Index: binaries/data/mods/public/gui/common/tooltips.js
===================================================================
--- binaries/data/mods/public/gui/common/tooltips.js
+++ binaries/data/mods/public/gui/common/tooltips.js
@@ -380,6 +380,30 @@
 	});
 }
 
+function getBuildTimeTooltip(entState)
+{
+	if (!entState.foundation.numBuilders)
+		return sprintf(translatePlural(
+			"Add a worker to finish the construction in %(second)s second.",
+			"Add a worker to finish the construction in %(second)s seconds.",
+			Math.round(entState.buildTime.timeRemainingNew)),
+		{
+			"second": Math.round(entState.buildTime.timeRemainingNew)
+		});
+
+	return sprintf(translate("%(label)s %(details)s"), {
+			"label": headerFont(translate("Number of builders:")),
+			"details": entState.foundation.numBuilders
+		}) + '\n' +
+		sprintf(translatePlural(
+			"Add another worker to speed up the construction by %(second)s second.",
+			"Add another worker to speed up the construction by %(second)s seconds.",
+			Math.round(entState.buildTime.timeRemaining - entState.buildTime.timeRemainingNew)),
+		{
+			"second": Math.round(entState.buildTime.timeRemaining - entState.buildTime.timeRemainingNew)
+		});
+}
+
 /**
  * Multiplies the costs for a template by a given batch size.
  */
Index: binaries/data/mods/public/gui/session/selection_details.js
===================================================================
--- binaries/data/mods/public/gui/session/selection_details.js
+++ binaries/data/mods/public/gui/session/selection_details.js
@@ -112,15 +112,8 @@
 		healthSize.rright = 100*Math.max(0, Math.min(1, entState.hitpoints / entState.maxHitpoints));
 		unitHealthBar.size = healthSize;
 
-		if (entState.foundation && entState.visibility == "visible" && entState.foundation.numBuilders !== 0 && entState.buildTime)
-			Engine.GetGUIObjectByName("health").tooltip = sprintf(
-				translatePlural(
-					"This foundation will be completed in %(seconds)s second.",
-					"This foundation will be completed in %(seconds)s seconds.",
-					Math.ceil(entState.buildTime.timeRemaining)),
-				{
-					"seconds": Math.ceil(entState.buildTime.timeRemaining)
-				});
+		if (entState.foundation && entState.visibility == "visible")
+			Engine.GetGUIObjectByName("health").tooltip = getBuildTimeTooltip(entState);
 		else
 			Engine.GetGUIObjectByName("health").tooltip = "";
 
@@ -253,18 +246,11 @@
 		Engine.GetGUIObjectByName("resourceCarryingIcon").hidden = false;
 		Engine.GetGUIObjectByName("resourceCarryingText").hidden = false;
 		Engine.GetGUIObjectByName("resourceCarryingIcon").sprite = "stretched:session/icons/repair.png";
-		Engine.GetGUIObjectByName("resourceCarryingText").caption = entState.foundation.numBuilders + "    ";
-		if (entState.foundation.numBuilders !== 0 && entState.buildTime)
-			Engine.GetGUIObjectByName("resourceCarryingIcon").tooltip = sprintf(
-				translatePlural(
-					"Number of builders.\nTasking another to this foundation would speed construction up by %(speedup)s second.",
-					"Number of builders.\nTasking another to this foundation would speed construction up by %(speedup)s seconds.",
-					Math.ceil(entState.buildTime.timeSpeedup)),
-				{
-					"speedup": Math.ceil(entState.buildTime.timeSpeedup)
-				});
+		Engine.GetGUIObjectByName("resourceCarryingIcon").tooltip = getBuildTimeTooltip(entState);
+		if (entState.foundation.numBuilders)
+			Engine.GetGUIObjectByName("resourceCarryingText").caption = durationToString(entState.buildTime.timeRemaining * 1000) + "    ";
 		else
-			Engine.GetGUIObjectByName("resourceCarryingIcon").tooltip = translate("Number of builders.");
+			Engine.GetGUIObjectByName("resourceCarryingText").caption = "";
 	}
 	else if (entState.repairable && entState.repairable.numBuilders > 0 && entState.visibility == "visible")
 	{
Index: binaries/data/mods/public/simulation/components/Foundation.js
===================================================================
--- binaries/data/mods/public/simulation/components/Foundation.js
+++ binaries/data/mods/public/simulation/components/Foundation.js
@@ -173,7 +173,7 @@
 	let rateNew = (this.totalBuilderRate + 1) * this.CalculateBuildMultiplier(this.GetNumBuilders() + 1);
 	return {
 		"timeRemaining": timeLeft / rate,
-		"timeSpeedup": timeLeft / rate - timeLeft / rateNew
+		"timeRemainingNew": timeLeft / rateNew
 	};
 };
 
Index: binaries/data/mods/public/simulation/components/tests/test_Foundation.js
===================================================================
--- binaries/data/mods/public/simulation/components/tests/test_Foundation.js
+++ binaries/data/mods/public/simulation/components/tests/test_Foundation.js
@@ -147,7 +147,7 @@
 	// Foundation starts with 1 hp, so there's 50 * 99/100 = 49.5 seconds left.
 	TS_ASSERT_UNEVAL_EQUALS(cmpFoundation.GetBuildTime(), {
 		'timeRemaining': 49.5,
-		'timeSpeedup': 49.5 - 49.5 / (2 * twoBuilderMultiplier)
+		'timeRemainingNew': 49.5 / (2 * twoBuilderMultiplier)
 	});
 	cmpFoundation.AddBuilder(11);
 	TS_ASSERT_EQUALS(cmpFoundation.GetNumBuilders(), 2);
@@ -155,7 +155,7 @@
 	TS_ASSERT_EQUALS(cmpFoundation.totalBuilderRate, 2);
 	TS_ASSERT_UNEVAL_EQUALS(cmpFoundation.GetBuildTime(), {
 		'timeRemaining': 49.5 / (2 * twoBuilderMultiplier),
-		'timeSpeedup': 49.5 / (2 * twoBuilderMultiplier) - 49.5 / (3 * threeBuilderMultiplier)
+		'timeRemainingNew': 49.5 / (3 * threeBuilderMultiplier)
 	});
 	cmpFoundation.AddBuilder(11);
 	TS_ASSERT_EQUALS(cmpFoundation.GetNumBuilders(), 2);