ETA · ETA 2824-2

Tudor Black Bay, Doxa SUB 300 and Hamilton Khaki Field power reserve: inside the ETA 2824-2

The first Tudor Black Bay, the Black Bay 36, the Doxa SUB 300 and older Hamilton Khaki Field and Tissot Seastar automatics all run on the ETA 2824-2. From full it lasts about 38 hours, a little over a day and a half.

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

Watches that use the ETA 2824-2

For about forty years the 2824-2 was the default Swiss automatic with a date, so the list of watches that have used it runs into the thousands. The table below covers the ones people search for most. Many brands rename it: TAG Heuer calls it Calibre 5, Breitling built its B17 on it, and Tudor simply signed it "2824". Inside Swatch Group it has largely been replaced by the 80-hour Powermatic 80, and many independent brands have switched to the Sellita SW200-1, so check the year of your watch.

Specs at a glance

History and where it came from

The 2824 family traces back to the Eterna 1427, introduced in the 1950s when ETA was still Eterna's movement-making arm. The first 2824 appeared in 1971, and the 2824-2, with 25 jewels, followed in 1982. The basic design is past its fiftieth birthday and still in use.

For decades, if a Swiss watch said "automatic" and cost less than a luxury brand's in-house piece, the 2824-2 was usually inside. Tissot, Hamilton, Certina, Doxa, Sinn, Stowa, Steinhart and countless microbrands used it, and bigger names like Tudor, TAG Heuer and Breitling built their own versions on it.

Its patents expired in the early 2000s, and around the same time Swatch Group began cutting ETA supplies to outside brands. Sellita, which had assembled 2824s for ETA, launched its own near-copy, the SW200-1, and it now fills most of the non-Swatch watches that once had a 2824. Inside Swatch Group, the Powermatic 80 took over the same footprint with a longer-running spring. That's why a new Tissot or Hamilton rarely has a 2824 today, while a 2015 one very often does.

Accuracy in the real world

Official tolerances are wide, but the 2824-2 responds very well to regulation. Tudor used a top-grade version in the Black Bay 36, and Monochrome quoted an owner reporting a steady +2 to +3 seconds a day. The Doxa SUB 300's COSC-certified movement is tested to -4/+6 s/day. Standard-grade movements in cheaper watches vary more out of the box, but most can be brought within about ±10 s/day by a watchmaker.

The fast 4 Hz beat helps the rate stay steady when the watch takes a knock, and it gives the seconds hand the smooth sweep people expect from a Swiss watch. The weak point is late in the reserve: like most older designs, the rate can drift as the spring runs down, which is one more reason not to let a 2824 sit for a day and a half before wearing it.

Reliability and servicing

The 2824-2's biggest strength is that almost every watchmaker in the world has serviced one. Service is straightforward, and a five-year interval is the usual recommendation. Its "tractor" reputation was earned over decades in dive watches.

• Parts supply. ETA no longer sells movements in bulk to outside brands. Parts and replacement movements are still available, and the Sellita SW200-1 is close enough that watchmakers treat the two as interchangeable in most cases.
• Brand service. A Tudor, Breitling or TAG Heuer goes back to the brand for a full service; Hamilton and Tissot may fit a replacement movement.
• Hand-winding. Watchmakers generally advise gentle hand-winding on 2824s and their clones. A few turns to start it, then let the rotor do the rest.

Quirks worth knowing

• Casebacks can lie. During Hamilton's switch to the H-10, owners reported Khaki Field watches with "2824-2" printed on the caseback but an H-10 inside. If the reserve matters, check the rotor, not the caseback.
• Rebadged names. A TAG Heuer Calibre 5 or an Oris 733 may be a 2824 or an SW200, depending on the year. They behave the same day to day.
• Date danger zone. Don't use the quickset date between about 9pm and 3am. Here's why.
• Hand-winding feel. Winding through the crown can feel a little gritty compared with a hand-wound movement. That's normal.

How it compares

• Sellita SW200-1: essentially the same design with an extra jewel. At the same grade, watchmakers find no meaningful difference in accuracy.
• Powermatic 80 and Hamilton H-10: the same footprint with 80 hours of reserve at 3 Hz. Better for a rotation; the 2824 is easier for any watchmaker to work on.
• ETA 2836-2: the same movement with a day wheel added, as in the old Tissot Heritage Visodate.
• ETA 2892-A2: thinner and more refined, with a slightly longer 42-hour reserve, at a higher price.
• Seiko NH35: slower 3 Hz beat, looser tolerances and 41 hours, but far cheaper to replace outright.

Living with the 38-hour reserve

Thirty-eight hours is the 2824's weak spot. Take your Black Bay 36 or Doxa SUB 300 off at 6pm on Friday and, from a full wind, it stops around 8am on Sunday. If it went into the drawer half-wound after a desk week, it may stop on Saturday. Either way you'll be setting the time and date before Monday, and that late-night date window is easy to stumble into.

If you rotate watches, a 2824 is the one to put back on first after a break, or to give a few turns of the crown the night before. An older Khaki Field that lives in a drawer between hikes will almost always be stopped when you pick it up. Watch Winder counts down the 38-hour reserve for each watch you own and reminds you before it stops. To check a particular weekend, try the "Will my watch stop?" calculator.

Verdict

The ETA 2824-2 is proven, accurate when regulated, and serviceable almost anywhere. It's the reason a first-generation Tudor Black Bay or a Doxa SUB 300 is such a low-risk watch to own. Its only real weakness today is the short reserve, which newer designs like the Powermatic 80 fix. As a used purchase it's still one of the safest movements you can buy; just check the grade before paying extra, and expect to reset it after most weekends.

FAQ

How long does a Tudor Black Bay 36 run off the wrist?

The Black Bay 36 (79500) uses a modified ETA 2824, which runs for about 38 hours from a full wind. Take it off on Friday evening and it will usually stop some time on Sunday.

How accurate is the Doxa SUB 300?

The current Doxa SUB 300 uses a COSC-certified ETA 2824-2, which is tested to between -4 and +6 seconds a day. Real-world results depend on how you wear and store it.

What movement is in the older Hamilton Khaki Field Auto?

Older Khaki Field Autos used the ETA 2824-2 with about 38 hours of reserve. Current models use the Hamilton H-10 with 80 hours, and some transition-era watches have a 2824 caseback over an H-10.

Does the Tissot Seastar 1000 Automatic hack?

Yes. The older Seastar 1000 (T066.407) uses the ETA 2824-2, which stops the seconds hand when you pull the crown and can be wound by hand.

Why did my Tudor Black Bay stop over the weekend?

The first-generation Black Bay (79220) uses an ETA 2824 with about 38 hours of reserve, so two days off the wrist is enough to stop it. The later in-house MT5602 version runs about 70 hours.

Is the Sellita SW200-1 as good as the ETA 2824-2?

At the same grade, yes. The SW200-1 is a close copy of the 2824-2, and the two perform essentially the same.

How often should an ETA 2824-2 be serviced?

Roughly every five years is the usual recommendation, sooner if the reserve or accuracy drops noticeably.

Sources

• Caliber Corner: ETA Caliber 2824-2
• Teddy Baldassarre: ETA 2824, the history and legacy of a workhorse caliber
• Monochrome: Tudor Heritage Black Bay 36 ref. 79500 review
• Worn & Wound: Doxa Sub 300 review
• Rescapement: Five great watches with ETA 2824 movements

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 ETA 2824-2. 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 38 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.

All ETA movements

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 ETA 2824-2: 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.