JLC Caliber 101

The smallest movement in the world was made in 1929?! It was called the Jaeger-LeCoultre Caliber 101

Just how small is it? I’m glad you asked.

In the past couple of years, there have been numerous strides made in making ever thinner movements. Bulgari currently holds the records for the thinnest minute repeater, tourbillon and automatic watch while Piaget has the thinnest mechanical watch at only 2mm in height. And considering the shape of the modern wristwatch, it only makes sense that they try to make movements as thin as possible. Recently however I stumbled upon another gem, the most compact movement in the world. This award goes to Jaeger-LeCoultre and astonishingly, it was made almost a century ago in 1929. This is the story of the JLC Calibre 101.

Just how compact can a movement get? Well, the calibre 101 has a dimension of 14mm x 4.8mm x 3.4mm and the whole thing weighs less than 1 gram.


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What makes this even more incredible is that the master watchmakers at Jaeger-LeCoultre designed this micro-mechanical wonder back in 1929 without the aid of any Computer Assisted Design program. To get such a compact form factor, JLC stacked the movement into a dual-layer architecture putting the escapement on one level and the barrel on another and the mainspring can only be wound via a flat crown set into the base of the case.

You might be wondering: why would they even need such a minute movement back in 1929 when pocket watches were still all the rage? Well, these tiny movements were used in jewellery pieces from Jaeger-LeCoultre as well as other great jewellery designers of that time. The French President also presented a jewellery watch using this very movement to Queen Elizabeth II which she wore for her coronation in 1953.



The Caliber 101 not only holds the title for the smallest movement to date but it is also one of the oldest movements that continue to be in production. Over more than 90 years, JLC has continuously improved on this calibre in terms of materials and machining, but always maintaining its small stature. This Calibre 101 is now the fourth generation of the movement Caliber 101/4 and has 98 components compared to the 78 of the original. The balance wheel oscillates at 21,600 vibrations per hour (3Hz) and its barrel provides 33 hours of power reserve. And as its original intended purpose, it is still used in the ornate jewellery watches made by the Maison until today.


The Jaeger-LeCoultre 101 Snowdrop
The Jaeger-LeCoultre 101 Snowdrop

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