diff --git a/dvuploader/directupload.py b/dvuploader/directupload.py
index 9e2d974..0d8a666 100644
--- a/dvuploader/directupload.py
+++ b/dvuploader/directupload.py
@@ -2,11 +2,12 @@
 import json
 import os
 from io import BytesIO
-from typing import AsyncGenerator, Dict, List, Optional, Tuple
+from typing import AsyncGenerator, Dict, List, Optional, Tuple, Union
 from urllib.parse import urljoin
 
 import aiofiles
 import httpx
+from aiofiles.threadpool.binary import AsyncBufferedReader
 from rich.progress import Progress, TaskID
 
 from dvuploader.file import File
@@ -33,6 +34,8 @@
 UPLOAD_ENDPOINT = "/api/datasets/:persistentId/addFiles?persistentId="
 REPLACE_ENDPOINT = "/api/datasets/:persistentId/replaceFiles?persistentId="
 
+DEFAULT_CHUNK_SIZE = 1024 * 1024  # 1MB
+
 # Initialize logging
 init_logging()
 
@@ -399,34 +402,25 @@ async def _chunked_upload(
         )
 
     async with aiofiles.open(file.filepath, "rb") as f:
-        chunk = await f.read(chunk_size)
-        e_tags.append(
-            await _upload_chunk(
-                session=session,
-                url=next(urls),
-                file=BytesIO(chunk),
-                progress=progress,
-                pbar=pbar,
-                hash_func=file.checksum._hash_fun,
+        filesize = os.path.getsize(file.filepath)
+        current_position = 0
+
+        while current_position < filesize:
+            current_chunk_size = min(chunk_size, filesize - current_position)
+
+            e_tags.append(
+                await _upload_chunk(
+                    session=session,
+                    url=next(urls),
+                    file=f,
+                    progress=progress,
+                    pbar=pbar,
+                    hash_func=file.checksum._hash_fun,
+                    chunk_size=current_chunk_size,
+                )
             )
-        )
-
-        while chunk:
-            chunk = await f.read(chunk_size)
 
-            if not chunk:
-                break
-            else:
-                e_tags.append(
-                    await _upload_chunk(
-                        session=session,
-                        url=next(urls),
-                        file=BytesIO(chunk),
-                        progress=progress,
-                        pbar=pbar,
-                        hash_func=file.checksum._hash_fun,
-                    )
-                )
+            current_position += current_chunk_size
 
     return e_tags
 
@@ -452,10 +446,11 @@ def _validate_ticket_response(response: Dict) -> None:
 async def _upload_chunk(
     session: httpx.AsyncClient,
     url: str,
-    file: BytesIO,
+    file: Union[BytesIO, AsyncBufferedReader],
     progress: Progress,
     pbar: TaskID,
     hash_func,
+    chunk_size: int,
 ):
     """
     Upload a single chunk of data.
@@ -467,6 +462,7 @@ async def _upload_chunk(
         progress (Progress): Progress tracking object.
         pbar (TaskID): Progress bar task ID.
         hash_func: Hash function for checksum.
+        chunk_size (int): Size of chunk to upload.
 
     Returns:
         str: ETag from server response.
@@ -475,8 +471,13 @@ async def _upload_chunk(
     if TESTING:
         url = url.replace("localstack", "localhost", 1)
 
+    if isinstance(file, BytesIO):
+        file_size = len(file.getvalue())
+    else:
+        file_size = chunk_size
+
     headers = {
-        "Content-length": str(len(file.getvalue())),
+        "Content-length": str(file_size),
     }
 
     params = {
@@ -487,6 +488,7 @@ async def _upload_chunk(
             progress=progress,
             pbar=pbar,
             hash_func=hash_func,
+            chunk_size=chunk_size,
         ),
     }
 
@@ -664,10 +666,11 @@ async def _multipart_json_data_request(
 
 
 async def upload_bytes(
-    file: BytesIO,
+    file: Union[BytesIO, AsyncBufferedReader],
     progress: Progress,
     pbar: TaskID,
     hash_func,
+    chunk_size: Optional[int] = None,
 ) -> AsyncGenerator[bytes, None]:
     """
     Generate chunks of file data for upload.
@@ -681,12 +684,27 @@ async def upload_bytes(
     Yields:
         bytes: Next chunk of file data.
     """
+    read_bytes = 0
     while True:
-        data = file.read(1024 * 1024)  # 1MB
+        if chunk_size is not None and read_bytes >= chunk_size:
+            break
+
+        if isinstance(file, AsyncBufferedReader):
+            data = await file.read(DEFAULT_CHUNK_SIZE)  # 1MB
+        else:
+            data = file.read(DEFAULT_CHUNK_SIZE)  # 1MB
 
         if not data:
             break
 
+        if chunk_size is not None:
+            remaining = chunk_size - read_bytes
+            if remaining <= 0:
+                break
+            if len(data) > remaining:
+                data = data[:remaining]
+            read_bytes += len(data)
+
         # Update the hash function with the data
         hash_func.update(data)