diff --git a/selfdrive/debug/internal/qlog_size.py b/selfdrive/debug/internal/qlog_size.py
new file mode 100755
index 0000000000..bcf0781516
--- /dev/null
+++ b/selfdrive/debug/internal/qlog_size.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+import argparse
+import bz2
+from collections import defaultdict
+
+import matplotlib.pyplot as plt
+
+from cereal.services import service_list
+from tools.lib.logreader import LogReader
+from tools.lib.route import Route
+
+MIN_SIZE = 0.5  # Percent size of total to show as separate entry
+
+
+def make_pie(msgs, typ):
+  compressed_length_by_type = {k: len(bz2.compress(b"".join(v))) for k, v in msgs.items()}
+
+  total = sum(compressed_length_by_type.values())
+
+  sizes = sorted(compressed_length_by_type.items(), key=lambda kv: kv[1])
+
+  sizes_large = [(k, sz) for (k, sz) in sizes if sz >= total * MIN_SIZE / 100]
+  sizes_large += [('other', sum([sz for (_, sz) in sizes if sz < total * MIN_SIZE / 100]))]
+
+  labels, sizes = zip(*sizes_large)
+
+  plt.figure()
+  plt.title(f"{typ}")
+  plt.pie(sizes, labels=labels, autopct='%1.1f%%')
+
+
+if __name__ == "__main__":
+  parser = argparse.ArgumentParser(description='Check qlog size based on a rlog')
+  parser.add_argument('route', help='route to use')
+  parser.add_argument('segment', type=int, help='segment number to use')
+  args = parser.parse_args()
+
+  r = Route(args.route)
+  rlog = r.log_paths()[args.segment]
+  msgs = list(LogReader(rlog))
+
+  msgs_by_type = defaultdict(list)
+  for m in msgs:
+    msgs_by_type[m.which()].append(m.as_builder().to_bytes())
+
+  qlog_by_type = defaultdict(list)
+  for name, service in service_list.items():
+    if service.decimation is None:
+      continue
+
+    for i, msg in enumerate(msgs_by_type[name]):
+      if i % service.decimation == 0:
+        qlog_by_type[name].append(msg)
+
+  make_pie(msgs_by_type, 'rlog')
+  make_pie(qlog_by_type, 'qlog')
+  plt.show()