Movement names like 4R36, NH35 and 6R35 look like alphabet soup until you need to choose between two watches. This watch movement comparison puts 14 common automatic calibers side by side: power reserve, beat rate, hacking, hand-winding and rated accuracy, with the source for every number.
Compare watch movements side by side
Pick up to three. The newest pick replaces the oldest.
Full movement comparison table
| Movement | Jewels | Beat rate (vph) | Power reserve | Hacks | Hand-winds | Rated accuracy (s/day) |
|---|---|---|---|---|---|---|
| Seiko 4R36 | 24 | 21,600 | 41+ h | Yes | Yes | +45 / -35 |
| Seiko NH35A | 24 | 21,600 | 41 h | Yes | Yes | -20 / +40* |
| Seiko 7S26 | 21 | 21,600 | ~41 h | No | No | n/a |
| Seiko 6R15 | 23 | 21,600 | 50 h | Yes | Yes | +25 / -15 |
| Seiko 6R35 | 24 | 21,600 | ~70 h | Yes | Yes | +25 / -15 |
| Miyota 8215 | 21 | 21,600 | ~42 h | No | Yes | -20 / +40 |
| Miyota 9015 | 24 | 28,800 | ~42 h | Yes | Yes | -10 / +30 |
| ETA 2824-2 | 25 | 28,800 | 38 h | Yes | Yes | n/a |
| Sellita SW200 | 26 | 28,800 | 38 h | Yes | Yes | n/a |
| Vostok 2416B | 31 | 19,800 | ~31 h | n/c | n/c | -20 / +60 |
| Seiko 6309 (vintage) | 17 | 21,600 | 47 h | No | No | n/a |
| Seiko 7002 (vintage) | 17 | 21,600 | ~40–43 h | No | No | n/a |
| Seiko 6105B (vintage) | 17 | 21,600 | 46 h | Yes | n/c | n/a |
| Seiko 6139A (vintage) | 21 | 21,600 | 45 h | n/c | n/c | n/a |
n/a = no published figure in our sources. n/c = not confirmed by our sources. *Maker figure for the NH family.
What the numbers mean
- Power reserve is how long the watch runs once fully wound. Around 40 hours means it stops if you leave it overnight on Friday and pick it up on Sunday. 70 hours covers a weekend.
- Beat rate is how many times the balance swings per hour. 21,600 vph gives six ticks a second; 28,800 vph gives eight, so the seconds hand sweeps more smoothly.
- Hacking stops the seconds hand while you set the time. Useful if you like your watch synced to the second.
- Hand-winding lets you wind the watch through the crown, so a stopped watch starts without shaking.
- Rated accuracy is the maker’s tolerance for a new movement, not a promise for every watch. A serviced older movement can do much better or worse.
Vintage Seiko movements
The 6309, 7002, 6105 and 6139 power some of the most collected Seiko divers and chronographs. None of them were built with modern conveniences like hand-winding, so a vintage diver that has stopped needs a few minutes on the wrist or a gentle swirl. Each has a full guide in our vintage Seiko reference, and you can check whether a watch’s caseback numbers match its movement with the Seiko Franken Checker.
Which movement is in the watches we reviewed?
The Invicta 8926OB runs on the NH35A, so it hacks and hand-winds. The Vostok Amphibia uses the 2416B, an old-school 31-jewel automatic with a slower 19,800 vph beat. The Bulova 96A135 is an automatic too, while the Seiko SSB479 and Casio Duro are quartz.
Frequently asked questions
What is the difference between the Seiko 4R36 and NH35?
They are close relatives. The 4R36 is the version Seiko fits to its own watches, with a day and date. The NH35A is the date-only version Seiko’s movement arm sells to other brands. Both beat at 21,600 vph, hack, hand-wind and run for about 41 hours.
Is the 6R35 worth the upgrade over the 4R36?
If you take your watch off for a weekend, yes. The 6R35 runs for about 70 hours against roughly 41, and Seiko rates it tighter at +25 / -15 seconds a day against +45 / -35 for the 4R36.
What does hacking mean on a watch?
Hacking means the seconds hand stops when you pull the crown out, so you can set the time to the second. The 7S26 and vintage 6309 and 7002 do not hack.
Does a higher beat rate mean a better movement?
Not by itself. A 28,800 vph movement such as the Miyota 9015 or ETA 2824-2 gives a smoother sweep, and can be a little more stable when the watch is knocked. But a well-regulated 21,600 vph Seiko can keep excellent time and often runs longer between winds.
Can I hand-wind a Seiko 7S26 or SKX007?
No. The 7S26 is automatic only. Give it a gentle shake or wear it to get it going. Its successor, the 4R36, added hand-winding and hacking.
Sources
- Strapcode: caliber 4R36 and caliber 6R15
- Seiko 6R35 instruction manual and Caliber Corner 6R35
- Caliber Corner: 7S26, 6309, 7002A, NH36A
- Gear Patrol: common automatic movements (ETA 2824-2, SW200, NH35A, Miyota 9015)
- Rotate Watches: Miyota 8215 vs 9015
- Vostok-Watches24: 2416 movement and WatchScanning
- Ranfft: Seiko 6105B and 6139A