How to use the decimal time and swatch beats converter
- Choose Time to beats or Beats to time.
- Pick the date, then either enter a clock time or a beat count from 0 to 999.99.
- Choose the time zone. The date and time are read in that zone, and for beats the date is the one in Biel.
- Read the beats, the decimal hours and the decimal clock reading, with the local time and the UTC time.
Formula
Beats = seconds since midnight in UTC+1 / 86.4
Decimal hours = seconds since local midnight / 8,640
Decimal clock = 10 hours of 100 minutes of 100 seconds
A beat is one thousandth of a day, or 86.4 seconds. The decimal clock shows local time of day in the same way, so 12:00 is 5:00:00.
Noon in UTC
At 12:00 UTC the time in Biel is 13:00, which is 46,800 seconds after midnight, so the beat count is 46,800 / 86.4 = @541.667. The decimal clock for 12:00 local time is 5:00:00, or 5.0000 decimal hours.
A time of 14:24 is 0.6 of a day, so it reads 6.0000 decimal hours or 6:00:00 on the decimal clock. A time of 20:30 in Tokyo is @520.833, because it is 11:30 UTC and 12:30 in Biel.
Two ways to cut up the day
Swatch Internet Time was launched in 1998 as a single worldwide time with no zones. The day is divided into 1,000 beats, and the reference is Biel Mean Time, which is UTC+1 all year with no daylight saving. Its notation is an at sign and a number, such as @541.667. At a given instant the beat count is the same everywhere in the world.
Decimal time comes from the French Revolution, when the day was briefly split into 10 hours of 100 minutes of 100 seconds. It was meant to match the decimal system used for the rest of measurement. The idea lasted only a short time, but it still shows up in clocks and projects that like the symmetry.
Local time and zones
Beats come from the instant, so a time zone only matters for turning a local clock time into that instant. This tool uses your browser's time zone rules for that, which include daylight saving for the date you choose. A local time that is skipped when the clocks go forward cannot be converted, and the tool tells you so.
The decimal clock is shown for the local time of day in the selected zone, not for UTC, because decimal time was a local clock. Beats and decimal hours are both rounded for display, so a reading may differ in the last digit from another tool.
Assumptions and limits
- Biel Mean Time is UTC+1 throughout the year.
- The decimal clock uses the local time of day in the chosen zone.
- A time inside a daylight saving gap is rejected, and a repeated hour uses the earlier of the two.
- Nothing is uploaded.
Frequently asked questions
Is a beat the same everywhere?
Yes. @500 is the same instant everywhere, and it is noon in Biel, which is 11:00 UTC.
How long is a beat?
86.4 seconds, or 1 minute and 26.4 seconds.
Why does the date for beats refer to Biel?
Beats count through the Biel day, which starts at 23:00 UTC, so the date is the calendar date in UTC+1.
What is a decimal minute?
One hundredth of a decimal hour, or 14.4 normal minutes. A decimal second is 0.864 of a normal second.