Cartier · Cartier 1847 MC

Cartier Santos, Pasha and Ballon Bleu power reserve: inside the 1847 MC

The Santos de Cartier, the Pasha de Cartier, the 40 mm Ballon Bleu and the Clé de Cartier all run on Cartier's in-house 1847 MC, which lasts about 42 hours off the wrist. That's just under two days, so a watch taken off on Friday evening will usually have stopped by Sunday.

Updated September 2026 · Based on manufacturer specs, published reviews and watchmaker/owner reports

Watches that use the 1847 MC

If your automatic Cartier has three hands and was made since about 2016, the 1847 MC is the most likely engine inside. It's Cartier's entry-level in-house calibre and it has gradually replaced the ETA movements the brand used to buy in. Both sizes of the Santos use it, as do both sizes of the Pasha, so choosing between a large and a medium model makes no difference to the reserve.

Not every Cartier on the wrist is an 1847 MC, though. Most Tank Must models are quartz or solar-powered, the Santos-Dumont is quartz or hand-wound, and older Ballon Bleus used a different, bought-in automatic. If the reserve matters to you, check the caseback or the reference before relying on the figures here.

Specs at a glance

History and where it came from

For decades, Cartier's automatic watches used movements bought in from ETA, often with a Cartier calibre number stamped on. As Monochrome put it when the Santos 100 switched over in 2016, that watch had been "powered for decades by an ETA movement". That changed with the Clé de Cartier at SIHH 2015, which introduced the 1847 MC. The name comes from the year Cartier was founded, 1847, and "MC" stands for Manufacture Cartier.

The movement is made in Valfleurier, the Richemont group's movement workshop, and was designed as a like-for-like replacement for an ETA workhorse: 25.6 mm across, 4 Hz, a date or no date, one barrel. That's why Cartier could drop it into existing cases like the Santos 100 in 2016 and then build the 2018 Santos relaunch, the 2020 Pasha and the 2021 Ballon Bleu 40 mm around it.

Later versions gained better protection against magnetism: an escapement using non-magnetic nickel-phosphorus parts and a paramagnetic shield around the movement. The finishing is neat but plain, with Côtes de Genève or wave-pattern stripes on the bridges and rotor.

Accuracy in the real world

Cartier doesn't sell chronometer-certified watches, but Fratello reports a claimed accuracy of +7/-3 seconds a day for the 1847 MC. That's a respectable in-house standard: tighter than the loosest grades of ETA movements, looser than a COSC chronometer or a modern Rolex.

Owners on watch forums generally describe good timekeeping from Santos and Pasha models, often within a few seconds a day, and some say they see Rolex-like rates in daily wear. As always with individual reports, expect variation from watch to watch, and remember that rate changes as the mainspring runs down. On a 42-hour movement, the last few hours come around quickly if you don't wear it every day.

The anti-magnetic parts help more than most people expect. Phones, laptop speakers and bag clasps are the usual cause of a watch suddenly gaining minutes a day, and the 1847 MC is better protected against that than the ETA movements it replaced.

Reliability and servicing

The 1847 MC has been in production for a decade and is used across Cartier's highest-volume watches, and there's no widely reported systemic fault. It's a conventional single-barrel, 4 Hz three-hander, which is about as proven a layout as watchmaking has.

• Brand service. It's an in-house calibre, so Cartier's own service network is the normal route. Parts aren't generally available to independents.
• Independents. A skilled independent can work on it, but parts access is the limiting factor, so ask before you send a Santos or Pasha anywhere other than Cartier.
• Interval. We couldn't confirm a fixed interval from Cartier for this calibre. Have it checked if the rate drifts noticeably or a full wind no longer lasts close to two days.

Quirks worth knowing

• Short reserve for the price. Time+Tide's reviewer put it plainly: 42 hours isn't impressive in an era when 72 hours "seems to be the new normal". It's the one spec where a Santos trails a Tudor or a Tissot.
• Small crowns. The Pasha's real crown sits under a chained cap and is tiny, and the Santos crown is guarded. Hand-winding works, but it's fiddly; Monochrome needed fingernails on the Pasha.
• Small movement in a big case. In the 40 mm Ballon Bleu and the 41 mm Pasha, the date window sits well in from the edge because the movement is small for the case. It's cosmetic, but it's why the date looks a little lost.
• Setting the date. As with most date movements, avoid quick-setting the date late in the evening. Here's why.

How it compares

• ETA 2824-2 / Sellita SW200: the movements the 1847 MC was designed to replace. Same size and beat, about 38 hours, and easier for any watchmaker to service.
• ETA 2892: the thinner, higher-grade ETA that powered many older luxury automatics. Similar reserve, similar accuracy in good examples.
• Rolex 3230: the Oyster Perpetual's movement: 70 hours and -2/+2 s/day. It shows what the 1847 MC gives up for its slimness and price.
• Omega 8800: 55 hours and METAS Master Chronometer certification in a similar price bracket.
• IWC 82000: Richemont's sportier in-house option, with 60 hours.

Living with the 42-hour reserve

This is where the 1847 MC asks the most of you. Take your Santos off at 7pm on Friday and, even if it was fully wound, it stops around lunchtime on Sunday. By Monday morning you'll be resetting the time and the date. The same goes for a Pasha or a Ballon Bleu that sits out a weekend.

A partly wound watch is worse. A Santos worn for a few quiet hours at a desk may carry only a day's charge, so it can stop overnight. If you rotate your Cartier with other watches, wind it 30 to 40 turns by the crown before putting it down, or plan to reset it. Watch Winder counts down this 42-hour reserve for each watch you own and reminds you before it stops, which is most useful on exactly this kind of short-reserve movement. To check a specific weekend or trip, try the "Will my watch stop?" calculator.

Verdict

The 1847 MC does its job without drama. It's slim enough to keep the Santos and Pasha elegant, it's accurate to a sensible in-house standard, and it's better protected against magnetism than the ETA movements it replaced. People buy these watches for the design, and the movement doesn't let the design down. The weak spot is the reserve: at 42 hours, a Cartier will stop over most weekends off the wrist. If you wear your Santos every day, you'll never notice. If you rotate, plan to wind it.

FAQ

How long does a Cartier Santos run off the wrist?

A fully wound Santos de Cartier with the 1847 MC runs for about 42 hours, a little under two days. If it was only partly wound, it will stop sooner.

Why did my Cartier Santos stop over the weekend?

With about 42 hours of reserve, a Santos taken off on Friday evening will normally stop some time on Sunday, even when fully wound. That's expected behaviour, not a fault.

How accurate is the Cartier Santos?

Cartier doesn't certify the Santos as a chronometer, but the 1847 MC's claimed accuracy is +7/-3 seconds a day. Many owners report better than that in daily wear.

What movement is in the Pasha de Cartier 41mm?

The automatic three-hand Pasha de Cartier in both 41 mm and 35 mm uses the in-house 1847 MC, with a 4 Hz beat and about two days of reserve. Skeleton and tourbillon Pashas use different movements.

Does the Cartier Ballon Bleu have an in-house movement?

The 40 mm Ballon Bleu updated in 2021 uses the in-house 1847 MC. Older Ballon Bleus and some other sizes used bought-in automatic or quartz movements, so check the reference.

Can you hand-wind a Cartier Santos?

Yes. The 1847 MC winds through the crown as well as the rotor. From stopped, about 30 to 40 turns of the crown in its normal position gives it a good start.

Is the Cartier 1847 MC antimagnetic?

It's better protected than a typical movement, with non-magnetic nickel-phosphorus escapement parts and a paramagnetic shield. It's still best kept away from strong magnets such as speaker drivers and bag clasps.

Sources

• Monochrome: 2020 Pasha de Cartier 41mm review (calibre 1847 MC specs)
• Monochrome: 2018 Cartier Santos Large review
• Monochrome: Ballon Bleu de Cartier 40mm with in-house movement
• Fratello: A Cartier watch does everything a Rolex does
• Time+Tide: The Cartier Clé de Cartier in steel

Keeping it running

• On an average day an automatic gains roughly 4 hours of reserve per hour on the wrist, so about 10 hours of wear fills the Cartier 1847 MC. Desk days charge more slowly.
• Most automatics can also be wound by the crown. If yours has stopped, a few dozen turns gets it going before you put it on.
• Off the wrist it stops about 42 hours after it was last full. Stopped sooner?
• On a watch winder, start at about 650 turns per day, both directions. Winder settings for every movement.
• If it does stop, don't set the date between 9pm and 3am. Check if it's safe.

Never let it stop

Watch Winder counts down the reserve of every watch you own and reminds you before one stops. It already knows the Cartier 1847 MC: type your watch's name and the reserve fills itself in.

Manufacturer's published figure. Real reserve varies with the watch's age and service; check your manual.