The basics of date and time localization

How do people prefer to read date and time? In the format they’re used to, of course! But with nearly 200 countries in the world today, you can bet there will be plenty of different formats too. This is why you need to add date and time localization to your workflow if you wish to enter new markets successfully.

The role of formats in global software development

When developing applications, software engineers and designers need to account for localization to ensure that users across the globe can interact with the product naturally. This is especially important for applications that handle scheduling, booking, or event management.

Here are some tools and libraries to check out when localizing formats:

• Moment.js (JavaScript)
• Intl API (JavaScript)
• Babel (Python)
• CLDR (Unicode Common Locale Data Repository)

The ISO 8601 standard

There is a standard when it comes to displaying date and time, and that’s ISO 8601. It is maintained by the International Organization for Standardization (ISO) and is widely used across industries, especially in contexts where precise, uniform date and time information is needed, such as databases, data exchange, scheduling systems, and APIs.

ISO 8601 defines aspects like:

• Date formats: YYYYMMDD (basic format) and YYYY-MM-DD (extended format)
• Time format: hhmmss (basic format) and hh:mm:ss (extended format)
• Date and time combination: YYYYMMDDThhmmss (basic format) and YYYY-MM-DDThh:mm:ss (extended format)
• Week dates: YYYY-Www-D
• … as well as durations, intervals, symbols, and more of which you can read about here.

Date formats around the world

Some of the common date formats recognized across the globe are:

• DD/MM/YYYY. This is probably the most used format, and it’s being used in many countries in Europe, Asia, Africa, and Latin America. For example, “01/02/2025” would be the 1st of February, 2025.
• MM/DD/YYYY. You’ll encounter this format in the United States and a few other countries like Canada and the Philippines. Here, “02/01/2025” would be February 1, 2025.
• YYYY/MM/DD. This format is standardized by ISO 8601 and used in places like China, Japan, Korea, and for technical purposes worldwide (e.g., databases, APIs). An example would be “2025/02/01.”

Date separators

Yes, even the date separators require localization. You have the following options:

• Slash (/). This is common in most English-speaking countries (e.g., “01/02/2025”).
• Dash (–). Often seen in technical or international contexts (e.g., “2025-02-01” following ISO 8601).
• Periods (.). These are used in countries like Germany or Hungary (e.g., “01.02.2025”).

Text-based formats

Some regions will simply write the date in full text, but this varies too:

• In the United States, you’ll see the date written as “February 1, 2025.”
• In the United Kingdom, it would be “1 February 2025.”
• In Japan, you’ll see a kanji after each element, so you’d have “”2025年2月1日” (where 年 means “year,” 月 means “month,” and 日 means “day”).

Note that localized text formats may include ordinal numbers (e.g., 1st, 2nd, 3rd, 4th) or require specific translations for month names, depending on the language and region.

Time formats around the world

Here we have two time formats:

• 12-hour format, which is used in countries such as the U.S., Canada, and the Philippines. The day is split into two 12-hour periods, using AM (Ante Meridiem) and PM (Post Meridiem) to differentiate between morning and afternoon. In these regions, “2:30 PM” means 2:30 in the afternoon.
• 24-hour format, which is used in most European, Latin American, and Asian countries. This format is also popular in military, scientific, and technical settings worldwide. The 24-hour format avoids the need for AM/PM indicators, making it unambiguous. Here, “14:30” refers to 2:30 PM.

Other cultural preferences come into play too. In India, it’s common to write time without the colon (14.30), whereas, in other countries, time is separated by a colon (14:30). This small difference can affect how people perceive the time format, even if the overall system is the same.

Time zones

Wait, that’s not all. Time zones introduce further complexity:

• UTC offset. Many systems display time with the offset from Coordinated Universal Time (UTC), such as “14:30 UTC+2” (2 hours ahead of UTC).
• Named time zones. Sometimes, names of time zones like “Eastern Standard Time (EST)” or “Pacific Daylight Time (PDT)” are shown instead. However, users in different regions might not be familiar with foreign time zone names, so localization ensures appropriate conversions.

First day of the week

Another aspect of date and time localization is the first day of the week, an element that affects calendars, scheduling apps, and date pickers.

• Monday as the first day is a format used in most of Europe, Asia, and Africa. For example, in the European Union and ISO standards, Monday is considered the first day of the week.
• Sunday as the first day is typical in the United States, Canada, and many Middle Eastern countries like Saudi Arabia.
• Saturday as the first day can be observed in much of the Middle East and North Africa due to the Islamic influence.

Localizing language-specific elements

Localization of date and time requires adapting both the structure and the language used for days of the week, months, and time indicators (like AM/PM). Month and day names, as well as the days of the week, must be translated to the user’s language too.

To conclude

Reading date and time in a format you’re not used to can be very confusing and can ruin one’s experience with a website or app. Date and time localization can prevent any confusion and keep your users happy. All you need to do is change the formats to match local conventions or leverage standards like ISO 8601. Now that you know how important it is to adapt letters, numbers, and date and time separators, it’s time to get things going with the help of your trusty translation management system.