diff --git a/app/src/main/java/com/simplemobiletools/calendar/CalendarImpl.java b/app/src/main/java/com/simplemobiletools/calendar/CalendarImpl.java
index 30dc4cb5a..11a01d85c 100644
--- a/app/src/main/java/com/simplemobiletools/calendar/CalendarImpl.java
+++ b/app/src/main/java/com/simplemobiletools/calendar/CalendarImpl.java
@@ -76,8 +76,9 @@ public class CalendarImpl implements DBHelper.DBOperationsListener {
 
             isToday = isThisMonth && isToday(mTargetDate, value);
 
-            final String dayCode = Formatter.getDayCodeFromDateTime(curDay.withDayOfMonth(value));
-            final Day day = new Day(value, isThisMonth, isToday, dayCode, hasEvent(dayCode));
+            final DateTime newDay = curDay.withDayOfMonth(value);
+            final String dayCode = Formatter.getDayCodeFromDateTime(newDay);
+            final Day day = new Day(value, isThisMonth, isToday, dayCode, hasEvent(dayCode), newDay.getWeekOfWeekyear());
             days.add(day);
             value++;
         }
diff --git a/app/src/main/java/com/simplemobiletools/calendar/MyWidgetProvider.java b/app/src/main/java/com/simplemobiletools/calendar/MyWidgetProvider.java
index f296afad4..73b95ede9 100644
--- a/app/src/main/java/com/simplemobiletools/calendar/MyWidgetProvider.java
+++ b/app/src/main/java/com/simplemobiletools/calendar/MyWidgetProvider.java
@@ -129,8 +129,16 @@ public class MyWidgetProvider extends AppWidgetProvider implements Calendar {
     }
 
     public void updateDays(List<Day> days) {
-        final String packageName = mContext.getPackageName();
         final int len = days.size();
+        final String packageName = mContext.getPackageName();
+        mRemoteViews.setInt(R.id.week_num, "setTextColor", mWeakTextColor);
+
+        for (int i = 0; i < 6; i++) {
+            final int id = mRes.getIdentifier("week_num_" + i, "id", packageName);
+            mRemoteViews.setTextViewText(id, days.get(i * 7).getWeekOfYear() + ":");
+            mRemoteViews.setInt(id, "setTextColor", mWeakTextColor);
+        }
+
         for (int i = 0; i < len; i++) {
             final Day day = days.get(i);
             final int id = mRes.getIdentifier("day_" + i, "id", packageName);
diff --git a/app/src/main/java/com/simplemobiletools/calendar/activities/WidgetConfigureActivity.java b/app/src/main/java/com/simplemobiletools/calendar/activities/WidgetConfigureActivity.java
index f824ef324..cd0416e7a 100644
--- a/app/src/main/java/com/simplemobiletools/calendar/activities/WidgetConfigureActivity.java
+++ b/app/src/main/java/com/simplemobiletools/calendar/activities/WidgetConfigureActivity.java
@@ -184,6 +184,15 @@ public class WidgetConfigureActivity extends AppCompatActivity implements Calend
 
     private void updateDays() {
         final int len = mDays.size();
+        final TextView weekNum = (TextView) findViewById(R.id.week_num);
+        weekNum.setTextColor(mWeakTextColor);
+
+        for (int i = 0; i < 6; i++) {
+            final TextView weekIdTV = (TextView) findViewById(mRes.getIdentifier("week_num_" + i, "id", mPackageName));
+            weekIdTV.setText(mDays.get(i * 7).getWeekOfYear() + ":");
+            weekIdTV.setTextColor(mWeakTextColor);
+        }
+
         for (int i = 0; i < len; i++) {
             final Day day = mDays.get(i);
             final TextView dayTV = (TextView) findViewById(mRes.getIdentifier("day_" + i, "id", mPackageName));
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/fragments/MonthFragment.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/fragments/MonthFragment.kt
index d6eedae35..54a910a17 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/fragments/MonthFragment.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/fragments/MonthFragment.kt
@@ -14,6 +14,7 @@ import android.widget.*
 import com.simplemobiletools.calendar.*
 import com.simplemobiletools.calendar.activities.DayActivity
 import com.simplemobiletools.calendar.models.Day
+import kotlinx.android.synthetic.main.first_row.*
 import kotlinx.android.synthetic.main.month_fragment.view.*
 import kotlinx.android.synthetic.main.top_navigation.view.*
 import org.joda.time.DateTime
@@ -160,6 +161,13 @@ class MonthFragment : Fragment(), Calendar {
 
     private fun updateDays(days: List<Day>) {
         val len = days.size
+        week_num.setTextColor(mWeakTextColor)
+
+        for (i in 0..5) {
+            val weekIdTV = mHolder.findViewById(mRes.getIdentifier("week_num_" + i, "id", mPackageName)) as TextView
+            weekIdTV.text = "${days[i * 7].weekOfYear}:"
+            weekIdTV.setTextColor(mWeakTextColor)
+        }
 
         for (i in 0..len - 1) {
             val day = days[i]
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/models/Day.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/models/Day.kt
index c0a980f5f..3c028b8e2 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/models/Day.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/models/Day.kt
@@ -1,7 +1,7 @@
 package com.simplemobiletools.calendar.models
 
-class Day(val value: Int, val isThisMonth: Boolean, val isToday: Boolean, val code: String, val hasEvent: Boolean) {
+class Day(val value: Int, val isThisMonth: Boolean, val isToday: Boolean, val code: String, val hasEvent: Boolean, val weekOfYear: Int) {
     override fun toString(): String {
-        return "Day {value=$value, isThisMonth=$isThisMonth, itToday=$isToday, code=$code, hasEvent=$hasEvent}"
+        return "Day {value=$value, isThisMonth=$isThisMonth, itToday=$isToday, code=$code, hasEvent=$hasEvent, weekOfYear=$weekOfYear}"
     }
 }
diff --git a/app/src/main/res/layout/first_row.xml b/app/src/main/res/layout/first_row.xml
index 78b1655b6..9fd8507f1 100644
--- a/app/src/main/res/layout/first_row.xml
+++ b/app/src/main/res/layout/first_row.xml
@@ -6,6 +6,14 @@
     android:layout_weight="1"
     android:orientation="horizontal">
 
+    <TextView
+        android:id="@+id/week_num"
+        style="@style/DayView"
+        android:layout_width="0dp"
+        android:layout_height="match_parent"
+        android:layout_weight="1"
+        android:text="#"/>
+
     <TextView
         android:id="@+id/label_0"
         style="@style/DayView"
diff --git a/app/src/main/res/layout/month_fragment.xml b/app/src/main/res/layout/month_fragment.xml
index 28d9c5884..54c656290 100644
--- a/app/src/main/res/layout/month_fragment.xml
+++ b/app/src/main/res/layout/month_fragment.xml
@@ -27,6 +27,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_0"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_0"
                 style="@style/DayView"
@@ -83,6 +90,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_1"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_7"
                 style="@style/DayView"
@@ -139,6 +153,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_2"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_14"
                 style="@style/DayView"
@@ -195,6 +216,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_3"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_21"
                 style="@style/DayView"
@@ -251,6 +279,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_4"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_28"
                 style="@style/DayView"
@@ -307,6 +342,13 @@
             android:layout_weight="1"
             android:orientation="horizontal">
 
+            <TextView
+                android:id="@+id/week_num_5"
+                style="@style/DayView"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:layout_weight="1"/>
+
             <TextView
                 android:id="@+id/day_35"
                 style="@style/DayView"