Open Steam and log in to your account
Click your profile name in the top-right corner
Select Account details
Scroll to Store and Purchase History
Click View purchase history
Check your individual purchases and add them up manually
For a more complete total, use Steam Support’s external calculator tools if available
To see wallet spending, check Wallet history in Account details
To see all account spending, include game purchases, DLC, in-game purchases, and wallet top-ups
If needed, contact Steam Support for account spending information