diff --git a/ext/resize/script.js b/ext/resize/script.js
new file mode 100644
index 00000000..21edb03d
--- /dev/null
+++ b/ext/resize/script.js
@@ -0,0 +1,19 @@
+$(function() {
+	var original_width = $("#original_width").val();
+	var original_height = $("#original_height").val();
+
+	$("#resize_width").change(function() {
+		if($("#resize_aspect").prop("checked")) {
+			$("#resize_height").val(
+				Math.round($("#resize_width").val() / original_width * original_height)
+			);
+		}
+	});
+	$("#resize_height").change(function() {
+		if($("#resize_aspect").prop("checked")) {
+			$("#resize_width").val(
+				Math.round($("#resize_height").val() / original_height * original_width)
+			);
+		}
+	});
+});