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Could a mechanical watch run for a full month without being wound? The A. Lange & Söhne Lange 31 comes close: its manually wound movement has a stated 744-hour reserve, or 31 days. It does not wind itself while you wear it. Instead, two unusually long mainsprings and a constant-force mechanism make the extended interval possible—and the 45.9 mm-wide, 15.9 mm-thick case is a substantial part of the trade-off.
What does the Lange 31’s 31-day reserve mean?
The “31” refers to days of power reserve. A. Lange & Söhne specifies 744 hours for the current LANGE 31, reference 130.039F. That is the manufacturer’s stated running time after winding, not a promise that the watch will keep identical time throughout the month.
It is a manually wound watch, not an automatic. You can leave it unworn for much of its reserve, but it still needs winding before the movement can run for another interval. Its appeal is the unusually long gap between winding sessions, rather than self-winding convenience.
The current European English product page lists a 3 Hz balance frequency, equivalent to 21,600 semi-oscillations per hour, alongside the 744-hour reserve. The page does not publish a comparative accuracy test across the full month, so the reserve figure should not be read as a quantified accuracy result.
#1 Best Overall
- MANUAL WINDING: Designed for precision, this hand-wound watch is powered by the exclusive H-23 movement, offering an extended power reserve for reliable performance.
- WATER RESISTANT TO 100M: Withstands 10 bar (100 meters), ideal for swimming and outdoor pursuits. Perfect for those who demand resilient accessories that accompany them confidently on their explorative journeys.
- BUILT FOR ADVENTURE: Featuring a 40mm stainless steel case, a white dial and stainless steel bracelet, this watch combines durability and functionality. With Super-LumiNova and sapphire crystal, it’s ready to tackle your outdoor challenges.
- PREMIUM MATERIALS: Stainless steel bracelet with folding clasp offers day-long comfort. The clean lines and sophisticated design make it the perfect accessory for both casual wear and formal attire, merging functionality with fashion.
- RICH HERITAGE: Over a century of Hamilton's legacy in field watches, admired for precision. Originally designed for WWI soldiers, these timepieces combine rugged durability with history, showcasing Hamilton's commitment to quality and innovation.
How does the movement store and release a month of power?
Two exceptionally long mainsprings store the energy
A. Lange & Söhne’s 2017 technical explanation says the movement uses two mainsprings, each 185 cm long. Storing enough energy for 744 hours is only part of the engineering challenge: the torque produced by a wound spring changes as it unwinds, while the escapement needs a controlled supply of energy.
A constant-force mechanism meters energy
The maker says its patented constant-force escapement sits between the spring barrel and the going train. It delivers energy to the escapement every ten seconds, helping regulate the changing force from the springs. A limiter stops the movement after the 31-day run. These are the manufacturer’s descriptions of the mechanism; the sources do not provide an independent accuracy test demonstrating its performance over that period.
Rank #2
- MANUAL WINDING: Designed for precision, this hand-wound watch is powered by the exclusive H-23 movement, offering an extended power reserve for reliable performance.
- WATER RESISTANT TO 100M: Withstands 10 bar (100 meters), ideal for swimming and outdoor pursuits. Perfect for those who demand resilient accessories that accompany them confidently on their explorative journeys.
- BUILT FOR ADVENTURE: Featuring a 40mm stainless steel case, a black dial and stainless steel bracelet, this watch combines durability and functionality. With Super-LumiNova and sapphire crystal, it’s ready to tackle your outdoor challenges.
- PREMIUM MATERIALS: Stainless steel bracelet with butterfly clasp offers day-long comfort. The clean lines and sophisticated design make it the perfect accessory for both casual wear and formal attire, merging functionality with fashion.
- RICH HERITAGE: Over a century of Hamilton's legacy in field watches, admired for precision. Originally designed for WWI soldiers, these timepieces combine rugged durability with history, showcasing Hamilton's commitment to quality and innovation.
The 2017 press account also describes an integrated backstop ratchet for winding and a torque limiter intended to prevent unintended overwinding. The point of the system is not simply to fit more spring into a watch, but to manage how that stored energy reaches the escapement over an unusually long interval.
How do you wind the Lange 31?
Winding is not done with a conventional crown. According to A. Lange & Söhne’s 2017 explanation, a separate key fits a square socket recessed into the sapphire case back and tensions the mainsprings. The current model page identifies the watch as manually wound but does not restate the key details.
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- MANUAL WINDING: Designed for precision, this hand-wound watch is powered by the exclusive H-23 movement, offering an extended 80-hour power reserve for reliable performance.
- WATER RESISTANT TO 100M: Withstands 10 bar (100 meters), ideal for swimming and outdoor pursuits. Perfect for those who demand resilient accessories that accompany them confidently on their explorative journeys.
- BUILT FOR ADVENTURE: Featuring a 40mm stainless steel case, a black dial and green textile strap, this watch combines durability and functionality. With Super-LumiNova and sapphire crystal, it’s ready to tackle your outdoor challenges.
- PREMIUM MATERIALS: Textile strap with pin buckle offers day-long comfort. The clean lines and sophisticated design make it the perfect accessory for both casual wear and formal attire, merging functionality with fashion.
- RICH HERITAGE: Over a century of Hamilton's legacy in field watches, admired for precision. Originally designed for WWI soldiers, these timepieces combine rugged durability with history, showcasing Hamilton's commitment to quality and innovation.
The supplied key is therefore central to the operating routine: the long reserve reduces how often winding is needed, but winding remains necessary. The available sources do not establish replacement-key availability or aftermarket compatibility.
What is the current Lange 31 configuration?
The manufacturer’s European English listing, checked on October 7, 2026, describes reference 130.039F / LSLS1303AC in 750 white gold. The stated specifications are:
Rank #4
- AUTOMATIC WITH MANUAL WINDING MOVEMENT: powered by the reliable 4R36 Caliber, these Seiko automatic watches for men combine automatic and manual winding capabilities.
- DURABLE UTILITY: this watch is water-resistant to 10 bar, and boasts a stainless steel watch case with comfy beige nylon strap, ensuring it lives on your wrist as a robust yet stylish sports watch
- BLACK DIAL: this men's watch features a black dial and beige luminous dial indicator hands and numerals for easy visibility
- DAY/DATE DISPLAY: the day and date are both on the watch face, helping you stay organised and on top of your schedule
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- Case: 45.9 mm in diameter and 15.9 mm high; 22 mm lug distance.
- Water resistance: 3 bar.
- Dial: grey solid silver, with oversized date and power-reserve indicator.
- Movement: calibre L034.1, manual winding, 406 parts, 744-hour reserve, 3 Hz frequency, and constant-force escapement.
- Back: sapphire crystal.
- Strap and buckle: dark-brown alligator leather strap and 18-carat white-gold deployant buckle.
- Edition and availability: limited to 100 pieces and listed as available exclusively through Lange boutiques; the manufacturer gives price upon request.
The official specifications and boutique information are on A. Lange & Söhne’s LANGE 31 product page. Boutique-exclusive listing does not establish that a particular boutique currently has one in stock.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How does the Lange 31 wear?
Its official dimensions describe a large, thick watch: 45.9 mm across and 15.9 mm high. Those figures indicate scale, but cannot predict fit on every wrist.
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Best Value
- MANUAL WINDING: Designed for precision, this hand-wound watch is powered by the exclusive H-23 movement, offering an extended power reserve for reliable performance.
- WATER RESISTANT TO 100M: Withstands 10 bar (100 meters), ideal for swimming and outdoor pursuits. Perfect for those who demand resilient accessories that accompany them confidently on their explorative journeys.
- BUILT FOR ADVENTURE: Featuring a 40mm stainless steel case, a white dial and green textile strap, this watch combines durability and functionality. With Super-LumiNova and sapphire crystal, it’s ready to tackle your outdoor challenges.
- PREMIUM MATERIALS: Textile strap with pin buckle offers day-long comfort. The clean lines and sophisticated design make it the perfect accessory for both casual wear and formal attire, merging functionality with fashion.
- RICH HERITAGE: Over a century of Hamilton's legacy in field watches, admired for precision. Originally designed for WWI soldiers, these timepieces combine rugged durability with history, showcasing Hamilton's commitment to quality and innovation.
In a 2017 hands-on review, Monochrome’s Brice Goulard called the watch massive on the wrist, while noting that its short, curved lugs helped it remain wearable. That is one reviewer’s assessment, not a guarantee of comfort or fit. The same review reported movement dimensions of 37.3 mm wide and 9.6 mm thick, and described the large barrel as occupying much of the movement; the current product page does not repeat those movement measurements. See Monochrome’s 2017 hands-on review.
What does it cost, and how available is it?
The current manufacturer listing says price upon request and identifies the watch as a 100-piece limited edition sold exclusively through Lange boutiques. It does not give a public retail price, and the listing does not confirm current inventory.
Monochrome reported €142,300 for the white-gold launch edition in its 2017 coverage. That is historical launch pricing, not a current quote for reference 130.039F. A buyer seeking today’s price or availability needs to ask a boutique.
What is the real trade-off behind the 31-day reserve?
The reserve is a serious mechanical achievement, but it is not an isolated convenience feature. The watch combines two long mainsprings, a timed constant-force system, a special key-winding arrangement, and a large case. For someone who wants to wear a watch daily without winding it each morning, a month-long interval may be useful. For someone who prioritizes a compact, lightweight watch or automatic winding, the Lange 31’s defining engineering comes with meaningful compromises.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →The available sources do not establish a current, like-for-like competitor comparison or comparable accuracy results. Monochrome’s 2017 review noted that other watches later offered higher stated reserves, including the Hublot MP-05 LaFerrari at 50 days, using 11 mainspring barrels. That dated comparison illustrates that a larger reserve can involve a very different architecture; it does not establish present availability or a current ranking.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
