Time in My Time at Portia is measured in hours and minutes that are relative to real-world time, with one minute in Portia equaling slightly less than one second in real time. At the default game speed, a single uninterrupted in-game day is a minimum of 15 real-world minutes.
Time is essential to gameplay. On a daily basis, it defines the phase of day, how long an item takes to be crafted, NPC schedules, business and home visiting hours, and more. Additionally, commissions typically have deadlines, crops are seasonal, and certain events only happen on certain days of the week, so it is beneficial to be aware of the calendar and other time-related information.
Time pauses while in a menu and while visiting the Hazardous Ruins.
Game time is measured in the 24-hour clock, meaning that 1:00 pm is displayed as 13:00, 11:59 pm is 23:59, and midnight is 00:00.
The player awakens at 7:00 and is able to stay up until 3:00 in the morning. Hours between 3:00 and 7:00 are inaccessible. If 3:00 passes before the player goes to sleep, then the player will pass out and wake up in bed at 7:00 (or be teleported to their home if they do not have a bed placed there). There are no penalties for passing out at 3:00. If the player wishes to avoid passing out, it is advised that if one is working far from one's home, they should get to the nearest Dee-Dee Stop and/or ride a mount to get to bed on time.
The Dee-Dee Transport System runs from 7:00-0:00.
The speed of time's passage can be set anywhere between 100% (default rate) and 50% (half rate), which forces time to move at a slower rate and allows the player more time to play the game at their pace. This setting can be manually changed via the options menu at any point in the game that the menu is accessible. All time-related events move at the rate applied in the settings; the pace at which an NPC travels from one point to another is not affected, allowing NPCs to arrive at their destination earlier on slower speeds.
Time passes as long as the player idles in the overworld. Time only stops when opening an interface (such as a menu, the Inventory, or shop menus), speaking to an NPC, or entering any Hazardous Ruins (including those encountered only during missions) or the Haunted Cave. Entering the Sewage Plant, Ingall's Mine, Deepest Ruin, or Haunted Cave will consume a set amount of time upon entry, though time is completely frozen while inside.
Going to bed can pass time to the next day. Regardless of time of day, the player can sleep in bed until the next morning at 7:00. Taking the Dee-Dee Transport passes time due to the player traveling to a different location, off-screen. Depending on the location, the amount of time to travel from point A to point B varies; the further the distance, the more time is passed. Going to bed or taking the Dee-Dee Transport are the only methods of quickly passing time.