You can now access detailed Google billing information to get better understanding of:
What is the cost per project per month/ per day/ before and after credits
Which GCP product or project costs the most
What’s the trend for your GCP costs
Cloud Billing reports will help you quickly answer the above questions, provide charts about usage or discover and analyze trends.
To access reports, go to Billing section from the main menu and select Reports.
Watch this Youtube video with details about Billing Reports.