# What is the Lookback Period?

The lookback period is a critical parameter when creating custom commitment plans in Archera. It determines how far back in your usage history Archera looks when calculating recommendations.

## Why the Lookback Period Matters

If your organization experiences temporary usage spikes or drops (for example, a recent spike in temporary usage or a drop during a weekend), the default commitment plans could be skewed by these recent fluctuations. By adjusting the lookback period to a longer timeframe, you get recommendations that are more robust to these temporary variations.

## How to Set the Lookback Period

1. Navigate to the **Commitment Planner** from the left-hand navigation pane
2. Click the purple **"Create Custom Plan"** button on the right-hand side of the page
3. Select the **"Top Down"** plan option from the menu

## Adjusting the Lookback Period

By default, the commitment planner has a lookback period of **7 days**. To lengthen this period:

1. Click on **"Different Range"** at the bottom right of the configuration menu
2. Use the slider provided to select your desired date range
3. Typical examples include 30, 60, or 90 days

## Completing Your Plan

Once you've set your preferred lookback period:

1. Configure any other desired options for your commitment plan
2. Click **"Submit"**
3. Wait for the plan to calculate

## Benefits of Longer Lookback Periods

Setting a longer lookback period allows Archera to acquire a better usage baseline to cover with the recommended commitments. This results in more accurate and reliable recommendations for your cloud infrastructure needs.

## Related Resources

* [Commitment Planner - Overview](https://docs.archera.ai/help-center/user-guide/commitment-planner)
* [How to Create a Custom Purchase or Renewal Plan](https://docs.archera.ai/help-center/user-guide/how-to-create-custom-plan)
* [How Does Archera Calculate Commitment Coverage](https://docs.archera.ai/help-center/user-guide/commitment-coverage)