diff --git a/CHANGELOG b/CHANGELOG
index ec542f58f27d1cdead909169324600df498a005b..df8dec7bddebe70a76b1d76afcf555861af5fdf7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -3,6 +3,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 v 8.12.0 (unreleased)
   - Add two-factor recovery endpoint to internal API !5510
   - Change merge_error column from string to text type
+  - Reduce contributions calendar data payload (ClemMakesApps)
   - Add `web_url` field to issue, merge request, and snippet API objects (Ben Boeckel)
   - Set path for all JavaScript cookies to honor GitLab's subdirectory setting !5627 (Mike Greiling)
   - Add hover color to emoji icon (ClemMakesApps)
diff --git a/app/assets/javascripts/lib/utils/datetime_utility.js b/app/assets/javascripts/lib/utils/datetime_utility.js
index 10afa7e432985da0f7eeb3d721e77161ec98b3bd..d4d5927d3b03e7abfed017f1bdb941210f7f2d24 100644
--- a/app/assets/javascripts/lib/utils/datetime_utility.js
+++ b/app/assets/javascripts/lib/utils/datetime_utility.js
@@ -67,6 +67,14 @@
       $.timeago.settings.strings = tmpLocale;
     };
 
+    w.gl.utils.getDayDifference = function(a, b) {
+      var millisecondsPerDay = 1000 * 60 * 60 * 24;
+      var date1 = Date.UTC(a.getFullYear(), a.getMonth(), a.getDate());
+      var date2 = Date.UTC(b.getFullYear(), b.getMonth(), b.getDate());
+
+      return Math.floor((date2 - date1) / millisecondsPerDay);
+    }
+
   })(window);
 
 }).call(this);
diff --git a/app/assets/javascripts/users/calendar.js b/app/assets/javascripts/users/calendar.js
index 8b3dbf5f5ae1f096a9dde213887ed708a12f686d..74ecf4f4cf90112908c64c0ecb559001e5bf7e51 100644
--- a/app/assets/javascripts/users/calendar.js
+++ b/app/assets/javascripts/users/calendar.js
@@ -3,7 +3,6 @@
 
   this.Calendar = (function() {
     function Calendar(timestamps, calendar_activities_path) {
-      var group, i;
       this.calendar_activities_path = calendar_activities_path;
       this.clickDay = bind(this.clickDay, this);
       this.currentSelectedDate = '';
@@ -13,26 +12,36 @@
       this.monthNames = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
       this.months = [];
       this.timestampsTmp = [];
-      i = 0;
-      group = 0;
-      _.each(timestamps, (function(_this) {
-        return function(count, date) {
-          var day, innerArray, newDate;
-          newDate = new Date(parseInt(date) * 1000);
-          day = newDate.getDay();
-          if ((day === 0 && i !== 0) || i === 0) {
-            _this.timestampsTmp.push([]);
-            group++;
-          }
-          innerArray = _this.timestampsTmp[group - 1];
-          innerArray.push({
-            count: count,
-            date: newDate,
-            day: day
-          });
-          return i++;
-        };
-      })(this));
+      var group = 0;
+
+      var today = new Date()
+      today.setHours(0, 0, 0, 0, 0);
+
+      var oneYearAgo = new Date(today);
+      oneYearAgo.setFullYear(today.getFullYear() - 1);
+
+      var days = gl.utils.getDayDifference(oneYearAgo, today);
+
+      for(var i = 0; i <= days; i++) {
+        var date = new Date(oneYearAgo);
+        date.setDate(date.getDate() + i);
+
+        var day = date.getDay();
+        var count = timestamps[date.getTime() * 0.001];
+
+        if ((day === 0 && i !== 0) || i === 0) {
+          this.timestampsTmp.push([]);
+          group++;
+        }
+
+        var innerArray = this.timestampsTmp[group - 1];
+        innerArray.push({
+          count: count || 0,
+          date: date,
+          day: day
+        });
+      }
+
       this.colorKey = this.initColorKey();
       this.color = this.initColor();
       this.renderSvg(group);
diff --git a/lib/gitlab/contributions_calendar.rb b/lib/gitlab/contributions_calendar.rb
index 9dc2602867e07da8731da1eedb2cb31796a03596..bd681f03173a41b71c0b552543371a91e8828cad 100644
--- a/lib/gitlab/contributions_calendar.rb
+++ b/lib/gitlab/contributions_calendar.rb
@@ -23,7 +23,6 @@ module Gitlab
 
       dates.each do |date|
         date_id = date.to_time.to_i.to_s
-        @timestamps[date_id] = 0
         day_events = events.find { |day_events| day_events["date"] == date }
 
         if day_events
diff --git a/spec/javascripts/datetime_utility_spec.js.coffee b/spec/javascripts/datetime_utility_spec.js.coffee
index 6b9617341fe7b34dc86fe374ebfa2ccb9bea4ee6..8bd113e7d860ff679d7deeaa6b4527779ab6e001 100644
--- a/spec/javascripts/datetime_utility_spec.js.coffee
+++ b/spec/javascripts/datetime_utility_spec.js.coffee
@@ -29,3 +29,22 @@ describe 'Date time utils', ->
     it 'should return Saturday', ->
       day = gl.utils.getDayName(new Date('07/23/2016'))
       expect(day).toBe('Saturday')
+
+  describe 'get day difference', ->
+    it 'should return 7', ->
+      firstDay = new Date('07/01/2016')
+      secondDay = new Date('07/08/2016')
+      difference = gl.utils.getDayDifference(firstDay, secondDay)
+      expect(difference).toBe(7)
+
+    it 'should return 31', ->
+      firstDay = new Date('07/01/2016')
+      secondDay = new Date('08/01/2016')
+      difference = gl.utils.getDayDifference(firstDay, secondDay)
+      expect(difference).toBe(31)
+
+    it 'should return 365', ->
+      firstDay = new Date('07/02/2015')
+      secondDay = new Date('07/01/2016')
+      difference = gl.utils.getDayDifference(firstDay, secondDay)
+      expect(difference).toBe(365)
\ No newline at end of file