diff --git a/app/documentinfoprovider.cpp b/app/documentinfoprovider.cpp
--- a/app/documentinfoprovider.cpp
+++ b/app/documentinfoprovider.cpp
@@ -23,7 +23,7 @@
 
 // Qt
 #include <QPixmap>
-
+#include <QApplication>
 // KDE
 
 // Local
@@ -50,7 +50,8 @@
     Q_ASSERT(outFullSize);
     *outPix = QPixmap();
     *outFullSize = QSize();
-    const int pixelSize = ThumbnailGroup::pixelSize(group);
+    qreal dpr = qApp->devicePixelRatio();
+    const int pixelSize = ThumbnailGroup::pixelSize(group) * dpr;
 
     Document::Ptr doc = DocumentFactory::instance()->getCachedDocument(url);
     if (!doc) {
diff --git a/lib/thumbnailprovider/thumbnailgenerator.cpp b/lib/thumbnailprovider/thumbnailgenerator.cpp
--- a/lib/thumbnailprovider/thumbnailgenerator.cpp
+++ b/lib/thumbnailprovider/thumbnailgenerator.cpp
@@ -34,6 +34,7 @@
 #endif
 
 // Qt
+#include <QApplication>
 #include <QImageReader>
 #include <QMatrix>
 #include <QBuffer>
@@ -270,7 +271,8 @@
         {
             QMutexLocker lock(&mMutex);
             pixPath = mPixPath;
-            pixelSize = ThumbnailGroup::pixelSize(mThumbnailGroup);
+            qreal dpr = qApp->devicePixelRatio();
+            pixelSize = ThumbnailGroup::pixelSize(mThumbnailGroup) * dpr;
         }
 
         Q_ASSERT(!pixPath.isNull());
diff --git a/lib/thumbnailprovider/thumbnailprovider.cpp b/lib/thumbnailprovider/thumbnailprovider.cpp
--- a/lib/thumbnailprovider/thumbnailprovider.cpp
+++ b/lib/thumbnailprovider/thumbnailprovider.cpp
@@ -399,7 +399,8 @@
         if (largeImage.isNull()) {
             return image;
         }
-        int size = ThumbnailGroup::pixelSize(ThumbnailGroup::Normal);
+        qreal dpr = qApp->devicePixelRatio();
+        int size = ThumbnailGroup::pixelSize(ThumbnailGroup::Normal) * dpr;
         image = largeImage.scaled(size, size, Qt::KeepAspectRatio, Qt::SmoothTransformation);
         Q_FOREACH(const QString& key, largeImage.textKeys()) {
             QString text = largeImage.text(key);
@@ -494,7 +495,8 @@
         mState = STATE_PREVIEWJOB;
         KFileItemList list;
         list.append(mCurrentItem);
-        const int pixelSize = ThumbnailGroup::pixelSize(mThumbnailGroup);
+        qreal dpr = qApp->devicePixelRatio();
+        const int pixelSize = ThumbnailGroup::pixelSize(mThumbnailGroup) * dpr;
         if (mPreviewPlugins.isEmpty()) {
             mPreviewPlugins = KIO::PreviewJob::availablePlugins();
         }
diff --git a/lib/thumbnailview/previewitemdelegate.cpp b/lib/thumbnailview/previewitemdelegate.cpp
--- a/lib/thumbnailview/previewitemdelegate.cpp
+++ b/lib/thumbnailview/previewitemdelegate.cpp
@@ -718,11 +718,12 @@
     fgColor = viewport->palette().color(viewport->foregroundRole());
 
     // Compute thumbnailRect
+    qreal dpr = qApp->devicePixelRatio();
     QRect thumbnailRect = QRect(
-                              rect.left() + (rect.width() - thumbnailPix.width()) / 2,
-                              rect.top() + (thumbnailHeight - thumbnailPix.height()) + ITEM_MARGIN,
-                              thumbnailPix.width(),
-                              thumbnailPix.height());
+                              rect.left() + (rect.width() - thumbnailPix.width() / dpr) / 2,
+                              rect.top() + (thumbnailHeight - thumbnailPix.height() / dpr) + ITEM_MARGIN,
+                              thumbnailPix.width() / dpr,
+                              thumbnailPix.height() / dpr);
 
     // Draw background
     const QRect backgroundRect = thumbnailRect.adjusted(-ITEM_MARGIN, -ITEM_MARGIN, ITEM_MARGIN, ITEM_MARGIN);
diff --git a/lib/thumbnailview/thumbnailview.cpp b/lib/thumbnailview/thumbnailview.cpp
--- a/lib/thumbnailview/thumbnailview.cpp
+++ b/lib/thumbnailview/thumbnailview.cpp
@@ -105,8 +105,10 @@
      */
     void initAsIcon(const QPixmap& pix)
     {
+        qreal dpr = qApp->devicePixelRatio();
         mGroupPix = pix;
-        int largeGroupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::Large);
+        mGroupPix.setDevicePixelRatio(dpr);
+        int largeGroupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::Large) * dpr;
         mFullSize = QSize(largeGroupSize, largeGroupSize);
     }
 
@@ -230,10 +232,11 @@
 
     void roughAdjustThumbnail(Thumbnail* thumbnail)
     {
+        qreal dpr = qApp->devicePixelRatio();
         const QPixmap& mGroupPix = thumbnail->mGroupPix;
         const int groupSize = qMax(mGroupPix.width(), mGroupPix.height());
         const int fullSize = qMax(thumbnail->mFullSize.width(), thumbnail->mFullSize.height());
-        if (fullSize == groupSize && mGroupPix.height() <= mThumbnailSize.height() && mGroupPix.width() <= mThumbnailSize.width()) {
+        if (fullSize == groupSize && mGroupPix.height() <= mThumbnailSize.height() * dpr && mGroupPix.width() <= mThumbnailSize.width() * dpr) {
             thumbnail->mAdjustedPix = mGroupPix;
             thumbnail->mRough = false;
         } else {
@@ -257,25 +260,22 @@
 
     QPixmap scale(const QPixmap& pix, Qt::TransformationMode transformationMode)
     {
+        qreal dpr = qApp->devicePixelRatio();
         switch (mScaleMode) {
         case ThumbnailView::ScaleToFit:
-            return pix.scaled(mThumbnailSize.width(), mThumbnailSize.height(), Qt::KeepAspectRatio, transformationMode);
-            break;
+            return pix.scaled(mThumbnailSize.width() * dpr, mThumbnailSize.height() * dpr, Qt::KeepAspectRatio, transformationMode);
         case ThumbnailView::ScaleToSquare: {
             int minSize = qMin(pix.width(), pix.height());
             QPixmap pix2 = pix.copy((pix.width() - minSize) / 2, (pix.height() - minSize) / 2, minSize, minSize);
-            return pix2.scaled(mThumbnailSize.width(), mThumbnailSize.height(), Qt::KeepAspectRatio, transformationMode);
+            return pix2.scaled(mThumbnailSize.width() * dpr, mThumbnailSize.height() * dpr, Qt::KeepAspectRatio, transformationMode);
         }
         case ThumbnailView::ScaleToHeight:
-            return pix.scaledToHeight(mThumbnailSize.height(), transformationMode);
-            break;
+            return pix.scaledToHeight(mThumbnailSize.height() * dpr, transformationMode);
         case ThumbnailView::ScaleToWidth:
-            return pix.scaledToWidth(mThumbnailSize.width(), transformationMode);
-            break;
+            return pix.scaledToWidth(mThumbnailSize.width() * dpr, transformationMode);
+        default:
+            return QPixmap();
         }
-        // Keep compiler happy
-        Q_ASSERT(0);
-        return QPixmap();
     }
 };
 
@@ -364,20 +364,23 @@
 
 void ThumbnailView::updateThumbnailSize()
 {
-    QSize value = d->mThumbnailSize;
+    QSize thumbnailSize = d->mThumbnailSize;
     // mWaitingThumbnail
     int waitingThumbnailSize;
-    if (value.width() > 64) {
+    if (thumbnailSize.width() > 64) {
         waitingThumbnailSize = 48;
     } else {
         waitingThumbnailSize = 32;
     }
-    QPixmap icon = DesktopIcon("chronometer", waitingThumbnailSize);
-    QPixmap pix(value);
+    qreal dpr = qApp->devicePixelRatio();
+    QPixmap icon = DesktopIcon("chronometer", waitingThumbnailSize * dpr);
+    icon.setDevicePixelRatio(dpr);
+    QPixmap pix(thumbnailSize * dpr);
+    pix.setDevicePixelRatio(dpr);
     pix.fill(Qt::transparent);
     QPainter painter(&pix);
     painter.setOpacity(0.5);
-    painter.drawPixmap((value.width() - icon.width()) / 2, (value.height() - icon.height()) / 2, icon);
+    painter.drawPixmap((thumbnailSize.width() - icon.width() / dpr) / 2, (thumbnailSize.height() - icon.height() / dpr) / 2, icon);
     painter.end();
     d->mWaitingThumbnail = pix;
 
@@ -393,8 +396,8 @@
         it.value().mAdjustedPix = QPixmap();
     }
 
-    thumbnailSizeChanged(value);
-    thumbnailWidthChanged(value.width());
+    thumbnailSizeChanged(thumbnailSize);
+    thumbnailWidthChanged(thumbnailSize.width());
     if (d->mScaleMode != ScaleToFit) {
         scheduleDelayedItemsLayout();
     }
@@ -552,8 +555,10 @@
     }
     Thumbnail& thumbnail = it.value();
     thumbnail.mGroupPix = pixmap;
+    qreal dpr = qApp->devicePixelRatio();
+    thumbnail.mGroupPix.setDevicePixelRatio(dpr);
     thumbnail.mAdjustedPix = QPixmap();
-    int largeGroupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::Large);
+    int largeGroupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::Large) * dpr;
     thumbnail.mFullSize = size.isValid() ? size : QSize(largeGroupSize, largeGroupSize);
     thumbnail.mRealFullSize = size;
     thumbnail.mWaitingForThumbnail = false;
@@ -567,6 +572,7 @@
 
 void ThumbnailView::setBrokenThumbnail(const KFileItem& item)
 {
+    qreal dpr = qApp->devicePixelRatio();
     ThumbnailForUrl::iterator it = d->mThumbnailForUrl.find(item.url());
     if (it == d->mThumbnailForUrl.end()) {
         return;
@@ -577,7 +583,7 @@
         // Special case for videos because our kde install may come without
         // support for video thumbnails so we show the mimetype icon instead of
         // a broken image icon
-        QPixmap pix = KIconLoader::global()->loadMimeTypeIcon(item.iconName(), KIconLoader::Desktop, d->mThumbnailSize.height());
+        QPixmap pix = KIconLoader::global()->loadMimeTypeIcon(item.iconName(), KIconLoader::Desktop, d->mThumbnailSize.height() * dpr);
         thumbnail.initAsIcon(pix);
     } else if (kind == MimeTypeUtils::KIND_DIR) {
         // Special case for folders because ThumbnailProvider does not return a
@@ -614,9 +620,10 @@
     // If dir or archive, generate a thumbnail from fileitem pixmap
     MimeTypeUtils::Kind kind = MimeTypeUtils::fileItemKind(item);
     if (kind == MimeTypeUtils::KIND_ARCHIVE || kind == MimeTypeUtils::KIND_DIR) {
-        int groupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::fromPixelSize(d->mThumbnailSize.height()));
+        qreal dpr = qApp->devicePixelRatio();
+        int groupSize = ThumbnailGroup::pixelSize(ThumbnailGroup::fromPixelSize(d->mThumbnailSize.height())) * dpr;
         if (thumbnail.mGroupPix.isNull() || thumbnail.mGroupPix.height() < groupSize) {
-            QPixmap pix = KIconLoader::global()->loadMimeTypeIcon(item.iconName(), KIconLoader::Desktop, d->mThumbnailSize.height());
+            QPixmap pix = KIconLoader::global()->loadMimeTypeIcon(item.iconName(), KIconLoader::Desktop, d->mThumbnailSize.height() * dpr);
 
             thumbnail.initAsIcon(pix);
             if (kind == MimeTypeUtils::KIND_ARCHIVE) {
@@ -824,7 +831,8 @@
 
         // Filter out items which already have a thumbnail
         ThumbnailForUrl::ConstIterator it = d->mThumbnailForUrl.constFind(url);
-        if (it != d->mThumbnailForUrl.constEnd() && it.value().isGroupPixAdaptedForSize(d->mThumbnailSize.height())) {
+        qreal dpr = qApp->devicePixelRatio();
+        if (it != d->mThumbnailForUrl.constEnd() && it.value().isGroupPixAdaptedForSize(d->mThumbnailSize.height() * dpr)) {
             continue;
         }