diff --git a/CRM/Contact/Form/Merge.php b/CRM/Contact/Form/Merge.php
index 91f282f6bb4e..da804021ea2c 100644
--- a/CRM/Contact/Form/Merge.php
+++ b/CRM/Contact/Form/Merge.php
@@ -114,7 +114,7 @@ public function preProcess() {
         CRM_Core_Session::singleton()->pushUserContext($browseUrl);
       }
 
-      $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $gid, json_decode($this->criteria, TRUE));
+      $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $gid, json_decode($this->criteria, TRUE), TRUE, $this->limit);
 
       $join = CRM_Dedupe_Merger::getJoinOnDedupeTable();
       $where = "de.id IS NULL";
@@ -331,7 +331,7 @@ public function postProcess() {
     }
 
     if ($this->next && $this->_mergeId) {
-      $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $this->_gid, json_decode($this->criteria, TRUE));
+      $cacheKey = CRM_Dedupe_Merger::getMergeCacheKeyString($this->_rgid, $this->_gid, json_decode($this->criteria, TRUE), TRUE, $this->limit);
 
       $join = CRM_Dedupe_Merger::getJoinOnDedupeTable();
       $where = "de.id IS NULL";
diff --git a/CRM/Contact/Page/AJAX.php b/CRM/Contact/Page/AJAX.php
index 7dcedcc8cd5f..3ac0326cf743 100644
--- a/CRM/Contact/Page/AJAX.php
+++ b/CRM/Contact/Page/AJAX.php
@@ -638,6 +638,7 @@ public static function getDedupes() {
 
     $gid = CRM_Utils_Request::retrieve('gid', 'Positive');
     $rgid = CRM_Utils_Request::retrieve('rgid', 'Positive');
+    $limit = CRM_Utils_Request::retrieveValue('limit', 'Positive', 0);
     $null = NULL;
     $criteria = CRM_Utils_Request::retrieve('criteria', 'Json', $null, FALSE, '{}');
     $selected = CRM_Utils_Request::retrieveValue('selected', 'Boolean');
@@ -646,7 +647,7 @@ public static function getDedupes() {
     }
 
     $whereClause = $orderByClause = '';
-    $cacheKeyString   = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, json_decode($criteria, TRUE));
+    $cacheKeyString   = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, json_decode($criteria, TRUE), TRUE, $limit);
 
     $searchRows = [];
 
diff --git a/CRM/Contact/Page/DedupeFind.php b/CRM/Contact/Page/DedupeFind.php
index 8b22a7140d92..b7a22ea66611 100644
--- a/CRM/Contact/Page/DedupeFind.php
+++ b/CRM/Contact/Page/DedupeFind.php
@@ -105,13 +105,13 @@ public function run() {
       'reset' => 1,
       'rgid' => $rgid,
       'gid' => $gid,
-      'limit' => $limit,
+      'limit' => (int) $limit,
       'criteria' => $criteria,
     ];
     $this->assign('urlQuery', CRM_Utils_System::makeQueryString($urlQry));
     $this->assign('isSelected', $this->isSelected());
     $criteria = json_decode($criteria, TRUE);
-    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria);
+    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria, TRUE, $limit);
     $this->assign('cacheKey', $cacheKeyString);
 
     if ($context == 'search') {
@@ -129,7 +129,7 @@ public function run() {
     }
     elseif ($action & CRM_Core_Action::MAP) {
       // do a batch merge if requested
-      $result = CRM_Dedupe_Merger::batchMerge($rgid, $gid, 'safe', 75, 2, $criteria);
+      $result = CRM_Dedupe_Merger::batchMerge($rgid, $gid, 'safe', 75, 2, $criteria, TRUE, NULL, $limit);
 
       $skippedCount = CRM_Utils_Request::retrieve('skipped', 'Positive', $this, FALSE, 0);
       $skippedCount = $skippedCount + count($result['skipped']);
diff --git a/CRM/Contact/Page/DedupeMerge.php b/CRM/Contact/Page/DedupeMerge.php
index 1dddf5619470..348f65b1d8f8 100644
--- a/CRM/Contact/Page/DedupeMerge.php
+++ b/CRM/Contact/Page/DedupeMerge.php
@@ -70,7 +70,7 @@ public static function getRunner() {
     ];
 
     $criteria = json_decode($criteria, TRUE);
-    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria);
+    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria, TRUE, $limit);
 
     if ($mode == 'aggressive' && !CRM_Core_Permission::check('force merge duplicate contacts')) {
       CRM_Core_Session::setStatus(ts('You do not have permission to force merge duplicate contact records'), ts('Permission Denied'), 'error');
@@ -98,7 +98,7 @@ public static function getRunner() {
     for ($i = 1; $i <= ceil($total / self::BATCHLIMIT); $i++) {
       $task = new CRM_Queue_Task(
         ['CRM_Contact_Page_DedupeMerge', 'callBatchMerge'],
-        [$rgid, $gid, $mode, self::BATCHLIMIT, $onlyProcessSelected, $criteria],
+        [$rgid, $gid, $mode, self::BATCHLIMIT, $onlyProcessSelected, $criteria, $limit],
         "Processed " . $i * self::BATCHLIMIT . " pair of duplicates out of " . $total
       );
 
@@ -132,11 +132,15 @@ public static function getRunner() {
    * @param int $batchLimit
    * @param int $isSelected
    * @param array $criteria
+   * @param int $searchLimit
    *
    * @return int
+   *
+   * @throws \CRM_Core_Exception
+   * @throws \CiviCRM_API3_Exception
    */
-  public static function callBatchMerge(CRM_Queue_TaskContext $ctx, $rgid, $gid, $mode = 'safe', $batchLimit, $isSelected, $criteria) {
-    CRM_Dedupe_Merger::batchMerge($rgid, $gid, $mode, $batchLimit, $isSelected, $criteria, TRUE, FALSE);
+  public static function callBatchMerge(CRM_Queue_TaskContext $ctx, $rgid, $gid, $mode = 'safe', $batchLimit, $isSelected, $criteria, $searchLimit) {
+    CRM_Dedupe_Merger::batchMerge($rgid, $gid, $mode, $batchLimit, $isSelected, $criteria, TRUE, FALSE, $searchLimit);
     return CRM_Queue_Task::TASK_SUCCESS;
   }
 
diff --git a/CRM/Core/BAO/PrevNextCache.php b/CRM/Core/BAO/PrevNextCache.php
index bcc8e650f8f0..20b9fcfe486b 100644
--- a/CRM/Core/BAO/PrevNextCache.php
+++ b/CRM/Core/BAO/PrevNextCache.php
@@ -429,7 +429,7 @@ public static function getCount($cacheKey, $join = NULL, $where = NULL, $op = "=
    * @throws \CiviCRM_API3_Exception
    */
   public static function refillCache($rgid, $gid, $criteria, $checkPermissions, $searchLimit = 0) {
-    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria, $checkPermissions);
+    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($rgid, $gid, $criteria, $checkPermissions, $searchLimit);
 
     // 1. Clear cache if any
     $sql = "DELETE FROM civicrm_prevnext_cache WHERE  cachekey LIKE %1";
diff --git a/CRM/Dedupe/Merger.php b/CRM/Dedupe/Merger.php
index 9e501f35f60c..a35ae67e792d 100644
--- a/CRM/Dedupe/Merger.php
+++ b/CRM/Dedupe/Merger.php
@@ -691,9 +691,17 @@ public static function retrieveFields($main, $other) {
    *  If not set explicitly this is calculated but it is preferred that it be set
    *  per comments on isSelected above.
    *
+   * @param int $searchLimit
+   *   Limit on number of contacts to search for duplicates for.
+   *   This means that if the limit is 1000 then only duplicates for the first 1000 contacts
+   *   matching criteria will be found and batchMerged (the number of merges could be less than or greater than 100)
+   *
    * @return array|bool
+   *
+   * @throws \CRM_Core_Exception
+   * @throws \CiviCRM_API3_Exception
    */
-  public static function batchMerge($rgid, $gid = NULL, $mode = 'safe', $batchLimit = 1, $isSelected = 2, $criteria = [], $checkPermissions = TRUE, $reloadCacheIfEmpty = NULL) {
+  public static function batchMerge($rgid, $gid = NULL, $mode = 'safe', $batchLimit = 1, $isSelected = 2, $criteria = [], $checkPermissions = TRUE, $reloadCacheIfEmpty = NULL, $searchLimit = 0) {
     $redirectForPerformance = ($batchLimit > 1) ? TRUE : FALSE;
 
     if (!isset($reloadCacheIfEmpty)) {
@@ -706,7 +714,7 @@ public static function batchMerge($rgid, $gid = NULL, $mode = 'safe', $batchLimi
     $dupePairs = self::getDuplicatePairs($rgid, $gid, $reloadCacheIfEmpty, $batchLimit, $isSelected, ($mode == 'aggressive'), $criteria, $checkPermissions);
 
     $cacheParams = [
-      'cache_key_string' => self::getMergeCacheKeyString($rgid, $gid, $criteria, $checkPermissions),
+      'cache_key_string' => self::getMergeCacheKeyString($rgid, $gid, $criteria, $checkPermissions, $searchLimit),
       // @todo stop passing these parameters in & instead calculate them in the merge function based
       // on the 'real' params like $isRespectExclusions $batchLimit and $isSelected.
       'join' => self::getJoinOnDedupeTable(),
@@ -1840,13 +1848,13 @@ public static function createMergeActivities($mainId, $otherId) {
    * @throws \CiviCRM_API3_Exception
    */
   public static function getDuplicatePairs($rule_group_id, $group_id, $reloadCacheIfEmpty, $batchLimit, $isSelected, $includeConflicts = TRUE, $criteria = [], $checkPermissions = TRUE, $searchLimit = 0) {
-    $dupePairs = self::getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, $includeConflicts, $criteria, $checkPermissions);
+    $dupePairs = self::getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, $includeConflicts, $criteria, $checkPermissions, $searchLimit);
     if (empty($dupePairs) && $reloadCacheIfEmpty) {
       // If we haven't found any dupes, probably cache is empty.
       // Try filling cache and give another try. We don't need to specify include conflicts here are there will not be any
       // until we have done some processing.
       CRM_Core_BAO_PrevNextCache::refillCache($rule_group_id, $group_id, $criteria, $checkPermissions, $searchLimit);
-      return self::getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, FALSE, $criteria, $checkPermissions);
+      return self::getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, FALSE, $criteria, $checkPermissions, $searchLimit);
     }
     return $dupePairs;
   }
@@ -1859,17 +1867,21 @@ public static function getDuplicatePairs($rule_group_id, $group_id, $reloadCache
    * @param array $criteria
    *   Additional criteria to narrow down the merge group.
    *   Currently we are only supporting the key 'contact' within it.
-   *
    * @param bool $checkPermissions
    *   Respect the users permissions.
+   * @param int $searchLimit
+   *   Number of contacts to seek dupes for (we need this because if
+   *   we change it the results won't be refreshed otherwise. Changing the limit
+   *   from 100 to 1000 SHOULD result in a new dedupe search).
    *
    * @return string
    */
-  public static function getMergeCacheKeyString($rule_group_id, $group_id, $criteria = [], $checkPermissions = TRUE) {
+  public static function getMergeCacheKeyString($rule_group_id, $group_id, $criteria, $checkPermissions, $searchLimit) {
     $contactType = CRM_Dedupe_BAO_RuleGroup::getContactTypeForRuleGroup($rule_group_id);
     $cacheKeyString = "merge_{$contactType}";
     $cacheKeyString .= $rule_group_id ? "_{$rule_group_id}" : '_0';
     $cacheKeyString .= $group_id ? "_{$group_id}" : '_0';
+    $cacheKeyString .= '_' . (int) $searchLimit;
     $cacheKeyString .= !empty($criteria) ? md5(serialize($criteria)) : '_0';
     if ($checkPermissions) {
       $contactID = CRM_Core_Session::getLoggedInContactID();
@@ -2487,12 +2499,13 @@ protected static function formatConflictArray($conflicts, $migrationInfo, $toKee
    * @param bool $includeConflicts
    * @param array $criteria
    * @param int $checkPermissions
+   * @param int $searchLimit
    *
    * @return array
    */
-  protected static function getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, $includeConflicts, $criteria, $checkPermissions) {
+  protected static function getCachedDuplicateMatches($rule_group_id, $group_id, $batchLimit, $isSelected, $includeConflicts, $criteria, $checkPermissions, $searchLimit = 0) {
     return CRM_Core_BAO_PrevNextCache::retrieve(
-      self::getMergeCacheKeyString($rule_group_id, $group_id, $criteria, $checkPermissions),
+      self::getMergeCacheKeyString($rule_group_id, $group_id, $criteria, $checkPermissions, $searchLimit),
       self::getJoinOnDedupeTable(),
       self::getWhereString($isSelected),
       0, $batchLimit,
diff --git a/api/v3/Dedupe.php b/api/v3/Dedupe.php
index 009920691840..58041ea3f948 100644
--- a/api/v3/Dedupe.php
+++ b/api/v3/Dedupe.php
@@ -107,7 +107,8 @@ function civicrm_api3_dedupe_getstatistics($params) {
     $params['rule_group_id'],
     CRM_Utils_Array::value('group_id', $params),
     CRM_Utils_Array::value('criteria', $params, []),
-    CRM_Utils_Array::value('check_permissions', $params, [])
+    !empty($params['check_permissions']),
+    CRM_Utils_Array::value('search_limit', $params, 0)
   ));
   return civicrm_api3_create_success($stats);
 }
@@ -135,6 +136,11 @@ function _civicrm_api3_dedupe_getstatistics_spec(&$params) {
     'title' => ts('Criteria'),
     'description' => ts('Dedupe search criteria, as parsable by v3 Contact.get api'),
   ];
+  $spec['search_limit'] = [
+    'title' => ts('Number of contacts to look for matches for.'),
+    'type' => CRM_Utils_Type::T_INT,
+    'api.default' => (int) Civi::settings()->get('dedupe_default_limit'),
+  ];
 
 }
 
diff --git a/api/v3/Job.php b/api/v3/Job.php
index 86cfa253d27f..4a4b0eca75f0 100644
--- a/api/v3/Job.php
+++ b/api/v3/Job.php
@@ -541,7 +541,7 @@ function civicrm_api3_job_process_batch_merge($params) {
   $gid = CRM_Utils_Array::value('gid', $params);
   $mode = CRM_Utils_Array::value('mode', $params, 'safe');
 
-  $result = CRM_Dedupe_Merger::batchMerge($rule_group_id, $gid, $mode, 1, 2, CRM_Utils_Array::value('criteria', $params, []), CRM_Utils_Array::value('check_permissions', $params));
+  $result = CRM_Dedupe_Merger::batchMerge($rule_group_id, $gid, $mode, 1, 2, CRM_Utils_Array::value('criteria', $params, []), CRM_Utils_Array::value('check_permissions', $params), NULL, $params['search_limit']);
 
   return civicrm_api3_create_success($result, $params);
 }
@@ -571,6 +571,12 @@ function _civicrm_api3_job_process_batch_merge_spec(&$params) {
     'description' => 'let the api decide which contact to retain and which to delete?',
     'type' => CRM_Utils_Type::T_BOOLEAN,
   ];
+  $params['search_limit'] = [
+    'title' => ts('Number of contacts to look for matches for.'),
+    'type' => CRM_Utils_Type::T_INT,
+    'api.default' => (int) Civi::settings()->get('dedupe_default_limit'),
+  ];
+
 }
 
 /**
diff --git a/tests/phpunit/CRM/Dedupe/MergerTest.php b/tests/phpunit/CRM/Dedupe/MergerTest.php
index a5e3c8c67a24..0798109eae5b 100644
--- a/tests/phpunit/CRM/Dedupe/MergerTest.php
+++ b/tests/phpunit/CRM/Dedupe/MergerTest.php
@@ -175,7 +175,7 @@ public function testBatchMergeSelectedDuplicates() {
 
     // Retrieve pairs from prev next cache table
     $select = ['pn.is_selected' => 'is_selected'];
-    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($dao->id, $this->_groupId);
+    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($dao->id, $this->_groupId, [], TRUE, 0);
     $pnDupePairs = CRM_Core_BAO_PrevNextCache::retrieve($cacheKeyString, NULL, NULL, 0, 0, $select);
     $this->assertEquals(count($foundDupes), count($pnDupePairs), 'Check number of dupe pairs in prev next cache.');
 
@@ -245,7 +245,7 @@ public function testBatchMergeAllDuplicates() {
 
     // Retrieve pairs from prev next cache table
     $select = ['pn.is_selected' => 'is_selected'];
-    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($dao->id, $this->_groupId);
+    $cacheKeyString = CRM_Dedupe_Merger::getMergeCacheKeyString($dao->id, $this->_groupId, [], TRUE, 0);
     $pnDupePairs = CRM_Core_BAO_PrevNextCache::retrieve($cacheKeyString, NULL, NULL, 0, 0, $select);
 
     $this->assertEquals(count($foundDupes), count($pnDupePairs), 'Check number of dupe pairs in prev next cache.');