---
description: Explore Ultralytics' versatile loss functions - VarifocalLoss, BboxLoss, v8DetectionLoss, v8PoseLoss. Improve your accuracy on YOLO implementations.
keywords: Ultralytics, Loss functions, VarifocalLoss, BboxLoss, v8DetectionLoss, v8PoseLoss, YOLO, Ultralytics Documentation
---

# Reference for `ultralytics/utils/loss.py`

!!! Note

    This file is available at [https://github.com/ultralytics/ultralytics/blob/main/ultralytics/utils/loss.py](https://github.com/ultralytics/ultralytics/blob/main/ultralytics/utils/loss.py). If you spot a problem please help fix it by [contributing](/help/contributing.md) a [Pull Request](https://github.com/ultralytics/ultralytics/edit/main/ultralytics/utils/loss.py) 🛠️. Thank you 🙏!

<br><br>

## ::: ultralytics.utils.loss.VarifocalLoss

<br><br>

## ::: ultralytics.utils.loss.FocalLoss

<br><br>

## ::: ultralytics.utils.loss.BboxLoss

<br><br>

## ::: ultralytics.utils.loss.RotatedBboxLoss

<br><br>

## ::: ultralytics.utils.loss.KeypointLoss

<br><br>

## ::: ultralytics.utils.loss.v8DetectionLoss

<br><br>

## ::: ultralytics.utils.loss.v8SegmentationLoss

<br><br>

## ::: ultralytics.utils.loss.v8PoseLoss

<br><br>

## ::: ultralytics.utils.loss.v8ClassificationLoss

<br><br>

## ::: ultralytics.utils.loss.v8OBBLoss

<br><br>