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 496598bead..8f61902205 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
@@ -148,7 +148,7 @@ import java.util.regex.Pattern;
       return Util.formatInvariant("<span style='font-size:%.2fpx;'>", sizeCssPx);
     } else if (span instanceof RelativeSizeSpan) {
       return Util.formatInvariant(
-          "<span style='font-size:%.2f%%;'>", ((RelativeSizeSpan) span).getSizeChange());
+          "<span style='font-size:%.2f%%;'>", ((RelativeSizeSpan) span).getSizeChange() * 100);
     } else if (span instanceof TypefaceSpan) {
       @Nullable String fontFamily = ((TypefaceSpan) span).getFamily();
       return fontFamily != null
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 fc4d044a53..ad62506324 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
@@ -135,7 +135,7 @@ public class SpannedToHtmlConverterTest {
   public void convert_supportsRelativeSizeSpan() {
     SpannableString spanned = new SpannableString("String with 10% section");
     spanned.setSpan(
-        new RelativeSizeSpan(/* proportion= */ 10),
+        new RelativeSizeSpan(/* proportion= */ 0.1f),
         "String with ".length(),
         "String with 10%".length(),
         Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);