diff --git a/doc/changelog.dox b/doc/changelog.dox
index 299a2e88e..7a5b9be6f 100644
--- a/doc/changelog.dox
+++ b/doc/changelog.dox
@@ -72,6 +72,8 @@ See also:
     @ref Platform::GlfwApplication::setCursor() and
     @ref Platform::EmscriptenApplication::setCursor() (see
     [mosra/magnum#383](https://github.com/mosra/magnum/pull/383))
+-   Added @ref Platform::GlfwApplication::setWindowSize() and
+    @ref Platform::Sdl2Application::setWindowSize()
 -   Window icon management using @ref Platform::Sdl2Application::setWindowIcon()
     and @ref Platform::GlfwApplication::setWindowIcon() (see
     [mosra/magnum#393](https://github.com/mosra/magnum/issues/393))
diff --git a/src/Magnum/Platform/GlfwApplication.cpp b/src/Magnum/Platform/GlfwApplication.cpp
index 9d7df72f0..cc9f53e45 100644
--- a/src/Magnum/Platform/GlfwApplication.cpp
+++ b/src/Magnum/Platform/GlfwApplication.cpp
@@ -647,6 +647,13 @@ Vector2i GlfwApplication::windowSize() const {
     return size;
 }
 
+void GlfwApplication::setWindowSize(const Vector2i& size) {
+    CORRADE_ASSERT(_window, "Platform::GlfwApplication::setWindowSize(): no window opened", );
+
+    const Vector2i newSize = _dpiScaling*size;
+    glfwSetWindowSize(_window, newSize.x(), newSize.y());
+}
+
 #if GLFW_VERSION_MAJOR*100 + GLFW_VERSION_MINOR >= 302
 void GlfwApplication::setMinWindowSize(const Vector2i& size) {
     CORRADE_ASSERT(_window, "Platform::GlfwApplication::setMinWindowSize(): no window opened", );
diff --git a/src/Magnum/Platform/GlfwApplication.h b/src/Magnum/Platform/GlfwApplication.h
index b8bada13b..39d5cfab0 100644
--- a/src/Magnum/Platform/GlfwApplication.h
+++ b/src/Magnum/Platform/GlfwApplication.h
@@ -355,6 +355,18 @@ class GlfwApplication {
          */
         Vector2i windowSize() const;
 
+        /**
+         * @brief Set window size
+         * @param size    The size, in screen coordinates
+         * @m_since_latest
+         *
+         * To make the sizing work independently of the display DPI, @p size is
+         * internally multiplied with @ref dpiScaling() before getting applied.
+         * Expects that a window is already created.
+         * @see @ref setMinWindowSize(), @ref setMaxWindowSize()
+         */
+        void setWindowSize(const Vector2i& size);
+
         #if GLFW_VERSION_MAJOR*100 + GLFW_VERSION_MINOR >= 302 || defined(DOXYGEN_GENERATING_OUTPUT)
         /**
          * @brief Set window minimum size
@@ -364,8 +376,9 @@ class GlfwApplication {
          * If a value is set to @cpp -1 @ce, it will disable/remove the
          * corresponding limit. To make the sizing work independently of the
          * display DPI, @p size is internally multiplied with @ref dpiScaling()
-         * before getting applied.
+         * before getting applied. Expects that a window is already created.
          * @note Supported since GLFW 3.2.
+         * @see @ref setMaxWindowSize(), @ref setWindowSize()
          */
         void setMinWindowSize(const Vector2i& size = {-1, -1});
 
@@ -377,8 +390,9 @@ class GlfwApplication {
          * If a value is set to @cpp -1 @ce, it will disable/remove the
          * corresponding limit. To make the sizing work independently of the
          * display DPI, @p size is internally multiplied with @ref dpiScaling()
-         * before getting applied.
+         * before getting applied. Expects that a window is already created.
          * @note Supported since GLFW 3.2.
+         * @see @ref setMinWindowSize(), @ref setMaxWindowSize()
          */
         void setMaxWindowSize(const Vector2i& size = {-1, -1});
         #endif
diff --git a/src/Magnum/Platform/Sdl2Application.cpp b/src/Magnum/Platform/Sdl2Application.cpp
index 00afd9e47..1f5ae7e24 100644
--- a/src/Magnum/Platform/Sdl2Application.cpp
+++ b/src/Magnum/Platform/Sdl2Application.cpp
@@ -639,6 +639,13 @@ Vector2i Sdl2Application::windowSize() const {
 }
 
 #ifndef CORRADE_TARGET_EMSCRIPTEN
+void Sdl2Application::setWindowSize(const Vector2i& size) {
+    CORRADE_ASSERT(_window, "Platform::Sdl2Application::setWindowSize(): no window opened", );
+
+    const Vector2i newSize = _dpiScaling*size;
+    SDL_SetWindowSize(_window, newSize.x(), newSize.y());
+}
+
 void Sdl2Application::setMinWindowSize(const Vector2i& size) {
     CORRADE_ASSERT(_window, "Platform::Sdl2Application::setMinWindowSize(): no window opened", );
 
diff --git a/src/Magnum/Platform/Sdl2Application.h b/src/Magnum/Platform/Sdl2Application.h
index 9bc616870..2dae1f491 100644
--- a/src/Magnum/Platform/Sdl2Application.h
+++ b/src/Magnum/Platform/Sdl2Application.h
@@ -637,6 +637,19 @@ class Sdl2Application {
         Vector2i windowSize() const;
 
         #if !defined(CORRADE_TARGET_EMSCRIPTEN) || defined(DOXYGEN_GENERATING_OUTPUT)
+        /**
+         * @brief Set window size
+         * @param size    The size, in screen coordinates
+         * @m_since_latest
+         *
+         * To make the sizing work independently of the display DPI, @p size is
+         * internally multiplied with @ref dpiScaling() before getting applied.
+         * Expects that a window is already created.
+         * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref setMinWindowSize(), @ref setMaxWindowSize()
+         */
+        void setWindowSize(const Vector2i& size);
+
         /**
          * @brief Set minimum window size
          * @param size    The minimum size, in screen coordinates
@@ -645,8 +658,10 @@ class Sdl2Application {
          * Note that, unlike in @ref GlfwApplication, SDL2 doesn't have a way
          * to disable/remove a size limit. To make the sizing work
          * independently of the display DPI, @p size is internally multiplied
-         * with @ref dpiScaling() before getting applied.
+         * with @ref dpiScaling() before getting applied. Expects that a window
+         * is already created.
          * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref setMaxWindowSize(), @ref setWindowSize()
          */
         void setMinWindowSize(const Vector2i& size);
 
@@ -658,8 +673,10 @@ class Sdl2Application {
          * Note that, unlike in @ref GlfwApplication, SDL2 doesn't have a way
          * to disable/remove a size limit. To make the sizing work
          * independently of the display DPI, @p size is internally multiplied
-         * with @ref dpiScaling() before getting applied.
+         * with @ref dpiScaling() before getting applied. Expects that a window
+         * is already created.
          * @note Not available in @ref CORRADE_TARGET_EMSCRIPTEN "Emscripten".
+         * @see @ref setMinWindowSize(), @ref setMaxWindowSize()
          */
         void setMaxWindowSize(const Vector2i& size);
         #endif
diff --git a/src/Magnum/Platform/Test/GlfwApplicationTest.cpp b/src/Magnum/Platform/Test/GlfwApplicationTest.cpp
index 9ea1ef775..4b56a1bf6 100644
--- a/src/Magnum/Platform/Test/GlfwApplicationTest.cpp
+++ b/src/Magnum/Platform/Test/GlfwApplicationTest.cpp
@@ -61,6 +61,9 @@ struct GlfwApplicationTest: Platform::Application {
         } else if(event.key() == KeyEvent::Key::T) {
             Debug{} << "setting window title";
             setWindowTitle("This is a UTF-8 Window Title™!");
+        } else if(event.key() == KeyEvent::Key::S) {
+            Debug{} << "setting window size, which should trigger a viewport event";
+            setWindowSize(Vector2i{300, 200});
         }
         #if GLFW_VERSION_MAJOR*100 + GLFW_VERSION_MINOR >= 302
         else if(event.key() == KeyEvent::Key::W) {
diff --git a/src/Magnum/Platform/Test/Sdl2ApplicationTest.cpp b/src/Magnum/Platform/Test/Sdl2ApplicationTest.cpp
index 9e4cbd2c6..accd868c8 100644
--- a/src/Magnum/Platform/Test/Sdl2ApplicationTest.cpp
+++ b/src/Magnum/Platform/Test/Sdl2ApplicationTest.cpp
@@ -87,7 +87,10 @@ struct Sdl2ApplicationTest: Platform::Application {
             setWindowTitle("This is a UTF-8 Window Title™!");
         }
         #ifndef CORRADE_TARGET_EMSCRIPTEN
-        else if(event.key() == KeyEvent::Key::W) {
+        else if(event.key() == KeyEvent::Key::S) {
+            Debug{} << "setting window size, which should trigger a viewport event";
+            setWindowSize(Vector2i{300, 200});
+        } else if(event.key() == KeyEvent::Key::W) {
             Debug{} << "setting max window size, which should trigger a viewport event";
             setMaxWindowSize(Vector2i{700, 500});
         }