diff --git a/comfy/model_patcher.py b/comfy/model_patcher.py
index 5b1ccb824..62c4f291f 100644
--- a/comfy/model_patcher.py
+++ b/comfy/model_patcher.py
@@ -35,6 +35,7 @@ import comfy.model_management
 import comfy.patcher_extension
 import comfy.utils
 from comfy.comfy_types import UnetWrapperFunction
+from comfy.quant_ops import QuantizedTensor
 from comfy.patcher_extension import CallbacksMP, PatcherInjection, WrappersMP
 
 
@@ -662,12 +663,18 @@ class ModelPatcher:
                 module_mem = comfy.model_management.module_size(m)
                 module_offload_mem = module_mem
                 if hasattr(m, "comfy_cast_weights"):
-                    weight_key = "{}.weight".format(n)
-                    bias_key = "{}.bias".format(n)
-                    if weight_key in self.patches:
-                        module_offload_mem += low_vram_patch_estimate_vram(self.model, weight_key)
-                    if bias_key in self.patches:
-                        module_offload_mem += low_vram_patch_estimate_vram(self.model, bias_key)
+                    def check_module_offload_mem(key):
+                        if key in self.patches:
+                            return low_vram_patch_estimate_vram(self.model, key)
+                        model_dtype = getattr(self.model, "manual_cast_dtype", None)
+                        weight, _, _ = get_key_weight(self.model, key)
+                        if model_dtype is None or weight is None:
+                            return 0
+                        if (weight.dtype != model_dtype or isinstance(weight, QuantizedTensor)):
+                            return weight.numel() * model_dtype.itemsize
+                        return 0
+                    module_offload_mem += check_module_offload_mem("{}.weight".format(n))
+                    module_offload_mem += check_module_offload_mem("{}.bias".format(n))
                 loading.append((module_offload_mem, module_mem, n, m, params))
         return loading