---
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

    Full source code for 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). Help us fix any issues you see by submitting a [Pull Request](https://docs.ultralytics.com/help/contributing/) 🛠️. Thank you 🙏!

---
## ::: ultralytics.utils.loss.VarifocalLoss
<br><br>

---
## ::: ultralytics.utils.loss.FocalLoss
<br><br>

---
## ::: ultralytics.utils.loss.BboxLoss
<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>
