diff --git a/litgpt/utils.py b/litgpt/utils.py
index ec79fa0764..fa0113e16c 100644
--- a/litgpt/utils.py
+++ b/litgpt/utils.py
@@ -568,7 +568,7 @@ def choose_logger(
     log_args: dict | None = None,
     resume: bool | None = None,
     **kwargs: Any,
-):
+) -> Any:
     if logger_name == "csv":
         return CSVLogger(root_dir=(out_dir / "logs"), name="csv", flush_logs_every_n_steps=log_interval, **kwargs)
     if logger_name == "tensorboard":
@@ -607,7 +607,7 @@ def choose_logger(
     )
 
 
-def get_argument_names(cls):
+def get_argument_names(cls: type) -> set[str]:
     sig = inspect.signature(cls.__init__)
     return {
         name
@@ -616,7 +616,7 @@ def get_argument_names(cls):
     }
 
 
-def instantiate_bnb_optimizer(optimizer, model_parameters):
+def instantiate_bnb_optimizer(optimizer: str | dict, model_parameters: Any) -> Any:
     if (isinstance(optimizer, str) and "AdamW" not in optimizer) or (
         isinstance(optimizer, dict) and "AdamW" not in optimizer.get("class_path", "")
     ):
@@ -633,7 +633,7 @@ def instantiate_bnb_optimizer(optimizer, model_parameters):
     return optimizer
 
 
-def instantiate_torch_optimizer(optimizer, model_parameters, **kwargs):
+def instantiate_torch_optimizer(optimizer: str | dict, model_parameters: Any, **kwargs: Any) -> torch.optim.Optimizer:
     # Special care taken where some optimizers do not have some parameters referenced in some of the code, for example "fused" in the pretrain.py script:
     #   bnb.optim.AdamW8bit
     #   grokadamw.GrokAdamW
@@ -679,7 +679,9 @@ def extend_checkpoint_dir(checkpoint_dir: Path) -> Path:
     return new_checkpoint_dir if should_return_new_dir else checkpoint_dir
 
 
-def check_file_size_on_cpu_and_warn(checkpoint_path, device, size_limit=4_509_715_660):
+def check_file_size_on_cpu_and_warn(
+    checkpoint_path: Path | str, device: torch.device | str, size_limit: int = 4_509_715_660
+) -> float:
     """
     Checks the file size and raises a warning if it exceeds the size_limit.
     The default size limit is 4.2 GB, the size of TinyLlama 1.1B: 4.2 * 1024 * 1024 * 1024 = 4_509_715_660
@@ -695,7 +697,9 @@ def check_file_size_on_cpu_and_warn(checkpoint_path, device, size_limit=4_509_71
     return size
 
 
-def auto_download_checkpoint(model_name, access_token=None, ignore_tokenizer_files=False):
+def auto_download_checkpoint(
+    model_name: str, access_token: str | None = None, ignore_tokenizer_files: bool = False
+) -> Path:
     from litgpt.scripts.download import download_from_hub  # moved here due to circular import issue
 
     checkpoint_dir = extend_checkpoint_dir(Path(model_name))
@@ -716,7 +720,7 @@ def auto_download_checkpoint(model_name, access_token=None, ignore_tokenizer_fil
     return checkpoint_dir
 
 
-def check_nvlink_connectivity(fabric=None):
+def check_nvlink_connectivity(fabric: L.Fabric | None = None) -> None:
     """Checks GPU connectivity for both NVIDIA and AMD GPUs.
 
     This function delegates to vendor-specific implementations based on
@@ -744,7 +748,7 @@ def check_nvlink_connectivity(fabric=None):
             custom_print(f"An error occurred while checking GPU connectivity: {e}")
 
 
-def _check_nvidia_connectivity(custom_print):
+def _check_nvidia_connectivity(custom_print: Any) -> None:
     """Checks NVLink connectivity on NVIDIA GPUs."""
     result = subprocess.run(["nvidia-smi", "topo", "-m"], stdout=subprocess.PIPE, text=True)
     if result.returncode != 0:
@@ -779,7 +783,7 @@ def _check_nvidia_connectivity(custom_print):
         )
 
 
-def _check_amd_connectivity(custom_print):
+def _check_amd_connectivity(custom_print: Any) -> None:
     """Checks XGMI connectivity on AMD GPUs."""
     result = subprocess.run(["rocm-smi", "--showtopotype"], stdout=subprocess.PIPE, text=True)
     if result.returncode != 0:
@@ -825,7 +829,7 @@ def _check_amd_connectivity(custom_print):
         )
 
 
-def fix_and_load_json(s):
+def fix_and_load_json(s: str) -> Any:
     # Remove trailing commas before } or ]
     s = re.sub(r",(\s*[}\]])", r"\1", s)
 
@@ -842,7 +846,7 @@ def fix_and_load_json(s):
         raise ValueError(f"Failed to parse JSON after fixing: {e}")
 
 
-def create_finetuning_performance_report(training_time, token_counts, device_type):
+def create_finetuning_performance_report(training_time: float, token_counts: dict[str, int], device_type: str) -> str:
     tok_sec = token_counts["raw_tokens_plus_prompt_template_and_padding"] / training_time
     output = f"""
 | ------------------------------------------------------
@@ -866,7 +870,7 @@ def create_finetuning_performance_report(training_time, token_counts, device_typ
     return output
 
 
-def select_sft_generate_example(eval, data):
+def select_sft_generate_example(eval: Any, data: Any) -> str:
     if eval.evaluate_example == "first":
         if len(data.test_dataset.data):
             instruction = data.test_dataset.data[0]["instruction"]
@@ -895,7 +899,7 @@ def select_sft_generate_example(eval, data):
     return instruction
 
 
-def _RunIf(thunder: bool = False, **kwargs):
+def _RunIf(thunder: bool = False, **kwargs: Any) -> Any:
     import pytest
     from lightning.fabric.utilities.testing import _runif_reasons
 
@@ -908,7 +912,7 @@ def _RunIf(thunder: bool = False, **kwargs):
     return pytest.mark.skipif(condition=len(reasons) > 0, reason=f"Requires: [{' + '.join(reasons)}]", **marker_kwargs)
 
 
-def kill_process_tree(pid: int):
+def kill_process_tree(pid: int) -> None:
     """
     Kill a process and all its child processes given the parent PID.
     """