diff --git a/MultimediaViewer.php b/MultimediaViewer.php
index ad4609258..2e668f9eb 100644
--- a/MultimediaViewer.php
+++ b/MultimediaViewer.php
@@ -45,6 +45,16 @@ if ( !isset( $wgMediaViewerAttributionLoggingSamplingFactor ) ) {
 	$wgMediaViewerAttributionLoggingSamplingFactor = false;
 }
 
+if ( !isset( $wgMediaViewerDimensionLoggingSamplingFactor ) ) {
+	/**
+	 * If set, records whether image dimension data was available. A value of 1000 means there will be an
+	 * 1:1000 chance to log the dimension event.
+	 * False if unset.
+	 * @var int|bool
+	 */
+	$wgMediaViewerDimensionLoggingSamplingFactor = false;
+}
+
 if ( !isset( $wgMediaViewerActionLoggingSamplingFactorMap ) ) {
 	/**
 	 * If set, records user actions via EventLogging and applies a sampling factor according to the map. A "default" key in the map must be set.
@@ -813,6 +823,7 @@ $wgResourceModules += array(
 			'mmv.provider',
 			'mmv.routing',
 			'mmv.logging.DurationLogger',
+			'mmv.logging.DimensionLogger',
 			'jquery.fullscreen',
 			'jquery.hidpi',
 			'jquery.scrollTo',
@@ -902,6 +913,19 @@ $wgResourceModules += array(
 		),
 	),
 
+	'mmv.logging.DimensionLogger' => $wgMediaViewerResourceTemplate + array(
+		'scripts' => array(
+			'mmv/logging/mmv.logging.DimensionLogger.js',
+		),
+
+		'dependencies' => array(
+			'mmv.base',
+			'mmv.logging.Logger',
+			'oojs',
+			'jquery.hidpi',
+		),
+	),
+
 	'mmv.head' => $wgMediaViewerResourceTemplate + array(
 		'scripts' => array(
 			'mmv/mmv.head.js',
@@ -936,10 +960,13 @@ $wgExtensionFunctions[] = function () {
 		$wgEventLoggingSchemas[ 'MultimediaViewerNetworkPerformance' ] = 7917896;
 		$wgEventLoggingSchemas[ 'MultimediaViewerDuration' ] = 8572641;
 		$wgEventLoggingSchemas[ 'MultimediaViewerAttribution' ] = 9758179;
+		$wgEventLoggingSchemas[ 'MultimediaViewerDimensions' ] = 10014238;
 
 		$wgResourceModules['mmv.logging.ActionLogger']['dependencies'][] = 'ext.eventLogging';
 		$wgResourceModules['mmv.logging.Performance']['dependencies'][] = 'ext.eventLogging';
 		$wgResourceModules['mmv.logging.DurationLogger']['dependencies'][] = 'ext.eventLogging';
+		$wgResourceModules['mmv.logging.AttributionLogger']['dependencies'][] = 'ext.eventLogging';
+		$wgResourceModules['mmv.logging.DimensionLogger']['dependencies'][] = 'ext.eventLogging';
 	}
 };
 
diff --git a/MultimediaViewerHooks.php b/MultimediaViewerHooks.php
index 2b208c6a7..f23cde3e3 100644
--- a/MultimediaViewerHooks.php
+++ b/MultimediaViewerHooks.php
@@ -139,8 +139,9 @@ class MultimediaViewerHooks {
 	 * @return bool
 	 */
 	public static function resourceLoaderGetConfigVars( &$vars ) {
-		global $wgAPIPropModules, $wgMediaViewerActionLoggingSamplingFactorMap, $wgNetworkPerformanceSamplingFactor, $wgMediaViewerDurationLoggingSamplingFactor,
-			$wgMediaViewerAttributionLoggingSamplingFactor, $wgMediaViewerIsInBeta, $wgMediaViewerUseThumbnailGuessing;
+		global $wgMediaViewerActionLoggingSamplingFactorMap, $wgNetworkPerformanceSamplingFactor,
+		       $wgMediaViewerDurationLoggingSamplingFactor, $wgMediaViewerAttributionLoggingSamplingFactor,
+		       $wgMediaViewerDimensionLoggingSamplingFactor, $wgMediaViewerIsInBeta, $wgMediaViewerUseThumbnailGuessing;
 		$vars['wgMultimediaViewer'] = array(
 			'infoLink' => self::$infoLink,
 			'discussionLink' => self::$discussionLink,
@@ -150,6 +151,7 @@ class MultimediaViewerHooks {
 			'networkPerformanceSamplingFactor' => $wgNetworkPerformanceSamplingFactor,
 			'actionLoggingSamplingFactorMap' => $wgMediaViewerActionLoggingSamplingFactorMap,
 			'attributionSamplingFactor' => $wgMediaViewerAttributionLoggingSamplingFactor,
+			'dimensionSamplingFactor' => $wgMediaViewerDimensionLoggingSamplingFactor,
 			'tooltipDelay' => 1000,
 		);
 		$vars['wgMediaViewer'] = true;
@@ -192,6 +194,8 @@ class MultimediaViewerHooks {
 				'tests/qunit/mmv/logging/mmv.logging.DurationLogger.test.js',
 				'tests/qunit/mmv/logging/mmv.logging.Performance.test.js',
 				'tests/qunit/mmv/logging/mmv.logging.ActionLogger.test.js',
+				'tests/qunit/mmv/logging/mmv.logging.AttributionLogger.test.js',
+				'tests/qunit/mmv/logging/mmv.logging.DimensionLogger.test.js',
 				'tests/qunit/mmv/model/mmv.model.test.js',
 				'tests/qunit/mmv/model/mmv.model.IwTitle.test.js',
 				'tests/qunit/mmv/model/mmv.model.TaskQueue.test.js',
diff --git a/resources/mmv/logging/mmv.logging.AttributionLogger.js b/resources/mmv/logging/mmv.logging.AttributionLogger.js
index 4c0ac0dd5..9519a4819 100644
--- a/resources/mmv/logging/mmv.logging.AttributionLogger.js
+++ b/resources/mmv/logging/mmv.logging.AttributionLogger.js
@@ -63,5 +63,6 @@
 		this.log( data );
 	};
 
+	mw.mmv.logging.AttributionLogger = AttributionLogger;
 	mw.mmv.attributionLogger = new AttributionLogger();
 }( mediaWiki, jQuery, OO ) );
\ No newline at end of file
diff --git a/resources/mmv/logging/mmv.logging.DimensionLogger.js b/resources/mmv/logging/mmv.logging.DimensionLogger.js
new file mode 100644
index 000000000..22a58d058
--- /dev/null
+++ b/resources/mmv/logging/mmv.logging.DimensionLogger.js
@@ -0,0 +1,76 @@
+/*
+ * This file is part of the MediaWiki extension MultimediaViewer.
+ *
+ * MultimediaViewer is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * MultimediaViewer is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with MultimediaViewer.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+( function ( mw, $, oo ) {
+	var DL;
+
+	/**
+	 * Writes EventLogging entries for size measurements related to thumbnail size selection
+	 * (bucket size vs. display size).
+	 * @class mw.mmv.logging.DimensionLogger
+	 * @extends mw.mmv.logging.Logger
+	 * @constructor
+	 */
+	function DimensionLogger() {}
+
+	oo.inheritClass( DimensionLogger, mw.mmv.logging.Logger );
+
+	DL = DimensionLogger.prototype;
+
+	/**
+	 * @override
+	 * @inheritdoc
+	 */
+	DL.samplingFactor = mw.config.get( 'wgMultimediaViewer' ).dimensionSamplingFactor;
+
+	/**
+	 * @override
+	 * @inheritdoc
+	 */
+	DL.schema = 'MultimediaViewerDimensions';
+
+	/**
+	 * Logs dimension data.
+	 * @param {mw.mmv.model.ThumbnailWidth} imageWidths widths of the imagethat will be displayed
+	 * @param {{width: Number, height: Number}} canvasDimensions canvas width and height in CSS pixels
+	 * @param {string} context reason for requesting the image, one of 'show', 'resize', 'preload'
+	 */
+	DL.logDimensions = function ( imageWidths, canvasDimensions, context ) {
+		var data;
+
+		data = {
+			screenWidth: screen.width,
+			screenHeight: screen.height,
+			viewportWidth: $( window).width(),
+			viewportHeight: $( window).height(),
+			canvasWidth: canvasDimensions.width,
+			canvasHeight: canvasDimensions.height,
+			devicePixelRatio: $.devicePixelRatio(),
+			imgWidth: imageWidths.cssWidth,
+			imageAspectRatio: imageWidths.cssWidth / imageWidths.cssHeight,
+			thumbWidth: imageWidths.real,
+			context: context,
+			samplingFactor: this.samplingFactor
+		};
+		mw.log( 'mw.mmw.logger.DimensionLogger', data );
+
+		this.log( data );
+	};
+
+	mw.mmv.logging.DimensionLogger = DimensionLogger;
+	mw.mmv.dimensionLogger = new DimensionLogger();
+}( mediaWiki, jQuery, OO ) );
\ No newline at end of file
diff --git a/resources/mmv/mmv.js b/resources/mmv/mmv.js
index 37d7d090f..46d440c23 100644
--- a/resources/mmv/mmv.js
+++ b/resources/mmv/mmv.js
@@ -179,14 +179,18 @@
 	 * @param {mw.mmv.LightboxInterface} ui lightbox that got resized
 	 */
 	MMVP.resize = function ( ui ) {
-		var viewer = this,
-			image = this.thumbs[ this.currentIndex ].image,
-			imageWidths;
+		var imageWidths, canvasDimensions,
+			viewer = this,
+			image = this.thumbs[ this.currentIndex ].image;
 
 		this.preloadThumbnails();
 
 		if ( image ) {
 			imageWidths = ui.canvas.getCurrentImageWidths();
+			canvasDimensions = ui.canvas.getDimensions();
+
+			mw.mmv.dimensionLogger.logDimensions( imageWidths, canvasDimensions, 'resize' );
+
 			this.fetchThumbnailForLightboxImage(
 				image, imageWidths.real
 			).then( function( thumbnail, image ) {
@@ -229,6 +233,7 @@
 	 */
 	MMVP.loadImage = function ( image, initialImage ) {
 		var imageWidths,
+			canvasDimensions,
 			imagePromise,
 			metadataPromise,
 			start,
@@ -259,10 +264,11 @@
 		// this.preloadFullscreenThumbnail( image ); // disabled - #474
 
 		imageWidths = this.ui.canvas.getCurrentImageWidths();
-
+		canvasDimensions = this.ui.canvas.getDimensions();
 
 		start = $.now();
 
+		mw.mmv.dimensionLogger.logDimensions( imageWidths, canvasDimensions, 'show' );
 		imagePromise = this.fetchThumbnailForLightboxImage( image, imageWidths.real );
 
 		this.resetBlurredThumbnailStates();
@@ -614,16 +620,20 @@
 
 		this.thumbnailPreloadQueue = this.pushLightboxImagesIntoQueue( function( lightboxImage ) {
 			return function() {
+				var imageWidths, canvasDimensions;
+
 				// viewer.ui.canvas.getLightboxImageWidths needs the viewer to be open
 				// because it needs to read the size of visible elements
 				if ( !viewer.isOpen ) {
 					return;
 				}
 
-				return viewer.fetchThumbnailForLightboxImage(
-					lightboxImage,
-					viewer.ui.canvas.getLightboxImageWidths( lightboxImage ).real
-				);
+				imageWidths = viewer.ui.canvas.getLightboxImageWidths( lightboxImage );
+				canvasDimensions = viewer.ui.canvas.getDimensions();
+
+				mw.mmv.dimensionLogger.logDimensions( imageWidths, canvasDimensions, 'preload' );
+
+				return viewer.fetchThumbnailForLightboxImage( lightboxImage, imageWidths.real );
 			};
 		} );
 
@@ -634,10 +644,11 @@
 	 * Preload the fullscreen size of the current image.
 	 */
 	MMVP.preloadFullscreenThumbnail = function( image ) {
-		this.fetchThumbnailForLightboxImage(
-			image,
-			this.ui.canvas.getLightboxImageWidthsForFullscreen( image ).real
-		);
+		var imageWidths = this.ui.canvas.getLightboxImageWidthsForFullscreen( image),
+			canvasDimensions = this.ui.canvas.getDimensions( true );
+
+		mw.mmv.dimensionLogger.logDimensions( imageWidths, canvasDimensions, 'preload' );
+		this.fetchThumbnailForLightboxImage( image, imageWidths.real );
 	};
 
 	/**
@@ -716,7 +727,7 @@
 			thumbnailPromise = this.guessedThumbnailInfoProvider.get(
 				fileTitle, sampleUrl, width, originalWidth, originalHeight
 			).then( null, function () { // catch rejection, use fallback
-					return viewer.thumbnailInfoProvider.get( fileTitle, width );
+				return viewer.thumbnailInfoProvider.get( fileTitle, width );
 			} );
 		} else {
 			thumbnailPromise = this.thumbnailInfoProvider.get( fileTitle, width );
diff --git a/resources/mmv/ui/mmv.ui.canvas.js b/resources/mmv/ui/mmv.ui.canvas.js
index 321da9bd4..a01247527 100644
--- a/resources/mmv/ui/mmv.ui.canvas.js
+++ b/resources/mmv/ui/mmv.ui.canvas.js
@@ -339,13 +339,13 @@
 	};
 
 	/**
-	 * Gets the widths for a given lightbox image.
-	 * @param {mw.mmv.LightboxImage} image
-	 * @returns {mw.mmv.model.ThumbnailWidth}
+	 * Returns width and height of the canvas area (i.e. the space available for the image).
+	 * @param {boolean} forFullscreen if true, return size in fullscreen mode; otherwise, return current size
+	 *  (which might still be fullscreen mode).
+	 * @return {{width: Number, height: Number}} width and height in CSS pixels
 	 */
-	C.getLightboxImageWidths = function ( image ) {
-		var thumb = image.thumbnail,
-			$window = $( window ),
+	C.getDimensions = function ( forFullscreen ) {
+		var $window = $( window ),
 			$aboveFold = $( '.mw-mmv-above-fold' ),
 			isFullscreened = !!$aboveFold.closest( '.jq-fullscreened' ).length,
 			// Don't rely on this.$imageWrapper's sizing because it's fragile.
@@ -354,8 +354,30 @@
 			availableWidth = $window.width(),
 			availableHeight =  $window.height() - ( isFullscreened ? 0 : $aboveFold.height() );
 
+		if ( forFullscreen ) {
+			return {
+				width: screen.width,
+				height: screen.height
+			};
+		} else {
+			return {
+				width: availableWidth,
+				height: availableHeight
+			};
+		}
+	};
+
+	/**
+	 * Gets the widths for a given lightbox image.
+	 * @param {mw.mmv.LightboxImage} image
+	 * @returns {mw.mmv.model.ThumbnailWidth}
+	 */
+	C.getLightboxImageWidths = function ( image ) {
+		var thumb = image.thumbnail,
+			canvasDimensions = this.getDimensions();
+
 		return this.thumbnailWidthCalculator.calculateWidths(
-			availableWidth, availableHeight, thumb.width, thumb.height );
+			canvasDimensions.width, canvasDimensions.height, thumb.width, thumb.height );
 	};
 
 	/**
@@ -366,10 +388,11 @@
 	 * @returns {mw.mmv.model.ThumbnailWidth}
 	 */
 	C.getLightboxImageWidthsForFullscreen = function ( image ) {
-		var thumb = image.thumbnail;
+		var thumb = image.thumbnail,
+			canvasDimensions = this.getDimensions( true );
 
 		return this.thumbnailWidthCalculator.calculateWidths(
-			screen.width, screen.height, thumb.width, thumb.height );
+			canvasDimensions.width, canvasDimensions.height, thumb.width, thumb.height );
 	};
 
 	/**
diff --git a/tests/qunit/mmv/logging/mmv.logging.AttributionLogger.test.js b/tests/qunit/mmv/logging/mmv.logging.AttributionLogger.test.js
new file mode 100644
index 000000000..cf5107803
--- /dev/null
+++ b/tests/qunit/mmv/logging/mmv.logging.AttributionLogger.test.js
@@ -0,0 +1,22 @@
+( function ( mw, $ ) {
+	QUnit.module( 'mmv.logging.AttributionLogger', QUnit.newMwEnvironment() );
+
+	QUnit.test( 'log()', 2, function ( assert ) {
+		var fakeEventLog = { logEvent : this.sandbox.stub() },
+			logger = new mw.mmv.logging.AttributionLogger(),
+			image = { author: 'foo', source: 'bar', license: {} },
+			emptyImage = {};
+
+		this.sandbox.stub( logger, 'loadDependencies' ).returns( $.Deferred().resolve() );
+		this.sandbox.stub( mw, 'log' );
+
+		logger.samplingFactor = 1;
+		logger.setEventLog( fakeEventLog );
+
+		logger.logAttribution( image );
+		assert.ok( true, 'logDimensions() did not throw errors' );
+
+		logger.logAttribution( emptyImage );
+		assert.ok( true, 'logDimensions() did not throw errors for empty image' );
+	} );
+}( mediaWiki, jQuery ) );
diff --git a/tests/qunit/mmv/logging/mmv.logging.DimensionLogger.test.js b/tests/qunit/mmv/logging/mmv.logging.DimensionLogger.test.js
new file mode 100644
index 000000000..365b0750e
--- /dev/null
+++ b/tests/qunit/mmv/logging/mmv.logging.DimensionLogger.test.js
@@ -0,0 +1,17 @@
+( function ( mw, $ ) {
+	QUnit.module( 'mmv.logging.DimensionLogger', QUnit.newMwEnvironment() );
+
+	QUnit.test( 'log()', 1, function ( assert ) {
+		var fakeEventLog = { logEvent : this.sandbox.stub() },
+			logger = new mw.mmv.logging.DimensionLogger();
+
+		this.sandbox.stub( logger, 'loadDependencies' ).returns( $.Deferred().resolve() );
+		this.sandbox.stub( mw, 'log' );
+
+		logger.samplingFactor = 1;
+		logger.setEventLog( fakeEventLog );
+
+		logger.logDimensions( 640, 480, 200, 'resize' );
+		assert.ok( true, 'logDimensions() did not throw errors' );
+	} );
+}( mediaWiki, jQuery ) );
diff --git a/tests/qunit/mmv/mmv.test.js b/tests/qunit/mmv/mmv.test.js
index 105f7d171..14eb36f51 100644
--- a/tests/qunit/mmv/mmv.test.js
+++ b/tests/qunit/mmv/mmv.test.js
@@ -116,7 +116,9 @@
 			canvas: { set : $.noop,
 				unblurWithAnimation: $.noop,
 				unblur: $.noop,
-				getCurrentImageWidths: function () { return { real : 0 }; } },
+				getCurrentImageWidths: function () { return { real : 0 }; },
+				getDimensions: function () { return {}; }
+			},
 			panel: {
 				setImageInfo: $.noop,
 				scroller: {
@@ -172,7 +174,9 @@
 			canvas : { set : $.noop,
 				unblurWithAnimation: $.noop,
 				unblur: $.noop,
-				getCurrentImageWidths : function () { return { real : 0 }; } },
+				getCurrentImageWidths : function () { return { real : 0 }; },
+				getDimensions: function () { return {}; }
+			},
 			panel : {
 				setImageInfo : $.noop,
 				scroller: {
@@ -364,8 +368,11 @@
 		viewer.ui = {
 			setFileReuseData: $.noop,
 			setupForLoad : $.noop,
-			canvas : { set : $.noop,
-				getCurrentImageWidths : function () { return { real : 0 }; } },
+			canvas : {
+				set : $.noop,
+				getCurrentImageWidths : function () { return { real : 0 }; },
+				getDimensions: function () { return {}; }
+			},
 			panel : {
 				setImageInfo : this.sandbox.stub(),
 				scroller: {