Bill clients from Google Calendar: rates, rounding and minimums
When your calendar already holds your client work, billing is a matter of rules: which meetings count, at what rate, rounded how, and when a month is final. Writing those rules down once, and applying them the same way every month, is what makes an invoice easy to defend.
Rates: per client, sometimes per project
Most freelancers have one hourly rate per client, and sometimes a different one for a specific project (a workshop billed higher than calls, for example). Keep the rate next to the client, not in your head, and in the client's currency if you bill some clients in dollars and others in euros. When the rate changes, note from which month: invoices already sent should not move.
Rounding: pick one rule and say it
Rounding turns real minutes into billable time. Common rules:
| Rule | Who uses it | A 37-minute call becomes |
|---|---|---|
| Exact time | Anyone billing by the minute | 37 minutes |
| Up to 6 minutes (a tenth of an hour) | Lawyers, many consultants | 42 minutes (0.7 h) |
| Up to 15 minutes | Coaches, trainers, agencies | 45 minutes |
| Up to 30 minutes | On-site work, short interventions | 60 minutes |
Round each meeting, not the monthly total, and write the rule in your quote or contract so the client knows it before the first invoice.
Minimum charge per meeting
A five-minute call still interrupts your day. A minimum, such as 15 or 30 minutes per meeting, covers that. Apply it after rounding: a 5-minute call with 15-minute rounding and a 30-minute minimum bills 30 minutes.
Retainers and prepaid hours
Some clients buy a block of hours: 20 hours a month, or 40 hours to use over a quarter. Track used hours against the block, and warn the client before it runs out. An alert at 80% gives time to top up; one at 100% avoids unpaid work.
What does not count
Decide it once: declined invitations, internal admin, travel (billed or not), all-day events. Mark non-billable time with its own colour or calendar so it never slips into a client total.
Close the month, then invoice
Calendars keep changing: meetings are moved after the fact, cancelled, renamed. Once you invoice a month, freeze its numbers. Edits made later in the calendar should not change an invoice already sent; if something was really wrong, recalculate on purpose and issue a correction.
A statement per client per month should show, for each meeting: date, start and end, title or description, real duration, billed duration and amount. Clients trust a detailed list more than a single number.
Follow payments
Note when each statement was invoiced and when it was paid. Anything unpaid after 30 days deserves a reminder; a list of overdue statements once a month is enough to stay on top of it.
The same rules, applied automatically
Calendar Timesheet applies these rules in your own Google Sheet: a rate and currency per client and per project, rounding up to 5, 6, 10, 15, 30 or 60 minutes, an optional minimum per meeting, prepaid hours with alerts at 80% and 100%, declined and all-day events left out, and months frozen at closing. On the 1st, you get one statement per client and an email with totals and anything unpaid after 30 days.
It is not an invoicing tool: it prepares the numbers and the detail; your invoice is made in your usual software or template.
Try it on your own calendar. The Pro trial lasts until your first month-end statement, 14 days at least. No card.