diff --git a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverter.java b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverter.java
index f534b9e397..e06edd8ded 100644
--- a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverter.java
+++ b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverter.java
@@ -19,6 +19,7 @@ package com.google.android.exoplayer2.ui;
 import android.graphics.Typeface;
 import android.text.Html;
 import android.text.Spanned;
+import android.text.style.AbsoluteSizeSpan;
 import android.text.style.BackgroundColorSpan;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.StyleSpan;
@@ -66,8 +67,12 @@ import java.util.regex.Pattern;
    *   <li>WebView/Chromium (the intended destination of this HTML) gracefully handles overlapping
    *       tags and usually renders the same result as spanned text in a TextView.
    * </ul>
+   *
+   * @param text The (possibly span-styled) text to convert to HTML.
+   * @param displayDensity The screen density of the device. WebView treats 1 CSS px as one Android
+   *     dp, so to convert size values from Android px to CSS px we need to know the screen density.
    */
-  public static String convert(@Nullable CharSequence text) {
+  public static String convert(@Nullable CharSequence text, float displayDensity) {
     if (text == null) {
       return "";
     }
@@ -75,7 +80,7 @@ import java.util.regex.Pattern;
       return escapeHtml(text);
     }
     Spanned spanned = (Spanned) text;
-    SparseArray<Transition> spanTransitions = findSpanTransitions(spanned);
+    SparseArray<Transition> spanTransitions = findSpanTransitions(spanned, displayDensity);
 
     StringBuilder html = new StringBuilder(spanned.length());
     int previousTransition = 0;
@@ -100,11 +105,12 @@ import java.util.regex.Pattern;
     return html.toString();
   }
 
-  private static SparseArray<Transition> findSpanTransitions(Spanned spanned) {
+  private static SparseArray<Transition> findSpanTransitions(
+      Spanned spanned, float displayDensity) {
     SparseArray<Transition> spanTransitions = new SparseArray<>();
 
     for (Object span : spanned.getSpans(0, spanned.length(), Object.class)) {
-      @Nullable String openingTag = getOpeningTag(span);
+      @Nullable String openingTag = getOpeningTag(span, displayDensity);
       @Nullable String closingTag = getClosingTag(span);
       int spanStart = spanned.getSpanStart(span);
       int spanEnd = spanned.getSpanEnd(span);
@@ -120,7 +126,7 @@ import java.util.regex.Pattern;
   }
 
   @Nullable
-  private static String getOpeningTag(Object span) {
+  private static String getOpeningTag(Object span, float displayDensity) {
     if (span instanceof ForegroundColorSpan) {
       ForegroundColorSpan colorSpan = (ForegroundColorSpan) span;
       return Util.formatInvariant(
@@ -132,6 +138,13 @@ import java.util.regex.Pattern;
           HtmlUtils.toCssRgba(colorSpan.getBackgroundColor()));
     } else if (span instanceof HorizontalTextInVerticalContextSpan) {
       return "<span style='text-combine-upright:all;'>";
+    } else if (span instanceof AbsoluteSizeSpan) {
+      AbsoluteSizeSpan absoluteSizeSpan = (AbsoluteSizeSpan) span;
+      float sizeCssPx =
+          absoluteSizeSpan.getDip()
+              ? absoluteSizeSpan.getSize()
+              : absoluteSizeSpan.getSize() / displayDensity;
+      return Util.formatInvariant("<span style='font-size:%.2fpx;'>", sizeCssPx);
     } else if (span instanceof TypefaceSpan) {
       @Nullable String fontFamily = ((TypefaceSpan) span).getFamily();
       return fontFamily != null
@@ -171,7 +184,8 @@ import java.util.regex.Pattern;
   private static String getClosingTag(Object span) {
     if (span instanceof ForegroundColorSpan
         || span instanceof BackgroundColorSpan
-        || span instanceof HorizontalTextInVerticalContextSpan) {
+        || span instanceof HorizontalTextInVerticalContextSpan
+        || span instanceof AbsoluteSizeSpan) {
       return "</span>";
     } else if (span instanceof TypefaceSpan) {
       @Nullable String fontFamily = ((TypefaceSpan) span).getFamily();
diff --git a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleWebView.java b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleWebView.java
index 480d057212..ee081f384e 100644
--- a/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleWebView.java
+++ b/library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleWebView.java
@@ -309,7 +309,9 @@ import java.util.List;
                   horizontalTranslatePercent,
                   verticalTranslatePercent))
           .append(Util.formatInvariant("<span style=\"background-color:%s;\">", backgroundColorCss))
-          .append(SpannedToHtmlConverter.convert(cue.text))
+          .append(
+              SpannedToHtmlConverter.convert(
+                  cue.text, getContext().getResources().getDisplayMetrics().density))
           .append("</span>")
           .append("</div>");
     }
diff --git a/library/ui/src/test/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverterTest.java b/library/ui/src/test/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverterTest.java
index b6a6c5a323..c64d5cabcf 100644
--- a/library/ui/src/test/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverterTest.java
+++ b/library/ui/src/test/java/com/google/android/exoplayer2/ui/SpannedToHtmlConverterTest.java
@@ -22,21 +22,31 @@ import android.graphics.Color;
 import android.graphics.Typeface;
 import android.text.SpannableString;
 import android.text.Spanned;
+import android.text.style.AbsoluteSizeSpan;
 import android.text.style.BackgroundColorSpan;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.StyleSpan;
 import android.text.style.TypefaceSpan;
 import android.text.style.UnderlineSpan;
+import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
 import com.google.android.exoplayer2.text.span.RubySpan;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.robolectric.annotation.Config;
 
 /** Tests for {@link SpannedToHtmlConverter}. */
 @RunWith(AndroidJUnit4.class)
 public class SpannedToHtmlConverterTest {
 
+  private final float displayDensity;
+
+  public SpannedToHtmlConverterTest() {
+    displayDensity =
+        ApplicationProvider.getApplicationContext().getResources().getDisplayMetrics().density;
+  }
+
   @Test
   public void convert_supportsForegroundColorSpan() {
     SpannableString spanned = new SpannableString("String with colored section");
@@ -46,7 +56,7 @@ public class SpannedToHtmlConverterTest {
         "String with colored".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo("String with <span style='color:rgba(64,32,16,0.200);'>colored</span> section");
@@ -61,7 +71,7 @@ public class SpannedToHtmlConverterTest {
         "String with highlighted".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo(
@@ -78,7 +88,7 @@ public class SpannedToHtmlConverterTest {
         "Vertical text with 123".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo(
@@ -86,6 +96,40 @@ public class SpannedToHtmlConverterTest {
                 + "horizontal numbers");
   }
 
+  // Set the screen density so we see that px are handled differently to dp.
+  @Config(qualifiers = "xhdpi")
+  @Test
+  public void convert_supportsAbsoluteSizeSpan_px() {
+    SpannableString spanned = new SpannableString("String with 10px section");
+    spanned.setSpan(
+        new AbsoluteSizeSpan(/* size= */ 10, /* dip= */ false),
+        "String with ".length(),
+        "String with 10px".length(),
+        Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
+
+    // 10 Android px are converted to 5 CSS px because WebView treats 1 CSS px as 1 Android dp
+    // and we're using screen density xhdpi i.e. density=2.
+    assertThat(html).isEqualTo("String with <span style='font-size:5.00px;'>10px</span> section");
+  }
+
+  // Set the screen density so we see that px are handled differently to dp.
+  @Config(qualifiers = "xhdpi")
+  @Test
+  public void convert_supportsAbsoluteSizeSpan_dp() {
+    SpannableString spanned = new SpannableString("String with 10dp section");
+    spanned.setSpan(
+        new AbsoluteSizeSpan(/* size= */ 10, /* dip= */ true),
+        "String with ".length(),
+        "String with 10dp".length(),
+        Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
+
+    assertThat(html).isEqualTo("String with <span style='font-size:10.00px;'>10dp</span> section");
+  }
+
   @Test
   public void convert_supportsTypefaceSpan() {
     SpannableString spanned = new SpannableString("String with Times New Roman section");
@@ -95,7 +139,7 @@ public class SpannedToHtmlConverterTest {
         "String with Times New Roman".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo(
@@ -112,7 +156,7 @@ public class SpannedToHtmlConverterTest {
         "String with unstyled".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with unstyled section");
   }
@@ -137,7 +181,7 @@ public class SpannedToHtmlConverterTest {
         "String with bold, italic and bold-italic".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo(
@@ -159,7 +203,7 @@ public class SpannedToHtmlConverterTest {
         "String with over-annotated and under-annotated".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html)
         .isEqualTo(
@@ -185,28 +229,31 @@ public class SpannedToHtmlConverterTest {
         "String with underlined".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with <u>underlined</u> section.");
   }
 
   @Test
   public void convert_escapesHtmlInUnspannedString() {
-    String html = SpannedToHtmlConverter.convert("String with <b>bold</b> tags");
+    String html = SpannedToHtmlConverter.convert("String with <b>bold</b> tags", displayDensity);
 
     assertThat(html).isEqualTo("String with &lt;b&gt;bold&lt;/b&gt; tags");
   }
 
   @Test
   public void convert_handlesLinebreakInUnspannedString() {
-    String html = SpannedToHtmlConverter.convert("String with\nnew line and\r\ncrlf style too");
+    String html =
+        SpannedToHtmlConverter.convert(
+            "String with\nnew line and\r\ncrlf style too", displayDensity);
 
     assertThat(html).isEqualTo("String with<br>new line and<br>crlf style too");
   }
 
   @Test
   public void convert_doesntConvertAmpersandLineFeedToBrTag() {
-    String html = SpannedToHtmlConverter.convert("String with&#10;new line ampersand code");
+    String html =
+        SpannedToHtmlConverter.convert("String with&#10;new line ampersand code", displayDensity);
 
     assertThat(html).isEqualTo("String with&amp;#10;new line ampersand code");
   }
@@ -220,14 +267,16 @@ public class SpannedToHtmlConverterTest {
         "String with <foo>unrecognised</foo>".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with <i>&lt;foo&gt;unrecognised&lt;/foo&gt;</i> tags");
   }
 
   @Test
   public void convert_handlesLinebreakInSpannedString() {
-    String html = SpannedToHtmlConverter.convert("String with\nnew line and\r\ncrlf style too");
+    String html =
+        SpannedToHtmlConverter.convert(
+            "String with\nnew line and\r\ncrlf style too", displayDensity);
 
     assertThat(html).isEqualTo("String with<br>new line and<br>crlf style too");
   }
@@ -236,7 +285,7 @@ public class SpannedToHtmlConverterTest {
   public void convert_convertsNonAsciiCharactersToAmpersandCodes() {
     String html =
         SpannedToHtmlConverter.convert(
-            new SpannableString("Strìng with 優しいの non-ASCII characters"));
+            new SpannableString("Strìng with 優しいの non-ASCII characters"), displayDensity);
 
     assertThat(html)
         .isEqualTo("Str&#236;ng with &#20778;&#12375;&#12356;&#12398; non-ASCII characters");
@@ -256,7 +305,7 @@ public class SpannedToHtmlConverterTest {
         "String with unrecognised".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with unrecognised span");
   }
@@ -270,7 +319,7 @@ public class SpannedToHtmlConverterTest {
     spanned.setSpan(new StyleSpan(Typeface.ITALIC), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
     spanned.setSpan(new UnderlineSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with <b><i><u>italic-bold-underlined</u></i></b> section");
   }
@@ -287,7 +336,7 @@ public class SpannedToHtmlConverterTest {
         "String with italic and bold".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("String with <i>italic and <b>bold</b></i> section");
   }
@@ -306,7 +355,7 @@ public class SpannedToHtmlConverterTest {
         "String with italic and bold section".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
 
-    String html = SpannedToHtmlConverter.convert(spanned);
+    String html = SpannedToHtmlConverter.convert(spanned, displayDensity);
 
     assertThat(html).isEqualTo("<i>String with italic <b>and bold</i> section</b>");
   }