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Seiko watch · Presage · automatic

Seiko SSA345

The Seiko SSA345 measures 40 mm across and 12 mm thick, with 20 mm lugs.

Sources checked · How we source numbers
Case
40 mm1
Lug to lug
not published
Thickness
12 mm1
Lug width
20 mm1
Seiko SSA345: size drawingSeiko SSA345, round case, top and side view to scale: case diameter 40 mm, lug to lug — (unknown), lug width 20 mm, thickness 12 mm. Bezel, dial and crown size are schematic.lug width 20Ø 40lug to lug —TOPthickness 12SIDE
Seiko SSA345, top and side, to scaleDrawing from data, not a photo · mm

Seiko SSA345 specifications

Case diameter
40 mm1seller listing
Lug to lug
not published
Thickness
12 mm1seller listing
Lug width
20 mm1seller listing20 mm watches
Crystal
Mineral glass1seller listing
Water resistance
50 m1seller listing
Movement
Seiko 4R571seller listing · automaticSeiko 4R57 specs
Battery
none: the Seiko 4R57 is automatic
Years made
start not published
Case code
not in our data yet

On your wrist

No lug-to-lug or case length is published for the Seiko SSA345, so there is no fit verdict yet.

Actual size on your screen

Calibrate once with a bank card and the drawing shows the Seiko SSA345 at 1:1, next to a millimetre ruler.

1:1 · not calibrated: sizes are approximate
Seiko SSA345: size drawingSeiko SSA345, round case, top and side view to scale: case diameter 40 mm, lug to lug — (unknown), lug width 20 mm, thickness 12 mm. Bezel, dial and crown size are schematic.lug width 20Ø 40lug to lug —TOPthickness 12SIDE
Drawing from data, not a photo · mm
01020304050

Seiko SSA345 strap size

Lug width 20 mm1seller listing: a 20 mm strap with 20 mm spring bars fits between the lugs. 62 other models take 20 mm.

Attachment: not published in our sources.

Find your strap length in the watch strap size tool, with the Seiko SSA345 filled in.

On a bracelet? How to remove watch links to size it to your wrist.

20 mm strap: strap diagramTwo-piece strap laid flat (20 mm strap). Lug width 20 mm. Short piece — (unknown), long piece — (unknown). Buckle, keepers and holes are schematic.short —long —lug 20lug 20strap length —20 mm strap
20 mm at the lugs; lengths depend on your wristDrawing from data, not a photo · mm

Movement: Seiko 4R57

The Seiko SSA345 runs on the Seiko 4R57, an automatic movement. 2 other models in our base use it.

Beat rate
21,600 bph2
Power reserve
41 h2
Jewels
292
Hacking seconds
Yes2
Hand winding
Yes2

Battery

none: the Seiko 4R57 is automatic

A mechanical watch has no cell to replace; it needs a service instead.

Same size as the Seiko SSA345

Same movement: Seiko 4R57

Seiko SSA345 questions

Does the Seiko SSA345 need a battery?

No. The Seiko SSA345 has no cell to replace: a wound mainspring drives its automatic Seiko 4R57.

What movement is in the Seiko SSA345?

The Seiko SSA345 runs on the Seiko 4R57, an automatic movement.

What strap size does the Seiko SSA345 take?

The Seiko SSA345 measures 20 mm between the lugs, so it takes a 20 mm strap with 20 mm spring bars. 62 other models in our base share that width.

Find the strap length for your wrist and the Seiko SSA345 in the watch strap size tool.

More Seiko watches

Sources

Documents checked · Report a wrong number

  1. 1Right Time International — SSA345 listing, Right Time (Denver), dealer spec block (pre-owned listing, sold out 6/2025) · html · read
  2. 2Seiko Watch Corporation — Instructions: SEIKO Automatic Watch Cal. 4R57 (English/multilingual booklet) · pdf · read