diff --git a/Tests/LibWeb/Ref/assets/2x2checkerboard.png b/Tests/LibWeb/Ref/assets/2x2checkerboard.png
new file mode 100644
index 00000000000..83b96959786
Binary files /dev/null and b/Tests/LibWeb/Ref/assets/2x2checkerboard.png differ
diff --git a/Tests/LibWeb/Ref/background-size-calc.html b/Tests/LibWeb/Ref/background-size-calc.html
new file mode 100644
index 00000000000..2ad3ee97c80
--- /dev/null
+++ b/Tests/LibWeb/Ref/background-size-calc.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <link rel="match" href="reference/background-size-calc-ref.html" />
+    <style>
+        span {
+            display: inline-block;
+            min-width: 12px;
+            min-height: 12px;
+            background-image: url("assets/2x2checkerboard.png");
+            background-size: calc(max(0.75em, 12px));
+        }
+    </style>
+</head>
+<body><span></span><img src="assets/2x2checkerboard.png">
diff --git a/Tests/LibWeb/Ref/reference/background-size-calc-ref.html b/Tests/LibWeb/Ref/reference/background-size-calc-ref.html
new file mode 100644
index 00000000000..00a8db96ceb
--- /dev/null
+++ b/Tests/LibWeb/Ref/reference/background-size-calc-ref.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <style>
+        span {
+            display: inline-block;
+            min-width: 12px;
+            min-height: 12px;
+            background-image: url("../assets/2x2checkerboard.png");
+            background-size: calc(max(0.75em, 12px));
+        }
+    </style>
+</head>
+<body><span></span><img src="../assets/2x2checkerboard.png">
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index 148e7b1bd3b..4fbba0574f8 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -3169,6 +3169,8 @@ RefPtr<StyleValue> Parser::parse_single_background_size_value(TokenStream<Compon
             return LengthPercentage { style_value.as_percentage().percentage() };
         if (style_value.is_length())
             return LengthPercentage { style_value.as_length().length() };
+        if (style_value.is_calculated())
+            return LengthPercentage { style_value.as_calculated() };
         return {};
     };
 
