Hi,

In Odoo, when the unit of measure is set to Days, the system counts both the check-in and check-out days as billable, which leads to an extra day being included in the cost calculation. This is standard behavior because Odoo assumes day-based rentals or bookings work on a calendar-day basis. To handle this, the simplest solution is to keep the unit of measure as Hours and restrict bookings to multiples of 24 hours so that pricing remains accurate while still reflecting full-day usage. Alternatively, you could customize the calculation logic to exclude the last day from the count or adjust pricing rules to compensate. Using hours with a restriction to full days is often the cleanest and most reliable option since it avoids altering Odoo’s default behavior while ensuring correct cost and duration calculations.

Hope it helps