Citizen (Miyota) · Miyota 8215

Timex Marlin Automatic, Bulova and Citizen power reserve: inside the Miyota 8215

The Timex Marlin Automatic, many Bulova and Invicta automatics and countless entry-level watches run on the Miyota 8215, and Citizen's Tsuyosa uses a close sibling. From a full wind it lasts about 42 hours, a little under two days.

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

Watches that use the Miyota 8215

The 8215 is one of the most widely used automatic movements ever made. Because it's cheap and tough, it turns up in fashion-brand automatics, big-name entry-level watches and early microbrand divers, often without the brand naming it. Citizen, which owns Miyota, uses its own-numbered versions of the same 82 family in its basic automatics.

Specs at a glance

History and where it came from

Miyota is Citizen's movement-making arm, named after the town in Nagano where Citizen built a movement factory in 1959. It introduced the 8215 in 1977, and Time+Tide calls it the baseline of Miyota's mechanical output. From the early 1980s Miyota sold movements to other brands off the shelf, and the 8215 became the automatic you could buy by the thousand at a very low price.

That's why it's everywhere. The design is simple, tolerant of rough handling and cheap to make, so brands from Timex and Bulova to fashion labels and early microbrands built entry-level automatics around it. Miyota later added the slimmer, 4 Hz 9015 in 2009 as its premium option, but the 8215 stayed in production as the budget workhorse.

For most of its life it didn't hack. Time+Tide reports that a stop-seconds feature was added from around 2019, and Miyota's current spec sheet lists a stop second device. That split explains a lot of contradictory advice online: whether your 8215 hacks depends on when it was made.

Accuracy in the real world

Miyota rates the 8215 at -20 to +40 seconds a day, with positional variation of up to 50 seconds. That's one of the widest official tolerances of any current movement, and it's the worst case for an unregulated movement.

Owner reports on watch forums are usually much better: a few seconds to around ten seconds fast a day is commonly reported, and some watches hold that for years. Results vary more than with a 9015, because many 8215 watches are sold without any regulation. The good news is that a watchmaker can usually tighten one up quickly and cheaply.

The 3 Hz beat means six ticks a second, so the seconds hand on a Timex Marlin looks steppier than a 4 Hz Swiss or 9015 watch. That's cosmetic, not a sign of poor timekeeping.

Reliability and servicing

Durability is the 8215's strongest point. It has been in production for nearly fifty years, watchmakers know it inside out, and it tolerates neglect well. Owners often describe watches that ran for a decade without attention.

• Replace rather than service. Time+Tide notes replacement movements can be found for as little as about $20. On an inexpensive watch, a new movement is usually cheaper than a full service.
• Watch for fakes. Clones marked "Miyota" circulate online. If you're buying a replacement, buy from a reputable parts supplier.
• Sentimental watches. Any competent watchmaker can strip and service the original if you'd rather keep it.

Quirks worth knowing

• Hacking depends on age. Older 8215s, and old-stock watches, don't stop the seconds hand when you pull the crown. That's normal, not a fault. Newer production does hack.
• Stuttering seconds hand. The central seconds is driven indirectly, and some 8215s show a slight hesitation or wobble in the seconds hand. It's a known trait.
• Rotor spin. The rotor winds one way and spins freely the other, which Time+Tide describes as a whizzing noise and an odd sensation on the wrist. It doesn't affect timekeeping.
• Thickness. At 5.67 mm it's much taller than the 9015's 3.9 mm, which is why 8215 watches often wear chunkier.
• Date setting. Avoid using the quickset late in the evening while the date is changing. Here's why.

How it compares

• Seiko NH35: the closest rival. Also 3 Hz with a 41-hour reserve, but it has always hacked, winds in both directions and has a tighter factory spec. Most owners call reliability a draw.
• Miyota 9015: the premium sibling. Same 42-hour reserve, but 4 Hz, much slimmer and with a tighter tolerance, at a higher cost.
• Orient F6922: similar class and reserve, adds a day display and hacks as standard, but it's found almost only in Orient watches.
• Seiko 7S26: the old Seiko 5 movement. Also non-hacking and no hand-winding, where older 8215s at least hand-wind.

Living with the 42-hour reserve

About 42 hours covers a night off the wrist, not a weekend. Take your Timex Marlin Automatic off at 6pm on Friday and it will stop around lunchtime on Sunday. Because the rotor only winds one way, a quiet day at a desk may leave it well short of full, so it can stop sooner than that.

If the Marlin or a Bulova automatic is one of several watches you wear, Watch Winder counts down the reserve for each watch you own and reminds you before it stops, so you can wear it or give it a few turns of the crown first. On an older non-hacking 8215, that saves you the fiddly job of setting the time to the second. For a one-off check, use the "Will my watch stop?" calculator.

Verdict

The Miyota 8215 isn't refined, but it's hard to kill. It's cheap, durable, easy to replace and usually far more accurate than its wide official spec suggests. The stutter, rotor spin, thickness and missing hacking on older units are real drawbacks if you care about finesse. In a Timex Marlin or a Bulova automatic, it does exactly what it has done since 1977: keeps going.

FAQ

How long does a Timex Marlin Automatic run off the wrist?

About 42 hours from a full wind, the Miyota 8215's rated reserve. If it was only partly wound, it will stop sooner.

Does the Timex Marlin Automatic hack?

Current Miyota 8215 production has a stop-seconds feature, added from around 2019. Older 8215 watches don't hack, which is normal for their age.

Why does my Bulova automatic's seconds hand stutter?

If it has a Miyota 8215, the indirectly driven seconds hand can hesitate slightly. It's a known trait of the movement, not a fault.

How accurate is the Miyota 8215?

Miyota's official spec is -20 to +40 seconds a day. Many owners report a few seconds to about ten seconds a day in practice.

Does the Citizen Tsuyosa use the Miyota 8215?

It uses Citizen's caliber 8210, a close relative in the same 82 family, with a 42-hour reserve and hacking.

Why did my Timex Marlin stop overnight?

It probably wasn't fully wound. The one-way rotor adds little on a quiet day, so give it 20 to 30 turns of the crown before you put it down.

Is the Miyota 8215 worth servicing?

On an inexpensive watch, replacing the movement is usually cheaper than a full service. On a watch you value, any competent watchmaker can service it.

Sources

• Miyota: Cal. 8215 specifications
• Time+Tide: Everything you need to know about Miyota
• Citizen: Tsuyosa NJ0150-56W product page
• Wikipedia: Miyota (watch movement manufacturer)

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 Miyota 8215. 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.

All Miyota 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 Miyota 8215: 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.