Rolex · Rolex 3255

Rolex Day-Date 40 and Day-Date 36 power reserve: inside the calibre 3255

The calibre 3255 powers the Rolex Day-Date 40 and Day-Date 36, the watch everyone calls the President. From full it runs for about 70 hours, just under three days.

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

Watches that use the Rolex 3255

The 3255 has one job: running the Rolex Day-Date, with the day of the week spelled out in an arc at 12 o'clock and the date at 3. It was the first of Rolex's current 32-series movements, launched in 2015 in the Day-Date 40, and it reached the Day-Date 36 in 2019. Every Day-Date is made in gold or platinum, so this is also the most expensive-to-own movement on the list.

The 3255 isn't used outside the Day-Date. Its descendants carry the same architecture into other lines: the 3235 (date only), the 3230 (no date) and the 3285 (GMT).

Specs at a glance

History and where it came from

Before 2015, the Day-Date ran on the calibre 3155 in the 36 mm model and the closely related 3156 in the larger Day-Date II. Both were dependable 4 Hz movements with around 48 hours of reserve.

At Baselworld 2015 Rolex replaced the Day-Date II with the slimmer Day-Date 40 and put a completely new movement inside it. Rolex said more than 90% of the 3255's components were new and that the design was covered by 14 patents. The key changes were the Chronergy escapement, a reworked Swiss lever with an openworked escape wheel that Rolex says is about 15% more efficient, and a new barrel with a much thinner wall to fit a longer mainspring. The automatic winding was also sped up to fill that bigger spring. The result was 70 hours of reserve, a full day more than before, in the same 28.5 mm diameter.

The Day-Date 36 kept the 3155 until Baselworld 2019, when the 128238 generation brought it up to the same movement. The 3255 was the template for everything that followed: Rolex used the same architecture for the Datejust's 3235, the GMT's 3285 and the no-date 3230.

Accuracy in the real world

Each Day-Date passes COSC as a bare movement and then Rolex's own test as a finished watch, to -2/+2 seconds a day. Rolex describes this as twice as precise as a standard chronometer. Owners of the Day-Date 40 and 36 generally report new watches running inside that range.

The 3255 was the first 32-series movement, so it's also part of the family where owners and watchmakers have reported some early watches starting to run slow after two or three years. The usual diagnosis is a lubrication problem that lowers amplitude. Rolex hasn't commented publicly, but affected watches have reportedly been fixed under the five-year guarantee. If your Day-Date starts losing several seconds a day while it's still covered, send it back rather than living with it.

The blue Parachrom hairspring is paramagnetic and handles temperature changes and knocks well, so a Day-Date worn every day is less likely to be knocked off rate by a phone or laptop than an older steel-spring watch.

Reliability and servicing

Rolex recommends a service roughly every ten years for watches sold since 2015 and gives a five-year guarantee.

• Brand service. Rolex service centres have full parts access and replace the barrel and mainspring together when needed. For a gold or platinum watch, most owners will want the case refinished by Rolex anyway.
• Independents. The 32-series architecture is harder for independents than the 3155 was. Watchmakers point to the thin-walled barrel that isn't meant to be reopened, the sealed ball-bearing rotor assembly, and parts restricted to Rolex's own network.
• Calendar works. The day and date discs add parts, but they're a mature Rolex design. Use the quickset instead of winding the hands round and round to advance several days.

Quirks worth knowing

• Two quicksets, one crown position. With the crown in the first setting position, turning one way advances the date and the other way advances the day. Pull out once more to set the time; that position stops the seconds hand.
• Instant change. Day and date both snap over at midnight instead of creeping across over an hour or more.
• Setting the day right. Set the time on the correct side of midnight. If the day and date change while the hands show noon, the watch is twelve hours out.
• Unscrew first. The Twinlock crown screws down. Unscrew it before winding and screw it down firmly afterwards.

How it compares

• Rolex 3235: the Datejust's movement, essentially the 3255 without the day disc. Same reserve and accuracy standard.
• Rolex 3135: the date-only relative of the older 3155. Around 48 hours, and easier for independents to service.
• Omega 8900: used in the Aqua Terra 41 and Planet Ocean. Master Chronometer tested to 0/+5 s/day and highly magnetism-resistant, with about 60 hours of reserve.
• Rolex 3285: the GMT-Master II's movement, the same architecture with a second time zone instead of the day.

Living with the 70-hour reserve

Take a fully wound Day-Date 40 off at 6pm on Friday and it should still be running around 4pm on Monday. That's a real change from the 48-hour 3155 in an older Day-Date 36, which would have stopped on Sunday evening.

A Day-Date is also the watch most likely to be saved for occasions, and that's where it catches people out. After a week in the safe it will have stopped, and you'll need to set the day and date as well as the time before you can wear it. A fully wound one survives a normal weekend; one that went into the weekend after a light day of wear may not. Watch Winder counts down this 70-hour reserve for each watch you own and reminds you before it stops, so the President is still running when the occasion comes round. To check a particular weekend, try the "Will my watch stop?" calculator.

Verdict

The 3255 was the movement that started Rolex's modern generation, and it shows the approach at its best: a full extra day of reserve, a hairspring that shrugs off magnetism, and a cased -2/+2 s/day standard, without changing the size of the movement or the look of the watch. In a Day-Date 40 or 36 it means a watch that survives a weekend off the wrist and keeps close time. The trade-offs are long-term: early 32-series watches have had some slow-running reports, and the design leans on Rolex for service. Given what a Day-Date costs, that's a trade most owners will accept.

FAQ

How long does a Rolex Day-Date 40 run off the wrist?

About 70 hours from full, just under three days. The Day-Date 40 has used the calibre 3255 since it launched in 2015.

What is the power reserve of the Rolex Day-Date 36?

Current Day-Date 36 models (128238 and siblings, from 2019) use the calibre 3255 with about 70 hours. Earlier Day-Date 36 models with the calibre 3155 ran for about 48 hours.

How accurate is the Rolex President?

Rolex tests every cased Day-Date to -2/+2 seconds a day as a Superlative Chronometer. Owners generally report new watches running within that range.

Does the Rolex Day-Date hack?

Yes. Pulling the crown out to the time-setting position stops the seconds hand so you can set it precisely.

How do you set the day on a Rolex Day-Date 40?

Unscrew the crown and pull it to the first setting position. Turning it one way advances the date and the other way advances the day.

Will my Day-Date stop over the weekend?

Not if it was fully wound. A full Day-Date runs about 70 hours, enough for Friday evening to Monday afternoon, but one that started the weekend half-wound can stop on Sunday.

Sources

• Monochrome: Introducing the Rolex Day-Date 40 with the new calibre 3255
• aBlogtoWatch: Updated Rolex Day-Date 36 watches for 2019
• Grail Watch Reference: Rolex 3255
• Quill & Pad: A watchmaker's comparison of Rolex calibres 3135 and 3235

Keeping it running

• On an average day an automatic gains roughly 4 hours of reserve per hour on the wrist, so about 18 hours of wear fills the Rolex 3255. 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 70 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 Rolex movements · Other 70-hour 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 Rolex 3255: 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.