diff --git a/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.controller.js b/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.controller.js
index b18de506e25..d66ae9aa25c 100644
--- a/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.controller.js
+++ b/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.controller.js
@@ -16,13 +16,41 @@ module.exports = angular.module('spinnaker.amazon.serverGroup.details.rollback.c
       $scope.allServerGroups = allServerGroups.sort((a, b) => b.name.localeCompare(a.name));
       $scope.verification = {};
 
+      var desired = serverGroup.capacity.desired;
+
+      function calcPercent(badInstances) {
+        return Math.floor((desired - badInstances) / desired * 100);
+      }
+
+      if (desired < 10) {
+        var healthyPercent = 100;
+      } else if (desired < 20) {
+        // accept 1 instance in an unknown state during rollback
+        healthyPercent = calcPercent(1);
+      } else if (desired <= 32) {
+        healthyPercent = calcPercent(2);
+      } else if (desired <= 64) {
+        healthyPercent = calcPercent(3);
+      } else if (desired <= 128) {
+        healthyPercent = calcPercent(4);
+      } else if (desired <= 256) {
+        healthyPercent = calcPercent(5);
+      } else if (desired > 256) {
+        healthyPercent = 98;
+      }
+
       $scope.command = {
         rollbackType: 'EXPLICIT',
         rollbackContext: {
-          rollbackServerGroupName: serverGroup.name
+          rollbackServerGroupName: serverGroup.name,
+          targetHealthyRollbackPercentage: healthyPercent
         }
       };
 
+      $scope.minHealthy = function(percent) {
+        return Math.ceil(desired * percent / 100);
+      };
+
       if (application && application.attributes) {
         if (application.attributes.platformHealthOnlyShowOverride && application.attributes.platformHealthOnly) {
           $scope.command.interestingHealthProviderNames = ['Amazon'];
diff --git a/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.html b/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.html
index b5172f06ce5..2d452bf543f 100644
--- a/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.html
+++ b/app/scripts/modules/amazon/src/serverGroup/details/rollback/rollbackServerGroup.html
@@ -30,7 +30,22 @@ <h3>Rollback {{serverGroup.name}}</h3>
         </div>
       </div>
 
-      <task-reason command="command"></task-reason>
+      <div class="row">
+        <task-reason command="command"></task-reason>
+      </div>
+
+      <div class="row">
+        <div class="col-sm-11 col-sm-offset-1">
+          Consider rollback successful when
+          <input type="number"
+                 min="0"
+                 max="100"
+                 ng-model="command.rollbackContext.targetHealthyRollbackPercentage"
+                 class="form-control input-sm inline-number"
+          />
+          percent of instances are healthy.
+        </div>
+      </div>
 
       <div class="row">
         <div class="col-sm-4 sm-label-right">
@@ -46,6 +61,10 @@ <h3>Rollback {{serverGroup.name}}</h3>
               <strong>max</strong>: {{ serverGroup.capacity.max }},
               <strong>desired</strong>: {{ serverGroup.capacity.desired }}
             ]<br/>(minimum capacity pinned at {{serverGroup.capacity.desired}} to prevent autoscaling down during rollback)
+              <div ng-if="command.rollbackContext.targetHealthyRollbackPercentage < 100">
+                (resize considered successful when at least {{minHealthy(command.rollbackContext.targetHealthyRollbackPercentage)}}
+                instances report healthy)
+              </div>
             </li>
             <li>Disable {{ serverGroup.name }}</li>
             <li>Restore minimum capacity of <em>{{ command.rollbackContext.restoreServerGroupName || 'previous server group' }}</em> [