diff --git a/lib/ContextModule.js b/lib/ContextModule.js
index ad0f98ce0..479d6a253 100644
--- a/lib/ContextModule.js
+++ b/lib/ContextModule.js
@@ -875,9 +875,10 @@ webpackEmptyAsyncContext.id = ${JSON.stringify(id)};`;
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		// base penalty
 		const initialSize = 160;
 
diff --git a/lib/DelegatedModule.js b/lib/DelegatedModule.js
index 49da48cf3..47717ab37 100644
--- a/lib/DelegatedModule.js
+++ b/lib/DelegatedModule.js
@@ -148,9 +148,10 @@ class DelegatedModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		return 42;
 	}
 
diff --git a/lib/DllModule.js b/lib/DllModule.js
index d816246e2..fc9771712 100644
--- a/lib/DllModule.js
+++ b/lib/DllModule.js
@@ -85,9 +85,10 @@ class DllModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		return 12;
 	}
 
diff --git a/lib/ExternalModule.js b/lib/ExternalModule.js
index 6aa0b167a..84dd08fdb 100644
--- a/lib/ExternalModule.js
+++ b/lib/ExternalModule.js
@@ -244,9 +244,10 @@ class ExternalModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		return 42;
 	}
 
diff --git a/lib/Generator.js b/lib/Generator.js
index eb0a6e2a7..361f14887 100644
--- a/lib/Generator.js
+++ b/lib/Generator.js
@@ -39,6 +39,16 @@ class Generator {
 		throw new Error("Generator.getTypes: must be overridden");
 	}
 
+	/**
+	 * @abstract
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		throw new Error("Generator.getSize: must be overridden");
+	}
+
 	/**
 	 * @abstract
 	 * @param {NormalModule} module module for which the code should be generated
@@ -67,6 +77,17 @@ class ByTypeGenerator extends Generator {
 		return this._types;
 	}
 
+	/**
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		const t = type || "javascript";
+		const generator = this.map[t];
+		return generator ? generator.getSize(module, t) : 0;
+	}
+
 	/**
 	 * @param {NormalModule} module module for which the code should be generated
 	 * @param {GenerateContext} generateContext context for generate
diff --git a/lib/JavascriptGenerator.js b/lib/JavascriptGenerator.js
index 16658c285..ca802cc91 100644
--- a/lib/JavascriptGenerator.js
+++ b/lib/JavascriptGenerator.js
@@ -58,6 +58,19 @@ class JavascriptGenerator extends Generator {
 		return TYPES;
 	}
 
+	/**
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		const originalSource = module.originalSource();
+		if (!originalSource) {
+			return 39;
+		}
+		return originalSource.size();
+	}
+
 	/**
 	 * @param {NormalModule} module module for which the code should be generated
 	 * @param {GenerateContext} generateContext context for generate
diff --git a/lib/JsonGenerator.js b/lib/JsonGenerator.js
index 26fceabf2..0cbc76182 100644
--- a/lib/JsonGenerator.js
+++ b/lib/JsonGenerator.js
@@ -35,6 +35,17 @@ class JsonGenerator extends Generator {
 		return TYPES;
 	}
 
+	/**
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		let data = module.buildInfo.jsonData;
+		if (!data) return 0;
+		return stringifySafe(data).length + 10;
+	}
+
 	/**
 	 * @param {NormalModule} module module for which the code should be generated
 	 * @param {GenerateContext} generateContext context for generate
diff --git a/lib/Module.js b/lib/Module.js
index 3b61f233e..77dd46812 100644
--- a/lib/Module.js
+++ b/lib/Module.js
@@ -557,9 +557,10 @@ class Module extends DependenciesBlock {
 
 	/**
 	 * @abstract
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		throw new Error("Module.size: Must be overriden");
 	}
 
diff --git a/lib/NormalModule.js b/lib/NormalModule.js
index c335d54ba..410bffa80 100644
--- a/lib/NormalModule.js
+++ b/lib/NormalModule.js
@@ -764,10 +764,11 @@ class NormalModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
-		return this._source ? this._source.size() : -1;
+	size(type) {
+		return this.generator.getSize(this, type);
 	}
 
 	/**
diff --git a/lib/RawModule.js b/lib/RawModule.js
index 767397343..ea4b505f6 100644
--- a/lib/RawModule.js
+++ b/lib/RawModule.js
@@ -39,9 +39,10 @@ class RawModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		return this.sourceStr.length;
 	}
 
diff --git a/lib/RuntimeModule.js b/lib/RuntimeModule.js
index 3bbcff834..009d26917 100644
--- a/lib/RuntimeModule.js
+++ b/lib/RuntimeModule.js
@@ -99,9 +99,10 @@ class RuntimeModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		return this.getGeneratedCode().length;
 	}
 
diff --git a/lib/optimize/ConcatenatedModule.js b/lib/optimize/ConcatenatedModule.js
index e58700a35..21c0f0d71 100644
--- a/lib/optimize/ConcatenatedModule.js
+++ b/lib/optimize/ConcatenatedModule.js
@@ -529,14 +529,15 @@ class ConcatenatedModule extends Module {
 	}
 
 	/**
+	 * @param {string=} type the source type for which the size should be estimated
 	 * @returns {number} the estimated size of the module
 	 */
-	size() {
+	size(type) {
 		// Guess size from embedded modules
 		return this._orderedConcatenationList.reduce((sum, info) => {
 			switch (info.type) {
 				case "concatenated":
-					return sum + info.module.size();
+					return sum + info.module.size(type);
 				case "external":
 					return sum + 5;
 			}
diff --git a/lib/wasm/WebAssemblyGenerator.js b/lib/wasm/WebAssemblyGenerator.js
index 99086f141..581bc2bea 100644
--- a/lib/wasm/WebAssemblyGenerator.js
+++ b/lib/wasm/WebAssemblyGenerator.js
@@ -384,6 +384,19 @@ class WebAssemblyGenerator extends Generator {
 		return TYPES;
 	}
 
+	/**
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		const originalSource = module.originalSource();
+		if (!originalSource) {
+			return 0;
+		}
+		return originalSource.size();
+	}
+
 	/**
 	 * @param {NormalModule} module module for which the code should be generated
 	 * @param {GenerateContext} generateContext context for generate
diff --git a/lib/wasm/WebAssemblyJavascriptGenerator.js b/lib/wasm/WebAssemblyJavascriptGenerator.js
index 008ddb1c0..18d6450d0 100644
--- a/lib/wasm/WebAssemblyJavascriptGenerator.js
+++ b/lib/wasm/WebAssemblyJavascriptGenerator.js
@@ -28,6 +28,15 @@ class WebAssemblyJavascriptGenerator extends Generator {
 		return TYPES;
 	}
 
+	/**
+	 * @param {NormalModule} module the module
+	 * @param {string=} type source type
+	 * @returns {number} estimate size of the module
+	 */
+	getSize(module, type) {
+		return 100 + module.dependencies.length * 5;
+	}
+
 	/**
 	 * @param {NormalModule} module module for which the code should be generated
 	 * @param {GenerateContext} generateContext context for generate