diff --git a/size_check.py b/size_check.py
new file mode 100644
index 000000000..db3c338b8
--- /dev/null
+++ b/size_check.py
@@ -0,0 +1,42 @@
+"""Sanity check image sizes and svg viewboxes."""
+from PIL import Image
+from pathlib import Path
+from lxml import etree
+
+
+def _check_image(base_dir, image_dir):
+	assert image_dir.is_dir()
+	expected_size = (int(image_dir.name), int(image_dir.name))
+
+	for image_file in image_dir.iterdir():
+		with Image.open(image_file) as image:
+			actual_size = image.size
+		if expected_size != actual_size:
+			print(f"bad_dim {image_file.relative_to(base_dir)} actual {actual_size} expected {expected_size}")
+
+def _check_svg(base_dir, svg_dir):
+	expected_viewbox = (0.0, 0.0, 128.0, 128.0)
+	for svg_file in svg_dir.iterdir():
+		if not svg_file.name.startswith("emoji_u"):
+			continue
+		assert svg_file.is_file()
+		with open(svg_file) as f:
+			actual_viewbox = etree.parse(f).getroot().attrib["viewBox"]
+		actual_viewbox = tuple(float(s) for s in actual_viewbox.split(" "))
+		if expected_viewbox != actual_viewbox:
+			print(f"bad_dim {svg_file.relative_to(base_dir)} actual {actual_viewbox} expected {expected_viewbox}")
+
+def main():
+	base_dir = Path(__file__).parent
+	image_dir = base_dir / "png"
+	svg_dir = base_dir / "svg"
+
+	assert image_dir.is_dir()
+	assert svg_dir.is_dir()
+
+	for size_dir in image_dir.iterdir():
+		_check_image(base_dir, size_dir)
+	_check_svg(base_dir, svg_dir)
+
+if __name__ == "__main__":
+   main()
\ No newline at end of file