diff --git a/backend/open_webui/utils/context_compaction.py b/backend/open_webui/utils/context_compaction.py
index aeb4e9875e..d9cb7879f7 100644
--- a/backend/open_webui/utils/context_compaction.py
+++ b/backend/open_webui/utils/context_compaction.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import logging
+import re
 from typing import Any
 
 from fastapi.responses import JSONResponse
@@ -19,6 +20,8 @@ from open_webui.utils.task import (
 
 log = logging.getLogger(__name__)
 
+BASE64_DATA_URI_RE = re.compile(r'data:[\w/+.;=%-]*;base64,[A-Za-z0-9+/=]*')
+
 DEFAULT_CONTEXT_COMPACTION_PROMPT = """### Task:
 Summarize the conversation history that will be compacted out of the active chat context.
 
@@ -439,7 +442,10 @@ def _estimate_messages_tokens(messages: list[dict]) -> int:
 
         total += _estimate_tokens(message.get('output'))
         total += _estimate_tokens(message.get('tool_calls'))
-        total += _estimate_tokens(message.get('files'))
+        files = message.get('files')
+        if files:
+            # Inline data is not part of the file tags sent to the model.
+            total += _estimate_tokens(BASE64_DATA_URI_RE.sub('', JSONCodec.dumps(files, ensure_ascii=False)))
     return total
 
 
diff --git a/src/lib/components/chat/Chat.svelte b/src/lib/components/chat/Chat.svelte
index ba8c2ccb7e..adfe074fd5 100644
--- a/src/lib/components/chat/Chat.svelte
+++ b/src/lib/components/chat/Chat.svelte
@@ -257,7 +257,11 @@
 			let next = total + 4 + estimateTokens(message.content);
 			next += estimateTokens(message.output);
 			next += estimateTokens(message.tool_calls);
-			next += estimateTokens(message.files);
+			if (message.files?.length) {
+				next += estimateTokens(
+					JSON.stringify(message.files).replace(/data:[\w/+.;=%-]*;base64,[A-Za-z0-9+/=]*/g, '')
+				);
+			}
 			return next;
 		}, 0);
 
diff --git a/src/lib/components/chat/MessageInput.svelte b/src/lib/components/chat/MessageInput.svelte
index 2adbc27bb3..c621071884 100644
--- a/src/lib/components/chat/MessageInput.svelte
+++ b/src/lib/components/chat/MessageInput.svelte
@@ -473,7 +473,11 @@
 			let next = total + 4 + estimateTokens(message.content);
 			next += estimateTokens(message.output);
 			next += estimateTokens(message.tool_calls);
-			next += estimateTokens(message.files);
+			if (message.files?.length) {
+				next += estimateTokens(
+					JSON.stringify(message.files).replace(/data:[\w/+.;=%-]*;base64,[A-Za-z0-9+/=]*/g, '')
+				);
+			}
 			return next;
 		}, 0);