Duration, buffers and slot times
How long an appointment takes, the gap after it, and why times appear where they do.
Three settings decide when a customer can start an appointment: how long the service runs, how much protected time follows it, and the grid every start time sits on. Two live on the service; the third is site-wide.
Duration: the length of one appointment
Duration lives on the General tab of any service, at Booked › Business › Services. It is a whole number of minutes, and a new service starts at 30. It sets the length of the block drawn in your Calendar, and how much clear time a slot must find before that start time can be offered.
On the customer's service card it is written the way people speak — "45 min" under an hour, then "1h 30m" or "2h".
The box accepts 1, but when Booked works out which times to offer, anything under five minutes is treated as five.
If the service allows Group bookings, party size multiplies the duration. Three people on a 20-minute service is one 60-minute appointment with one member of staff — not three running side by side. That is why times can disappear when a customer adds a second person.
Buffers: only one of them reserves time
The same tab holds two more boxes. They look like a matching pair. They are not.
Services
The General tab of a service — duration (1) and the two buffer boxes (2, 3).
- 1Duration (minutes) — how long one appointment runs, and the length the customer is quoted.
- 2Buffer before (min) — saved and shown back to you, but never used. It has no effect on which times are offered.
- 3Buffer after (min) — the one that does the work. It is added to the duration, so a slot must find duration plus buffer of clear time.
If you need ten minutes to clean the room before an appointment, typing 10 into Buffer before (min) changes nothing. Add it to Buffer after (min) instead, or lengthen the duration.
The buffer is not written into the saved appointment's end time — the Calendar block still shows 30 minutes, not 40. What it does is make Booked look for 40 clear minutes running forward from the start time before it will offer that time at all. So it protects the run-up to your next booking, but a customer can still take a slot starting the exact minute an existing appointment finishes. Two 30-minute appointments with a 10-minute buffer can end up genuinely back to back.
The time slot interval sets the start grid
Duration and buffer decide how much room an appointment needs. The Time slot interval decides where it may begin. It lives at Booked › Settings › Booking rules, in the Booking rules card.
Configure how Booked works.
Settings › Booking rules (1), where the Time slot interval (2) is set for the whole site.
- 1The Bookings tab — rules that apply to every booking, whatever the service.
- 2Time slot interval — 5, 10, 15, 20 or 30 minutes, or 1 hour. The default is 15. It changes only where an appointment can start, never how long it is.
Two details catch people out. Start times are stepped from the beginning of each open period, not from the clock — a branch opening at 09:10 on a 15-minute interval offers 09:10, 09:25, 09:40, not 09:15. And the whole block must fit inside one continuous open period, so an appointment can never straddle a lunchtime close or run past closing time.
Worked example: a morning ear-care clinic
Priya runs ear syringing at the Bramhall branch on Tuesday mornings, 09:00 to 13:00. The service is 30 minutes with a 10-minute buffer after, on the default 15-minute interval.
A 30-minute service with a 10-minute buffer, on a 15-minute grid, in a 09:00–13:00 clinic.
- 1The open period — where the branch is open and Priya is working. Every block must sit entirely inside it.
- 2The block — 30 minutes of appointment plus 10 minutes of buffer. Booked needs 40 clear minutes before it offers a start time.
- 3The last start of the morning — 12:15. A 12:30 start would need until 13:10, and the clinic closes at 13:00.
- 4What the customer is offered — every quarter hour from 09:00 to 12:15. 12:30 and 12:45 never appear.
Notice what the buffer costs. Without it, a 12:30 start would finish exactly at 13:00 and be offered. With it, 12:30 would need until 13:10, so it disappears — and because starts only exist on the quarter hour, the last bookable time drops back to 12:15. You lose a whole appointment off the end of the morning, not ten minutes. That is the price of protecting your turnaround.
Matching the interval to your durations
The interval is one setting for the whole site, so it needs to suit your commonest appointment length. When a duration is not a multiple of the interval, dead gaps open between back-to-back bookings.
| Duration | Interval | What happens |
|---|---|---|
| 30 min | 15 minutes | Appointments sit flush against each other. Nothing wasted. |
| 45 min | 15 minutes | Also clean — 45 divides by 15. |
| 20 min | 15 minutes | 09:00–09:20 is booked, and the next offerable start is 09:30. Ten minutes of every cycle is unusable. |
| 20 min | 20 minutes | The same service, back to back all day, with no gaps. |
| 10 min | 1 hour | One start an hour. Fifty minutes idle between appointments. |
A 5-minute interval gives the most choice and packs the day tightest, but produces ragged times like 09:35. A long interval keeps the diary tidy at the cost of bookable time.
Changing Time slot interval moves the start times for every service, branch and member of staff, on the booking form and in the admin. Existing bookings keep their old times, so change it when the diary is quiet.
If the times aren't where you expect
- The last slot of the day is earlier than you thought. That is Buffer after (min) pulling the last start back so the whole block still fits before you close.
- Times start at odd minutes, like 09:10. The grid counts from the start of your open period, not from the hour. Check the branch opening hours and the staff working hours.
- There is a hole between every appointment. Your duration is not a multiple of the interval. Change one so they divide evenly.
- Times vanished when the customer added a person. Group bookings multiply the duration, so three people on a 20-minute service need a clear hour.
- You changed "Buffer before (min)" and nothing happened. It does nothing. Move the minutes to Buffer after (min).
- No times at all on a day. This is rarely duration or buffers. Check the branch has opening hours, someone is working, and a member of staff is linked to both the service and that branch.
Finally, Booked has no minimum notice period. Past times drop off today's list automatically, but nothing stops a customer booking a slot minutes from now. If you need lead time, build it into your opening or working hours.