---
title: Weights and Biases
description: >-
  Weights & Biases (W&B)  allows machine learning practitioners to track
  experiments, visualize data, and share insights with a few lines of code.
canonical: 'https://lightning.ai/docs/fabric/stable/reference/guide/loggers/wandb'
---
# Weights and Biases {#weights-and-biases}

[Weights & Biases (W&B)](https://wandb.ai)  allows machine learning practitioners to track experiments, visualize data, and share insights with a few lines of code.

It integrates seamlessly with your Lightning ML workflows to log metrics, output visualizations, and manage artifacts.
This integration provides a simple way to log metrics and artifacts from your Fabric training loop to W&B via the `WandbLogger`.
The `WandbLogger` also supports all features of the Weights and Biases library, such as logging rich media (image, audio, video), artifacts, hyperparameters, tables, custom visualizations, and more.
[Check the official documentation here](https://docs.wandb.ai).

## Set Up Weights and Biases {#set-up-weights-and-biases}

First, you need to install the `wandb` package:

```bash
pip install wandb
```

Then log in with your API key found in your W&B account settings:

```bash
wandb login <your-api-key>
```

You are all set and can start logging your metrics to Weights and Biases.

## Track metrics {#track-metrics}

To start tracking metrics in your training loop, import the WandbLogger and configure it with your settings:

```python
from lightning.fabric import Fabric

# 1. Import the WandbLogger
from wandb.integration.lightning.fabric import WandbLogger

# 2. Configure the logger
logger = WandbLogger(project="my-project")

# 3. Pass it to Fabric
fabric = Fabric(loggers=logger)
```

Next, add `log` calls in your code.

```python
value = ...  # Python scalar or tensor scalar
fabric.log("some_value", value)
```

To log multiple metrics at once, use `log_dict`:

```python
values = {"loss": loss, "acc": acc, "other": other}
fabric.log_dict(values)
```

## Logging media, artifacts, hyperparameters and more {#logging-media-artifacts-hyperparameters-and-more}

With `WandbLogger` you can also log images, text, tables, checkpoints, hyperparameters and more.
For a description of all features, check out the official Weights and Biases documentation and examples.

- [Official WandbLogger Lightning and Fabric Documentation](https://docs.wandb.ai/guides/integrations/lightning) — Learn about all features from Weights and Biases

- [Fabric WandbLogger Example](https://colab.research.google.com/github/wandb/examples/blob/master/colabs/pytorch-lightning/Track_PyTorch_Lightning_with_Fabric_and_Wandb.ipynb) — Official example of how to use the WandbLogger with Fabric

- [Lightning WandbLogger Example](/docs/fabric/2.6.6/reference/guide/loggers/wandb.me/lightning.md) — Official example of how to use the WandbLogger with Lightning

---

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