diff --git a/src/olympic/studio/modlib/include/studio/selectiontracker.hpp b/src/olympic/studio/modlib/include/studio/selectiontracker.hpp
index 99484ec7..ea21bad2 100644
--- a/src/olympic/studio/modlib/include/studio/selectiontracker.hpp
+++ b/src/olympic/studio/modlib/include/studio/selectiontracker.hpp
@@ -5,6 +5,7 @@
 
 #include <ox/std/math.hpp>
 #include <ox/std/point.hpp>
+#include <ox/std/size.hpp>
 #include <ox/std/typetraits.hpp>
 
 namespace studio {
@@ -13,6 +14,10 @@ struct Selection {
 	ox::Point a, b;
 	constexpr Selection() noexcept = default;
 	constexpr Selection(ox::Point const&pA, ox::Point const&pB) noexcept: a(pA), b(pB) {}
+	[[nodiscard]]
+	constexpr ox::Size size() const noexcept {
+		return {b.x - a.x, b.y - a.y};
+	}
 };
 
 constexpr auto iterateSelection(studio::Selection const&sel, auto const&cb) {