24 hour

Designing for the 24 hour dial, and for the Apple Watch

In a fascinating article, Alex Komarov shares the design process that went into the development of his iPhone (and potential Apple Watch) app called “24 Hours”, a combined time zone calculator and 24 hour clock.


The app is available on the App store now, priced between 1 and 2 dollars/pounds/euros.

The problem:

our team and our clients are distributed across five continents. We have to deal with a half-dozen time zones on a daily basis, which can be a nightmarish experience: calls in the middle of the night, frustration, missed deadlines, broken communication, lost opportunities.

The solution (obvious, of course, to frequent visitors to this site):

We decided that using a 24 hour face is a fair trade-off: it’s not as familiar as a 12-hour clock face. People would have to get used to it, but they’d have a much easier way of telling and converting times once they do. We decided this was a fair trade-off.

The resulting app works well and looks good.

As for their Apple Watch app, it was rejected, because Apple don’t currently allow third-party watch faces:

Long story short: after a bunch of back and forth with the review team we decided to put Apple Watch version of our app on hold and released iOS-only version for the time being.

Although most of the built-in watch displays on the Apple Watch are either digital or analog 12-hour, there is in fact one 24 hour time display built-in — it’s the setting dial for the alarm clock:

IMG 0722

It’s a well-known problem with the 12 hour dial that setting an alarm can be confusing and error-prone, particularly if you’re trying to set an alarm for a time more than 12 hours in the future.


Tauba Auerbach – The Thing Quarterly: currently on sale on eBay

On eBay at the moment:

A wonderful limited edition 24 hour clock from TAUBA AUERBACH created for issue 20 of THE THING QUARTERLY way back in 2013.  Known for her stunning typography and print works this 10.5inch diameter takes on an analogue timepiece with a 24 hour version running from midnight to midnight.  The clock features black hour and minutes hands and gold-hued numerals in AUERBACH’s graphic style.  The clock can be hung with the built-in hook and needs just one AA battery to get up and running. In excellent condition, the clock also comes in a stunning bespoke box from an edition of 1500. 

$ 57

The Berlin Set Theory Clock

berlin-set-theory-clock or 09:54?

This clock has been mentioned in the news recently. It’s the Set Theory Clock, also known as the Berlin Clock. There’s an excellent description — and a working version — at 3Quarks:Berlin Clock. It consists of 24 lights (and a 25th one on the top which flashes every second).

From the description at 3Quarks:

It makes use of the principle of set theory to depict the time. The time of day is displayed in a 24-hour format and can be determined by simply adding and multiplying the glowing lights.
The first, uppermost row consists of 4 red lights, whereby each of these lights stands for 5 full hours. The 4 red lights in the second row display one full hour apiece. For example, if the first 2 lights in the uppermost row and all 4 lights in the second row are lit up, that represents 1400 hours, or 2 p.m. (2 × 5 + 4 hours).

The third row is composed of 11 lights: 3 red and 8 yellow. Each light in this row stands for 5 elapsed minutes. The 3 red lights have been assigned to mark the quarters of an hour and are intended to make reading the clock easier. Last of all, the yellow row at the very bottom displays units of single minutes.

The working version can be found at 3Quarks – Set Theory Clock.

The original version was installed in 1975:

Dieter Binninger, an inventor and tinkerer from Berlin who is also a trained clockmaker, designed the Set Theory Clock on behalf of the Berlin Senate in 1975. The clock was installed on Kurfürstendamm in the Berlin-Charlottenburg district and rapidly evolved into a tourist attraction, though it turned out to have one serious disadvantage: its inner workings consisted of hundreds of light bulbs, some of which constantly burned out.

For clock watchers, the clock shows different time scales. You can observe the slow march of the 5-hour periods on the top bar, or watch each minute pass by on the bottom bar. Unfortunately, reading the precise time requires some mental arithmetic, which makes the clock hard to use.

As for why it’s in the news, some references to a “Berlin Clock” have been made in reference to the famous Kryptos sculpture: Sculptor Offers Another Clue in 24-Year-Old Mystery at C.I.A..

If it’s not a reference to this clock, perhaps it’s a reference to the Alexanderplatz World Clock:

Berlin 376444 640

No Watch: special edition

You can find this elegant 24 hour watch, and other interesting pieces, at No Watch.


If you visit the web site before the end of 2014, you can buy these watches at a reduced price: for a single watch ($100 discount), use coupon code “24hourtime”, for two or more watches (50% discount) the coupon code is “24hourtime24”. The coupon codes are valid for any model in store up to 12/31/2014. Also, free worldwide economic shipping (Registred Air Mail shipping with a tracking) is available with this offer.

If you have any questions, visit the web site.

How does my day look?

A day in the life of architect Le Corbusier:

Corbusiers days

This is one of the entries on an intriguing infographic by R J Andrews posted at infowetrust.com. It shows typical daily routines of some famous historical figures, displaying their work/recreation activities on a 24 hour chart.

Creative routines edit3

The two advantages of the 24 hour analog way of displaying time are that the entire day can be seen at a glance, and that time is displayed in context. Whereas a digital display tells you the time right now, an analog dial can show you the current time in the context of the surrounding time periods.

To use this kind of display to plan your time rather than record it, you could look for some suitable software, although there isn’t much around at the moment. One example I spotted recently is the CandooIt concept, currently available for iPhone and iPads, but perhaps planned for Androids soon, who knows. The idea is that your calendar and other plans can be shown on a circular chart, thus allowing you to see ‘at a glance’ what your day looks like.


However, in its present form, CandooIt is difficult to use with an interface that’s both too minimalistic and confusingly animated, and it doesn’t really provide the features that you would expect from a basic calendar/planning app (such as reading from the built-in calendar…). Hopefully the author can improve the execution and make the concept work.

Butterfly Dial

The Butterfly Dial is an ingenious invention designed to combine both the 12 hour and 24 hour dials into a single 12 hour dial.

It’s much easier to see it in action than try to explain it:

butterfly dial

The video can be seen on YouTube.

It’s no substitute for a true 24 hour dial, but it’s a much neater solution than the Cyclos dial, described in the Design page of this site: