How do I convert an estimate to an invoice?

To convert an estimate to an invoice:

Go to the Sales module on the left sidebar.
Select Estimates
Select the the estimate you want to convert to an invoice.
Click on Convert to Invoice button on the tor right corner of the page.
Check the required details, and make any changes you want to the estimate, before saving it as an invoice.
Select Save as draft if you want to keep the invoice in the balance for now, click Save and Send if you want the invoice to be sent out immediately.