Index: binaries/data/mods/public/gui/summary/counters.js
===================================================================
--- binaries/data/mods/public/gui/summary/counters.js
+++ binaries/data/mods/public/gui/summary/counters.js
@@ -334,6 +334,12 @@
 	return { "population": playerState.sequences.populationCount[index] };
 }
 
+function calculateIdleTime(playerState, index)
+{
+	print(playerState.sequences.idleTime[index]+"\n");
+	return { "idleTime": playerState.sequences.idleTime[index]/1000 };
+}
+
 function calculateMapExploration(playerState, index)
 {
 	return { "percent": playerState.sequences.percentMapExplored[index] };
@@ -360,7 +366,7 @@
 	if (type == "killDeath")
 		return calculateRatio(g_TeamHelperData[team].enemyUnitsKilled[index], g_TeamHelperData[team].unitsLost[index]);
 
-	if (type == "bribes" || type == "population")
+	if (type == "bribes" || type == "population" || type == "idleTime")
 		return summaryArraySum(getPlayerValuesPerTeam(team, index, type, counters, headings));
 
 	return { "percent": g_TeamHelperData[team][type][index] };
Index: binaries/data/mods/public/gui/summary/layout.js
===================================================================
--- binaries/data/mods/public/gui/summary/layout.js
+++ binaries/data/mods/public/gui/summary/layout.js
@@ -194,6 +194,7 @@
 			{ "identifier": "playername", "caption": translate("Player name"), "yStart": 26, "width": 200 },
 			{ "identifier": "killDeath", "caption": translate("Kill / Death ratio"), "yStart": 16, "width": 100, "format": "DECIMAL2" },
 			{ "identifier": "population", "caption": translate("Population"), "yStart": 16, "width": 100, "hideInSummary": true },
+			{ "identifier": "idleTime", "caption": translate("Idle time"), "yStart": 16, "width": 100, "hideInSummary": true, "format": "DURATION_SHORT"},
 			{ "identifier": "mapControlPeak", "caption": translate("Map control (peak)"), "yStart": 16, "width": 100, "format": "PERCENTAGE" },
 			{ "identifier": "mapControl", "caption": translate("Map control (finish)"), "yStart": 16, "width": 100, "format": "PERCENTAGE" },
 			{ "identifier": "mapExploration", "caption": translate("Map exploration"), "yStart": 16, "width": 100, "format": "PERCENTAGE" },
@@ -215,6 +216,7 @@
 		"counters": [
 			{ "width": 100, "fn": calculateKillDeathRatio, "verticalOffset": 12 },
 			{ "width": 100, "fn": calculatePopulationCount, "verticalOffset": 12, "hideInSummary": true },
+			{ "width": 100, "fn": calculateIdleTime, "verticalOffset": 12, "hideInSummary": true },
 			{ "width": 100, "fn": calculateMapPeakControl, "verticalOffset": 12 },
 			{ "width": 100, "fn": calculateMapFinalControl, "verticalOffset": 12 },
 			{ "width": 100, "fn": calculateMapExploration, "verticalOffset": 12 },
Index: binaries/data/mods/public/gui/summary/summary.js
===================================================================
--- binaries/data/mods/public/gui/summary/summary.js
+++ binaries/data/mods/public/gui/summary/summary.js
@@ -94,6 +94,11 @@
 		"caption": translate("Received"),
 		"postfix": ""
 	},
+	"idleTime": {
+		"color": g_TypeColors.red,
+		"caption": translate("Idle time"),
+		"postfix": "s"
+	},
 	"population": {
 		"color": g_TypeColors.red,
 		"caption": translate("Population"),
Index: binaries/data/mods/public/simulation/components/GuiInterface.js
===================================================================
--- binaries/data/mods/public/simulation/components/GuiInterface.js
+++ binaries/data/mods/public/simulation/components/GuiInterface.js
@@ -1875,6 +1875,20 @@
 	return cmpRangeManager.GetEntitiesByPlayer(player).some(unit => this.IdleUnitFilter(unit, data.idleClasses, data.excludeUnits).idle);
 };
 
+/**
+ * Count the number of idle units.
+ *
+ * @param data.idleClasses	Array of class names to include.
+ * @param data.excludeUnits	Array of units to exclude.
+ *
+ * Returns the number of idle units
+ */
+GuiInterface.prototype.CountIdleUnits = function(player, data)
+{
+	let cmpRangeManager = Engine.QueryInterface(SYSTEM_ENTITY, IID_RangeManager);
+	return cmpRangeManager.GetEntitiesByPlayer(player).filter(unit => this.IdleUnitFilter(unit, data.idleClasses, data.excludeUnits).idle).length;
+};
+
 /**
  * Whether to filter an idle unit
  *
Index: binaries/data/mods/public/simulation/components/StatisticsTracker.js
===================================================================
--- binaries/data/mods/public/simulation/components/StatisticsTracker.js
+++ binaries/data/mods/public/simulation/components/StatisticsTracker.js
@@ -24,6 +24,11 @@
  */
 StatisticsTracker.prototype.UpdateSequenceInterval = 30 * 1000;
 
+/**
+ * This number specifies the time in milliseconds between consecutive times the idle units should be counted.
+ */
+StatisticsTracker.prototype.UpdateIdleUnitsInterval = 1 * 1000;
+
 StatisticsTracker.prototype.Init = function()
 {
 	this.unitsClasses = this.template.UnitClasses._string.split(/\s+/);
@@ -87,9 +92,16 @@
 	this.successfulBribes = 0;
 	this.failedBribes = 0;
 
+	this.prevIdleUnits = 0;
+	this.idleTime = 0;
+
 	let cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
+	this.prevIdleUpdate = cmpTimer.GetTime();
 	this.updateTimer = cmpTimer.SetInterval(
 		this.entity, IID_StatisticsTracker, "UpdateSequences", 0, this.UpdateSequenceInterval);
+
+	this.idleUnitsTimer = cmpTimer.SetInterval(
+		this.entity, IID_StatisticsTracker, "UpdateIdleUnits", 0, this.UpdateIdleUnitsInterval);
 };
 
 StatisticsTracker.prototype.OnGlobalInitGame = function()
@@ -149,7 +161,8 @@
 		"peakPercentMapControlled": this.peakPercentMapControlled,
 		"teamPeakPercentMapControlled": this.teamPeakPercentMapControlled,
 		"successfulBribes": this.successfulBribes,
-		"failedBribes": this.failedBribes
+		"failedBribes": this.failedBribes,
+		"idleTime": this.idleTime
 	};
 };
 
@@ -522,6 +535,28 @@
 	this.teamPeakPercentMapControlled = Math.max(this.teamPeakPercentMapControlled, this.GetTeamPercentMapControlled());
 };
 
+StatisticsTracker.prototype.UpdateIdleUnits = function()
+{
+	let cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
+	let time = cmpTimer.GetTime();
+	let passed = time - this.prevIdleUpdate;
+	this.prevIdleUpdate = time;
+
+	let cmpPlayer = Engine.QueryInterface(this.entity, IID_Player);
+	let cmpGUIInterface = Engine.QueryInterface(SYSTEM_ENTITY, IID_GuiInterface);
+	let idleUnits = cmpGUIInterface.CountIdleUnits(cmpPlayer.GetPlayerID(), {
+		"idleClasses": ["FemaleCitizen", "Trader", "FishingBoat", "Citizen"],
+		"excludeUnits": []
+	});
+
+	let stayedIdle = Math.min(this.prevIdleUnits, idleUnits);
+	let changedIdle = Math.max(this.prevIdleUnits, idleUnits) - stayedIdle;
+
+	this.prevIdleUnits = idleUnits;
+	this.idleTime += passed * (stayedIdle + changedIdle / 2);
+	print(this.entity + ": " + this.idleTime + "\n");
+}
+
 /**
  * Adds the values of fromData to the end of the arrays of toData.
  * If toData misses the needed array, one will be created.