When creating an invoice, you can charge by the hour. Here is the best way to do it.
Go to Settings > Templates > New Item.
Create an invoice item for 1 hour's worth of work. Set your price, and write a description. The duration is optional, leaving this blank won't affect anything.
After you finish, press 'Add'.
Next, select the project you wish to send an invoice to. If you haven't created one yet, go to the projects tab and select 'Create Project'.
Click 'Add Invoice'. Add the item you just created for 1 hour's worth of work.
In the invoice there is a place for item quantity, here you can enter the number of hours and the invoice will calculate the total amount.
Set what payment types you accept, whether or not you want to charge a retainer, the tax rate, discount amount, due date, and charge method.
After this, save the invoice. You will be prompted to send the invoice.
You may preview the invoice by pressing 'View and send invoice', and going to the invoice URL.
You can share this URL with your client, or send it in an email through Bloom.
After previewing your invoice and making sure everything is accurate you're ready to send the invoice to your client.