The 30 Hour System in a day in Japan

Cooking, Japan

Per Kevin

Have you noticed that in Japan there are some signs saying 26:00 hours, 27:00 hours, 28:00 hours? How come the hours in Japan go past 24:00 hours?

Did you know that Japan adopts a counting system for hours that can reach up to 30 hours in some specific contexts? This method is mainly used in sectors such as transportation and nightlife entertainment, where the conventional 24-hour counting is not sufficient.

The counting of hours can continue from midnight, going through 25, 26, up to 30 hours, making it easier to organize activities that extend beyond midnight without confusing it with the beginning of a new day.

What is the 30-Hour System?

Unlike the 24-hour system, which ends the day at midnight (00:00), the 30-hour system extends the "day" until 6 o'clock in the morning of the following day. In this format, midnight is marked as 24:00, and the subsequent hours are counted as 25:00, 26:00, up to 30:00, with it being more common to reach a maximum of 29:00.

This is particularly useful in night services, such as railway transport, where trains can operate until after midnight. Thus, a train that departs at 1 AM in the 24-hour system would be displayed as departing at 25:00 in the 30-hour system.

Practical Applications

This system is widely used in transportation schedules, such as the "Moonlight Nagara" train, which operates at night, with schedules reaching 27:00 (or 3 am). Additionally, signs of nightlife establishments, such as bars and restaurants, often display their closing hours using this counting, indicating that they are open, for example, until 29:00 (5 am).

The 30-hour system in a day in Japan
The 30-hour system in a day in Japan

Differences Between the 24 and 30 Hour Systems

The main difference between the 24 and 30-hour systems is how the "new day" is treated. In the 24-hour system, the day officially changes at midnight, or 00:00. However, in the 30-hour system, the "new day" only starts at 6 AM. Thus, the hours between midnight and 6 AM are still part of the "previous day." For example:

  • 24:00 in the 30-hour system corresponds to 00:00 in the 24-hour system;
  • 25:00 equals 1 a.m. in the 24-hour system;
  • 30:00 is equivalent to 6 am the next day.

Example of Comparison

  • January 3, 06:00 = January 2, 30:00 in the 30-hour system;
  • January 3, 12:00 = January 3, 12:00 in the 24-hour system;
  • January 4, 00:00 = January 3, 24:00 in the 30-hour system.
The 30-hour system in a day in Japan

Where is the System Used?

The 30-hour system is applied in various areas in Japan:

  1. TransportThe train operators, like JR, use this counting to indicate the schedules of night trains. This allows for better organization without confusing passengers about the day of operation.
  2. Entertainment: Bares, clubes e outros estabelecimentos que operam durante a madrugada também usam esse sistema para indicar seus horários de funcionamento até a manhã seguinte.
  3. Programas de Televisão e Animes: Os estrangeiros que procuram horário de exibição de programas na TV Japonesa acaba se assustando ao ver que um anime vai passar as 28:00.
  4. Astronomy: O sistema de 30 horas também é utilizado em observações astronômicas, onde a continuidade temporal é crucial para evitar erros de comunicação durante longas sessões de observação​.

Final Thoughts

Embora o sistema de 30 horas seja amplamente utilizado em setores específicos no Japão, ele pode ser confuso para quem não está familiarizado com essa prática. Ainda assim, sua adoção simplifica a operação de serviços noturnos e facilita a vida de quem trabalha ou se desloca durante a madrugada. Se você estiver no Japão, fique atento aos letreiros e horários que podem apresentar esse formato estendido – uma curiosidade fascinante do cotidiano japonês!

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