extraPartLocations, destinationBucket, generatedVersionId, next) {
+            extraPartLocations, destinationBucket, generatedVersionId, droppedMPUSize, next) {
             services.batchDeleteObjectMetadata(mpuBucket.getName(),
                 keysToDelete, log, err => next(err, extraPartLocations,
-                    destinationBucket, aggregateETag, generatedVersionId));
+                    destinationBucket, aggregateETag, generatedVersionId, droppedMPUSize));
         },
         function batchDeleteExtraParts(extraPartLocations, destinationBucket,
-            aggregateETag, generatedVersionId, next) {
+            aggregateETag, generatedVersionId, droppedMPUSize, next) {
             if (extraPartLocations && extraPartLocations.length > 0) {
                 return data.batchDelete(extraPartLocations, request.method, null, log, err => {
                     if (err) {
                         return next(err);
                     }
 
-                    const length = extraPartLocations.reduce((length, loc) => length + loc.size, 0);
                     return validateQuotas(request, destinationBucket, request.accountQuotas,
-                        ['objectDelete'], 'objectDelete', -length, false, log, err => {
+                        ['objectDelete'], 'objectDelete', -droppedMPUSize, false, log, err => {
                             if (err) {
                                 // Ignore error, as the data has been deleted already: only inflight count
                                 // has not been updated, and will be eventually consistent anyway