diff --git a/tools/free_space.awk b/tools/free_space.awk
new file mode 100644
index 000000000..1f2b04415
--- /dev/null
+++ b/tools/free_space.awk
@@ -0,0 +1,13 @@
+#!/usr/bin/awk -f
+
+# Usage: tools/free_space.awk pokecrystal.map
+
+BEGIN {
+	total = free = 16384 * 128
+}
+/^  SECTION: \$[0-7]/ {
+	free -= strtonum("0x" substr($3, 3))
+}
+END {
+	printf "Free space: %d/%d (%.2f%%)\n", free, total, free * 100 / total
+}