A day hire is charged in 24-hour periods from pick-up. Pick up at 10am Friday and return at 10am Monday: three days. A return a little late does not start another day until it runs past the grace - 59 minutes unless you change it in Settings → Renting → Days and times. The same count prices the booking page's quote, the contract, a change of dates or times, an extension and the late-return line when the car comes back, and it is counted on your local clock, so a daylight-saving change does not add or lose a day.
Tip: A booking keeps the count it was made with. Changing the grace changes it for bookings made from then on, never for one already made. Weekly and open-ended hires are billed in their payment cycles and are not affected.
The gap between hires
Gap between hires keeps a car free for that long after each return, so it can be checked and cleaned before the next renter collects it - two hours unless you change it. Your booking page, your own new contracts and the calendar all leave the gap when both the return and pick-up times are known.
Notice and depot hours
Booking page notice is the earliest a booking-page request may start from now. Give each pick-up and return location its opening hours in Settings → Renting → Pick-up & return locations, and the booking page offers only times when that depot is open; a request outside them is refused. A location with no hours set takes any time. Your own contracts are never held to the notice or the hours, so a walk-in or a backdated booking still works.
After-hours key drops
A renter returning out of hours can tap I've dropped the car off in their portal, or you can tick Key drop when you record the return. Either way the hire counts as returned at the drop time: no more reminders or overdue emails, and the return wizard starts from that time rather than now, so any late day is counted to the drop. Inspect the car and record the return as usual - nothing is settled until you do.
Needs cleaning
Answering Needs cleaning or a check at the end of a return holds the car for the rest of that day. It is bookable again from the next day; delete the hold on the calendar to free it sooner.