One of the most difficult accomplishments in horology is producing an ultra-thin watch movement.

As with other notable accomplishments, creating an ultra-thin watch movement typically involves serious engineering to overcome difficulties. Perhaps the most difficult aspect of thinness are the questions of durability and structural rigidity. It is critical that movement plates be stiff enough to resist flexing or warping over time, since gears must be precisely located. This is especially true with an ultra-thin movement since these have similarly-thin gears that could un-mesh if they come out of alignment.

Most ultra-thin movements include simpler bridge and cock setups, often with one bridge doing the task of two. This presents serious engineering challenges when combined with the necessity to move gears both vertically and horizontally to make space.

One potential solution to these problems is to combine the movement and case into a single unit. This causes issues with servicing but typically leads to greater structural stability.

Traditional movements are measured in two dimensions Diameter and height or thickness. Although it would be tempting to trade thickness for width, this is not practical Some components (notably the balance and escapement and barrel) must have a minimal thickness to be functional. These create a minimum thickness that can be achieved. This is especially true for ultra-thin tourbillons and automatic movements since these components take up quite a bit of room in a movement.

Threshold 300 mm³

• Watch movement Citizen G720 (2002) 30 mm² surface area, 73 mm³ volume (5.0 mm x 6.0 mm x 2.5 mm)
• JLC 101 228 mm³

• See Also Ultra-thin quartz

Threshold 1.5 mm

• Seiko 9A85 0.85 mm (1989)
• Seiko 6720 0.89 mm (1980)
• Seiko 9320 0.90 mm (1978)
• Citizen 690 0.98 mm (1978)
• ETA 210.001 0.98 mm (1983, based on the Delirium)
• ETA 282.001 1.20 mm
• JLC 608 1.6 mm
• JLC 601 1.8 mm

Threshold 2.1 mm

• LeCoultre 145 1.38 mm
• Audemars Piguet 2003 (JLC 803/Vacheron Constantin 1003) 1.64 mm
• Piguet 21 (Patek Philippe 175/177) 1.75 mm
• JLC 849 1.85 mm
• Seiko 6800 1.98 mm
• Piaget 9P 2 mm
• Piaget 40P 2 mm
• Piaget 430P 2.1 mm
• Piaget 438P 2.1 mm
• Piaget 450P 2.1 mm
• Lange L093 2.9 mm

Threshold 2.4 mm

• BLV138, 2.23 mm (introduced at Baselworld 2017 in the Bulgari Octo Finissimo Automatic)
• Piaget 12P 2.3 mm
• Piaget 1208P 2.35 mm
• Piaget 1200P 2.36 mm

Threshold 2.5 mm

• JLC 920 (Audemars Piguet 2120/Patek Philippe 28-255/Vacheron Constantin 1120) 2.45 mm
• JLC 898 3.3 mm

Threshold 3.3 mm

• Piaget 1205P 3 mm (micro-rotor date)
• JLC 920 (Audemars Piguet 2121/Vacheron Constantin 1121) 3.05 mm
• JLC 889 (IWC 3254) 3.25 mm (central rotor date)
• JLC 899 3.3 mm (central rotor date)
• JLC 920 (Audemars Piguet 2122/Patek Philippe 28-255 C/Vacheron Constantin 1122) 3.4 mm (with central seconds)

Threshold 6 mm

• JLC 891/2-448 5.53 mm

Threshold 6 mm

• Audemars Piguet 2120 3.95 mm (modular, central rotor)
• JLC 868 4.72 mm (central rotor)
• Piaget 855P 5.6 mm (central rotor)

Threshold 5 mm

• Bulgari BVL 318 (2019) 3.3 mm (chronograph GMT)
• F. Piguet 1180 (1987) 3.95 mm (column wheel chronograph)
• Piaget 883P 4.65 mm (flyback chronograph)

Threshold 6 mm

• Bulgari BVL 388 (2020) 3.5 mm (peripheral automatic skeleton chronograph, column wheel and horizontal clutch)
• Vacheron Constantin 3500 5.2 mm (split seconds chronograph, peripheral rotor, limited production)
• Frederic Piguet 1185 5.4 mm (central rotor)
• Piaget 880P 5.6 mm (flyback chronograph, central rotor)

Threshold 4 mm

• Gerald Genta, 2.72 mm
• Bulgari BVL 362, 3.12 mm (thinnest minute repeater, introduced in Bulgari Octo Finissimo Minute Repeater 2016)
• Vacheron Constantin 1755 3.28 mm (introduced 1992)
• Vacheron Constantin 1731 3.9 mm (introduced 2013)
• Piaget 1290P 4.8 mm (micro-rotor automatic)

Threshold 3.5 mm

• Bulgari BVL 266 1.95 mm
• Arnold and Son UTTE, 2.97 mm
• Breguet 581DR 3 mm
• Piaget 600P 3.5 mm
• Piaget 640P 3.5 mm
• Audemars Piguet 2924 4.46 mm

• Bulgari BVL 288 1.95 mm (introduced 2018)
• Chopard Cal. 96.24-L 3.3 mm (micro-rotor flying tourbillon 2019)
• VMF 3024 3.95 mm (central-rotor automatic)
• Audemars Piguet 2870 4.8 mm (hammer automatic, introduced 1986)
• JLC 362 4.8 mm (minute repeater, tourbillon, peripheral automatic, introduced 2014)
• Piaget 1270P 5.5 mm (micro-rotor automatic)

Threshold 2 mm

• Concord Delirium IV 0.98 mm (not wearable)
• Concord Delirium 1.98 mm

Threshold 4 mm

• Integrated mechanical movement Piaget Altiplano Ultimate Concept, 2 mm including Cal. 900P-UP (introduced at Baselworld 2017)
  • Piaget 900P 3.65 mm (introduced 2013)
• Separate case and movement Jaeger-LeCoultre Master Ultra-Thin Squelette, 3.60 mm (introduced 2015)
  • Jaeger-LeCoultre Master Ultra-Thin Jubilee, 4.05 mm (introduced 2013)
• Thinnest automatic watch Bulgari Octo Finissimo Tourbillon Automatic, 3.95 mm (thinnest automatic watch and tourbillon, introduced at Baselworld 2018)
  • Piaget 910P 4.30 mm (thinnest automatic)
  • Bulgari Octo Finissimo Automatic, 5.15 mm
  • Piaget Altiplano Automatique, 5.25 mm Cal. 1208P
  • Vacheron Constantin Patrimony Contemporaine Ultra-Thin, 8.09 mm (introduced 2013)
• Thinnest tourbillon watch Bulgari Octo Finissimo Tourbillon Automatic, 3.95 mm (thinnest automatic watch and tourbillon, introduced at Baselworld 2018)
  • Audemars Piguet 25643, 4.8 mm (thinnest tourbillon watch with Cal. 2870, introduced in 1986)
  • Bulgari Octo Finissimo Tourbillon, 5.00 mm (thinnest tourbillon on introduction in 2014)
  • Piaget Emperador Coussin Tourbillon Automatic (2011) - 5.35 mm
  • Breguet Classique Tourbillon Extra-Thin Automatic, 7 mm (2014)
  • Arnold and Son UTTE, 8.34 mm (thinnest tourbillon in 2015)
• Thinnest complicated watch Bulgari Octo Finissimo Minute Repeater, 6.85 mm (thinnest complicated watch, minute repeater, introduced 2016)
  • Jaeger-LeCoultre Hybris Mechanica 11, 7.9 mm (thinnest automatic repeater, introduced in 2014)
  • Piaget Emperador Coussin Ultra-Thin Minute Repeater, 9.4 mm (introduced 2013)
• Thinnest chronograph watch Bulgari Octo Finissimo Chronograph GMT (2019), 6.90 mm (thinnest chronograph, GMT)
  • Piaget Altiplano Chronograph Flyback, 8.24 mm (thinnest chronograph, flyback)