24-Hour Time Zone Converter

Why 24-hour time exists

The 24-hour clock was standardised in France in the 1790s and became the norm for railways, the military and, later, aviation. Its purpose is simple: a day has 24 hours, so counting from 00:00 to 23:59 needs no extra half-day marker, no "midnight ambiguity" and no linguistic suffix.

It is now the default in most of the world. Germany, France, Spain, Italy, Japan, South Korea, China, Singapore, Australia, Brazil and Russia all use 24-hour time in everyday life, in timetables and in conversation. The United States, Canada, the UK, Australia's neighbours and India are the main hold-outs.

For anything technical it is already mandatory: ISO 8601 timestamps, log files, flight itineraries, train schedules, medical dosing charts and military reporting all use the 24-hour form. UTC is expressed in 24-hour notation, which is another reason "UTC time" and "24-hour time" travel together.

How to read a 24-hour clock

Midnight is written 00:00 and noon is written 12:00, so the day runs 00:00, 00:30, 01:00 … up to 23:59. Hours 00:00–11:59 are the morning, 12:00–17:59 the afternoon and 18:00–23:59 the evening. Minutes always come first in speech: 09:45 is "nine forty-five", never "nine and three quarters".

One special case worth knowing: in aviation, maritime and military contexts the four-digit form without a colon — 0930, 1745 — means UTC and is often read aloud as "zero nine thirty" and "seventeen forty-five". The Z suffix in "2026-03-14T09:30:00Z" means the same thing.

• 00:00 = midnight, the start of the day
• 12:00 = noon, the middle of the day
• 13:00 = 1 pm · 18:00 = 6 pm · 23:59 = 11:59 pm
• 23:00 + 1 hour = 00:00 the next day
• 00:30 on the 14th in Tokyo = 15:30 on the 13th in Los Angeles (previous day)

Switching the converter into 24-hour mode

The converter has a 12h / 24h toggle in the toolbar, next to the date controls. Switch it once and every clock on the timeline, every planner suggestion and every table on the page switches to 24-hour notation at the same time.

The preference is stored in your browser, and it can also be set from a link — adding "&f=24" to any converter URL opens the page already in 24-hour mode. That makes it easy to send a colleague a link that matches how they think.

The 24-hour world clock

The timeline is the core of the tool: one column per hour of the day, one row per city, and the reference city's hours across the top. Because every column is a full 24-hour cycle rather than a morning-to-evening window, you see the entire day — including the hours that are 3 a.m. for someone — instead of a cropped view.

Hovering or tapping a column selects that instant everywhere at once, and the summary underneath spells it out in words: "It is 09:00 in London, 04:00 in New York and 17:00 in Singapore." That is the fastest way to answer a timezone question without mental arithmetic.