The Lange 1 is signature watch model from A. Lange & Söhne produced since 1994.

When Walter Lange decided to re-launch his family brand after the reunification of Germany, he set about designing a signature model for the brand. The result was the Lange 1, which remains the one of the best-known and respected watches from A. Lange & Söhne today. It combines an asymmetrical dial with a two-window big date mechanism, a combination that has stood the test of time. Just as important as the modern design, the Lange 1 used an in-house movement with traditional Glashütte elements, including a three-quarter plate design and gold chatons.

The first patented element of the new Lange is the two-window big date found at 1 00. It is designed to resemble the “Five-Minute Clock” above the stage at the Semper Opera House in Dresden, the first digital clock ever created. The Five-Minute Clock was designed by Ferdinand A. Lange and his mentor, Johann Christian Friedrich Gutkaes in 1841. The history of this complication is nonetheless modern in the Lange 1, and also inspired the signature Zeitwerk.

The dial of the Lange 1 features four elements centered on an isosceles triangle pointing toward the main hour/minutes dial at the traditional 9 00 position. The base of the triangle runs from the centerpoint of the patented big data window through the power reserve indicator pinion, to the small seconds subdial. The size of these elements is meant to evoke the golden ratio, bringing an intangible harmony to the asymmetric dial layout. This same arrangement would continue with later pieces, including the Grant Lange 1 and Lange 1 Tourbillon but would be flipped side-to-side for the automatic Lange 1 Daymatic.

The Lange 1 was unveiled alongside three other models (the Arkade, Saxonia, and Tourbillon "Pour le Mérite") at Dresden Castle on October 24, 1994. The initial production of just 123 watches was already sold out 12 jewelers in Germany, Austria, and Switzerland had been given a preview and all had taken as many as were available. Since that day, the Lange 1 has been awarded more prizes than any other, including Watch of the Year 1995 and 1997.

All original Lange 1 models are designated as model 101 or 151, with leather strap or bracelet, respectively. The watch is equipped with the manual winding manufacture movement Lange L901.0, hacking seconds, power reserve indicator (called “UP and DOWN display” at Lange) and big date. The dial is in solid silver; the hands are in gold. The watch is available in numerous case and dial variants, with crocodile leather or metal bracelet.

The Lange 1 movement, Cal. L901.0 was designed and produced entirely in-house apart from the Nivarox balance spring and Gyromax-style balance. It has two barrels for consistent power delivery, a feature noted on the dial as “Doppelfederhaus” and sometimes confused as the model name. Although designed in the classic three-quarter plate style with chatons, two cutouts in the plate make for easier assembly. The movement also features a date corrector pusher at 10 00.

The earliest pieces were models 101.001 (yellow gold case and hands and champagne dial), 101.002 (yellow gold case, blued hands, and silver dial), and 101.005 (platinum case, rhodium hands, and silver dial). These all featured a solid case back, but a sapphire crystal display back was introduced the next year, with corresponding models 101.021, 101.022, and 101.025. The solid case back was retired in 1997, along with the introduction of white gold/blue dial (model 101.027) and pink gold/black dial (model 101.031) versions. Pink gold/silver dial version (model 101.032) and single-year yellow gold/blue dial (model 101.028) models were introduced in 1998.

The first limited-edition Lange 1 model since the original was the Lange 1A (model 112.021). Introduced in 1998, it includes an engine-turned gold dial and just 100 examples were produced. Another rare early Lange 1 is the stainless steel model (101.026), created on request for special clients and retailers. Both of these are much prized today.

Over the ensuing years, Lange produced the Lange 1 in many variations, notably including a platinum blacked-out “Darth” model (101.035) and white gold/silver dial/luminous hands model (101.039). A smaller Lange 1 model, the Little Lange 1, appeared in 1997 and evolved into a ladies model. Lange produced matched sets of the original and Little Lange 1 in limited editions of color and dial texture.

The Lange 1 line expanded in 2000 with the introduction of the Lange 1 Tourbillon. A model with a moon phase indication, the Lange 1 Moonphase, appeared in 2002, and the larger Grand Lange 1 joined the line in 2003. The Lange 1 Time Zone appeared in 2005.

The first automatic, the Lange 1 Daymatic came in 2010 and featured a flipped dial, with the time at 3 00. This layout was also used for the complicated 2012 Lange 1 Tourbillon Perpetual Calendar, another automatic.

The Lange 1 was entirely refreshed for 2015 with a new movement and case, though the essential elements remained. Introduced at SIHH, the all-new Lange 1 features a new movement, Cal. L121.1, with identical specifications but many updates. Notable is the free-sprung in-house balance wheel with eccentric weights rather than Nivarox and screws. The entire wheel train was redesigned and now resides under a single plate without the two cutouts previously seen. The jewel count was also reduced, from 53 to 43, and there are now 8 rather than 9 chatons. Overall parts count is up, however, from 365 to 368.

The case remained the same size, 38.5 mm, though the bezel and dial lettering is slightly narrower to give it a more modern look.

The rest of the family was also revised in this decade. The first was the thinner 2012 Grand Lange 1, which got its own moon phase model in 2014. The regular Lange 1 Moonphase was similarly revised in 2016 and a Little Lange 1 Moonphase appeared in 2017.

In 2019, Lange introduced the 25th Anniversary editions in white gold, limited to 250 examples. It features a silver dial with blue printing and blued steel hands and an hinged case back with an engraving of the Lange headquarters. The movement is Lange's Cal. L121.1. Lange will release 10 such 25th Anniversary models in all, each limited to 25 examples.

The “original” Lange 1 has spawned a family of related models

• Lange 1, Ref. 101 (1994) - Solid caseback
  • Lange 1, Ref. 101 (1995) - Sapphire caseback
  • Lange 1, Ref. 110
  • Lange 1, Ref. 151
  • Lange 1A (1998) - Limited edition (100 pieces) with engine-turned gold dial
  • Stainless steel case (1998) - Extremely limited production
  • Lange 1, Ref. 191 (2015) - New Cal. L121.1 movement
• Little Lange 1, Ref. 181 (1997) - Smaller 36.1 mm case, Cal. L901.4, no date corrector
  • Little Lange 1 Soiree (2014)
• Lange 1 Tourbillon, Ref. 704 (2000) - Cal. L961.3 Tourbillon
• Lange 1 Moonphase, Ref. 109 (2002) - Cal. L121.3 Moon phase, 38.5 mm case
  • Lange 1 Moonphase, Ref. 192 (2016) - New Cal. L121.3 movement with day/night indicator
  • Little Lange 1 Moonphase, Ref. 182 (2017) - New Cal. L121.2 movement, 36.8 mm case
• Grand Lange 1 (2003) - Larger 41.9 mm case, same movement
  • Grand Lange 1, Ref. 117 (2013-present) - Thinner Cal. L905.1 movement, 40.9 mm case
  • Grand Lange 1 Moonphase, Ref. 139 (2014) - Cal. L905.3 41.9 mm case, moon phase in main dial
• Lange 1 Time Zone, Ref. 116 (2005) - Cal. L031.1 Second time zone
• Lange 1 Daymatic, Ref. 320 (2010) - Automatic movement, dial arrangement swapped left to right
• Lange 1 Tourbillon Perpetual Calendar, Ref. 720 (2012) - Cal. L082.1 Automatic tourbillon with perpetual calendar, swapped dial

Over the years, Lange has also issued sets of the Lange 1 and “Kleine” Lange 1 for special occasions

• Lange 1 “Luna Mundi” (2003) - Set of two Lange 1 Moonphase watches, “Southern Cross” and “Ursa Major”
• Lange 1 Moonphase and Flyback Chronograph “Dresden” (2006)
• Lange 1 “Floral” (2007) - Lange 1 and Little Lange 1 with floral patterned gold dial
• Lange 1 “Black Dial” (2014) - 20th Anniversary Lange 1 and Little Lange 1 with pink gold case and black dial
• Lange 1 “Platinum” (2014) - 20th Anniversary Lange 1 and Little Lange 1 with platinum case and rhodium dial
• Lange 1 “Platinum Black” (2014) - 20th Anniversary Lange 1 and Little Lange 1 with platinum case and black dial
• Lange 1 “Pink Gold” (2014) - 20th Anniversary Lange 1 and Little Lange 1 with pink gold case and silver dial
• Lange 1 “White Gold” (2014) - 20th Anniversary Lange 1 and Little Lange 1 with white gold case and blue dial