Timesheets
··· → Print & export → Timesheet. A week (a column per day) or a month (a column per week) of the hours you logged, by project, then every event with its hours. Pick one project or all, and tick Count planned hours to include events with no actual hours yet. Export CSV, or print it or save it as a PDF.
Invoice from Hours
··· → Print & export → Invoice from hours (or Make an invoice in the timesheet). Choose the dates and project, your rate per hour, the currency (pounds by default) and whether to add VAT. Fill in your details, the client and payment details once - Calendar remembers them, and the next invoice number. Print it, or choose Microsoft Print to PDF to save it.
Where the Hours Come From
Edit an event and fill in Actual duration (hrs). Planned hours come from the event's start and end times.