diff --git a/Userland/Libraries/LibWeb/CMakeLists.txt b/Userland/Libraries/LibWeb/CMakeLists.txt
index c1265a26fb..1c22c1eccd 100644
--- a/Userland/Libraries/LibWeb/CMakeLists.txt
+++ b/Userland/Libraries/LibWeb/CMakeLists.txt
@@ -40,6 +40,7 @@ set(SOURCES
     CSS/Display.cpp
     CSS/FontFace.cpp
     CSS/Frequency.cpp
+    CSS/GridTrackSize.cpp
     CSS/Length.cpp
     CSS/MediaList.cpp
     CSS/MediaQuery.cpp
diff --git a/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp b/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp
new file mode 100644
index 0000000000..5c4e0f478c
--- /dev/null
+++ b/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2022, Martin Falisse <mfalisse@outlook.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "GridTrackSize.h"
+#include <AK/String.h>
+#include <LibWeb/CSS/Length.h>
+#include <LibWeb/CSS/Percentage.h>
+#include <LibWeb/CSS/StyleValue.h>
+
+namespace Web::CSS {
+
+GridTrackSize::GridTrackSize(Length length)
+    : m_type(Type::Length)
+    , m_length(length)
+{
+}
+
+GridTrackSize::GridTrackSize(Percentage percentage)
+    : m_type(Type::Percentage)
+    , m_percentage(percentage)
+{
+}
+
+GridTrackSize::GridTrackSize(int flexible_length)
+    : m_type(Type::FlexibleLength)
+    , m_flexible_length(flexible_length)
+{
+}
+
+String GridTrackSize::to_string() const
+{
+    switch (m_type) {
+    case Type::Length:
+        return m_length.to_string();
+    case Type::Percentage:
+        return m_percentage.to_string();
+    case Type::FlexibleLength:
+        return String::formatted("{}fr", m_flexible_length);
+    }
+    VERIFY_NOT_REACHED();
+}
+
+}
diff --git a/Userland/Libraries/LibWeb/CSS/GridTrackSize.h b/Userland/Libraries/LibWeb/CSS/GridTrackSize.h
new file mode 100644
index 0000000000..89ff2361c0
--- /dev/null
+++ b/Userland/Libraries/LibWeb/CSS/GridTrackSize.h
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2022, Martin Falisse <mfalisse@outlook.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/CSS/Length.h>
+#include <LibWeb/CSS/Percentage.h>
+
+namespace Web::CSS {
+
+class GridTrackSize {
+public:
+    enum class Type {
+        Length,
+        Percentage,
+        FlexibleLength,
+        // TODO: MinMax
+        // TODO: Repeat
+        // TODO: Max-Content
+    };
+
+    GridTrackSize(Length);
+    GridTrackSize(Percentage);
+    GridTrackSize(int);
+
+    Type type() const { return m_type; }
+
+    bool is_length() const { return m_type == Type::Length; }
+    bool is_percentage() const { return m_type == Type::Percentage; }
+    bool is_flexible_length() const { return m_type == Type::FlexibleLength; }
+
+    Length length() const { return m_length; }
+    Percentage percentage() const { return m_percentage; }
+    int flexible_length() const { return m_flexible_length; }
+
+    String to_string() const;
+    bool operator==(GridTrackSize const& other) const
+    {
+        return m_type == other.type()
+            && m_length == other.length()
+            && m_percentage == other.percentage()
+            && m_flexible_length == other.flexible_length();
+    }
+
+private:
+    Type m_type;
+    Length m_length { Length::make_px(0) };
+    Percentage m_percentage { Percentage(0) };
+    int m_flexible_length { 0 };
+};
+
+}
diff --git a/Userland/Libraries/LibWeb/Forward.h b/Userland/Libraries/LibWeb/Forward.h
index fc136593bc..ff66233853 100644
--- a/Userland/Libraries/LibWeb/Forward.h
+++ b/Userland/Libraries/LibWeb/Forward.h
@@ -57,6 +57,7 @@ class FontStyleValue;
 class Frequency;
 class FrequencyPercentage;
 class FrequencyStyleValue;
+class GridTrackSize;
 class IdentifierStyleValue;
 class ImageStyleValue;
 class InheritStyleValue;