diff --git a/src/aind_data_schema/base.py b/src/aind_data_schema/base.py
index bd938bd2c..4db7bb65d 100644
--- a/src/aind_data_schema/base.py
+++ b/src/aind_data_schema/base.py
@@ -2,6 +2,7 @@
 
 import json
 import re
+import logging
 from pathlib import Path
 from typing import Any, Generic, Optional, TypeVar, get_args
 
@@ -23,6 +24,9 @@
 from aind_data_schema_models.brain_atlas import CCFStructure
 
 
+MAX_FILE_SIZE = 500 * 1024  # 500KB
+
+
 def _coerce_naive_datetime(v: Any, handler: ValidatorFunctionWrapHandler) -> AwareDatetime:
     """Validator to wrap around AwareDatetime to set a default timezone as user's locale"""
     try:
@@ -178,3 +182,7 @@ def write_standard_file(
 
         with open(filename, "w") as f:
             f.write(self.model_dump_json(indent=3))
+
+        # Check that size doesn't exceed the maximum
+        if len(self.model_dump_json(indent=3)) > MAX_FILE_SIZE:
+            logging.warning(f"File size exceeds {MAX_FILE_SIZE / 1024} KB: {filename}")
diff --git a/tests/test_base.py b/tests/test_base.py
index 9aa22a0c2..968630288 100644
--- a/tests/test_base.py
+++ b/tests/test_base.py
@@ -9,7 +9,14 @@
 from pydantic import ValidationError, create_model, SkipValidation
 from typing import Literal
 
-from aind_data_schema.base import AindGeneric, AwareDatetimeWithDefault, is_dict_corrupt, AindModel, AindCoreModel
+from aind_data_schema.base import (
+    AindGeneric,
+    AwareDatetimeWithDefault,
+    is_dict_corrupt,
+    AindModel,
+    AindCoreModel,
+    MAX_FILE_SIZE,
+)
 from aind_data_schema.core.subject import Subject
 from aind_data_schema_models.brain_atlas import CCFStructure
 
@@ -151,6 +158,20 @@ class Modelv2(AindCoreModel):
         # this is to ensure you can't get a bumped schema_version without passing validation
         self.assertRaises(ValidationError, lambda: Modelv1(**v2_from_v1.model_dump()))
 
+    @patch("builtins.open", new_callable=mock_open)
+    @patch("logging.warning")
+    def test_write_standard_file_size_warning(self, mock_logging_warning: MagicMock, mock_open: MagicMock):
+        """Tests that a warning is logged if the file size exceeds MAX_FILE_SIZE"""
+
+        s = Subject.model_construct()
+        s.subject_id = "s" * (MAX_FILE_SIZE + 1000)
+        s.write_standard_file(output_directory=Path("dir"), suffix=".foo.bar")
+
+        mock_open.assert_has_calls([call(Path("dir/subject.foo.bar"), "w")])
+        mock_logging_warning.assert_called_once_with(
+            f"File size exceeds {MAX_FILE_SIZE / 1024} KB: dir/subject.foo.bar"
+        )
+
 
 if __name__ == "__main__":
     unittest.main()