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Seiko watch · Prospex · automatic

Seiko SPB157

The Seiko SPB157 measures 38 mm across, 46 mm lug to lug, and 12.9 mm thick, with 20 mm lugs. It fits wrists from ~16.5 cm (flat-fit estimate).

Sources checked · How we source numbers
Case
38 mm1
Lug to lug
46 mm1
Thickness
12.9 mm1
Lug width
20 mm1
Seiko SPB157: size drawingSeiko SPB157, round case, top and side view to scale: case diameter 38 mm, lug to lug 46 mm, lug width 20 mm, thickness 12.9 mm. Bezel, dial and crown size are schematic.lug width 20Ø 38lug to lug 46TOPthickness 12.9SIDE
Seiko SPB157, top and side, to scaleDrawing from data, not a photo · mm

Seiko SPB157 specifications

Case diameter
38 mm1
Lug to lug
46 mm1
Thickness
12.9 mm1
Lug width
20 mm120 mm watches
Weight
85 g1
Crystal
Curved sapphire crystal1
Water resistance
20 bar (200 m)1
Movement
Seiko 6R351 · automaticSeiko 6R35 specs
Battery
none: the Seiko 6R35 is automatic
Years made
start not published
Case code
not in our data yet

On your wrist

The verdict compares the lug to lug with the flat top of your wrist. Balanced from ~16.5 cm, past the edges below ~14.5 cm.

= 6.7 in

Balanced on a 17 cm wrist: the 46 mm lug to lug covers 84% of an estimated 54.8 mm flat top.

Flat top = circumference ÷ 3.1, a community convention, not a measurement of your arm. Compact ≤ 0.75 of the flat top, balanced ≤ 0.89, at the edge ≤ 1. Compare more watches in the watch size calculator.

Seiko SPB157: wrist fitSeiko SPB157 on a wrist, top view to scale. lug to lug 46 mm. Wrist 170 mm, estimated flat width 54.8 mm (circumference / 3.1). Ratio 0.84: balanced.wrist, flat topwrist flat ≈ 54.8lug to lug 46Balanced · 46 / 54.8 = 0.84estimate: wrist 170 / 3.1 = 54.8 flatcompactbalancededgeoverhang0.750.891
Seiko SPB157 on a 17 cm wristDrawing from data, not a photo · mm

Actual size on your screen

Calibrate once with a bank card and the drawing shows the Seiko SPB157 at 1:1, next to a millimetre ruler.

1:1 · not calibrated: sizes are approximate
Seiko SPB157: size drawingSeiko SPB157, round case, top and side view to scale: case diameter 38 mm, lug to lug 46 mm, lug width 20 mm, thickness 12.9 mm. Bezel, dial and crown size are schematic.lug width 20Ø 38lug to lug 46TOPthickness 12.9SIDE
Drawing from data, not a photo · mm
01020304050

Seiko SPB157 strap size

Lug width 20 mm1: 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 SPB157 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 6R35

The Seiko SPB157 runs on the Seiko 6R35, an automatic movement. 17 other models in our base use it.

Beat rate
21,600 bph2
Power reserve
70 h2
Jewels
242
Accuracy
−15 to +25 s/day2
Hacking seconds
Yes2
Hand winding
Yes2

Battery

none: the Seiko 6R35 is automatic

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

Same size as the Seiko SPB157

The models nearest to the Seiko SPB157 in case width and lug to lug, drawn over it to scale; below, every model within 1 mm of its 46 mm.

Size comparison: Seiko SPB157, Seiko SPB241, Seiko SPB245, Seiko SPB249Top-view outlines to scale on one centre. A Seiko SPB157: Ø 38, L2L 46, lug 20, T 12.9. B Seiko SPB241: Ø 38, L2L 46.2, lug 19, T 12.9 (vs A: Ø 0 L2L +0.2 lug −1 T 0). C Seiko SPB245: Ø 38, L2L 46.2, lug 19, T 12.9 (vs A: Ø 0 L2L +0.2 lug −1 T 0). D Seiko SPB249: Ø 38, L2L 46.2, lug 19, T 12.9 (vs A: Ø 0 L2L +0.2 lug −1 T 0).A Ø 38B Ø 38C Ø 38D Ø 38A L2L 46B L2L 46.2C L2L 46.2D L2L 46.2A Seiko SPB157Ø 38 · L2L 46 · lug 20 · T 12.9B Seiko SPB241Ø 38 · L2L 46.2 · lug 19 · T 12.9vs A: Ø 0 L2L +0.2 lug −1 T 0C Seiko SPB245Ø 38 · L2L 46.2 · lug 19 · T 12.9vs A: Ø 0 L2L +0.2 lug −1 T 0D Seiko SPB249Ø 38 · L2L 46.2 · lug 19 · T 12.9vs A: Ø 0 L2L +0.2 lug −1 T 0
A Seiko SPB157 and the 3 nearest in size, on one centre, to scaleDrawing from data, not a photo · mm

Nearest in size

  1. ASeiko SPB157this watch
  2. BSeiko SPB241W same · L2L +0.2 · T same mm
  3. CSeiko SPB245W same · L2L +0.2 · T same mm
  4. DSeiko SPB249W same · L2L +0.2 · T same mm

Differences against A in mm: W case width, L2L lug to lug, T thickness. Nearest by width and length together, from the published sizes.

Same published case dimensions (2)Seiko SPB155, Seiko SPB159

Same movement: Seiko 6R35

All 18 models on the Seiko 6R35

Seiko SPB157 questions

How big is the Seiko SPB157?

The Seiko SPB157 measures 38 mm across, 46 mm lug to lug, 12.9 mm thick, 85 g.

Will the Seiko SPB157 fit a 6.5-inch wrist?

Balanced: the Seiko SPB157's 46 mm lug to lug takes 86% of the ~53.3 mm flat top of a 6.5-inch (16.5 cm) wrist. By the same estimate (circumference ÷ 3.1) it sits balanced from about 16.5 cm and overhangs the flat top on wrists under about 14.5 cm.

Does the Seiko SPB157 need a battery?

No. The Seiko SPB157 has no cell to replace: a wound mainspring drives its automatic Seiko 6R35.

What movement is in the Seiko SPB157?

The Seiko SPB157 runs on the Seiko 6R35, an automatic movement.

What strap size does the Seiko SPB157 take?

The Seiko SPB157 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 SPB157 in the watch strap size tool.

More Seiko watches

Sources

Documents checked · Report a wrong number

  1. 1Seiko Watch Corporation — SPB157J1 product page (Prospex), seikowatches.com global-en · html · read
  2. 2Seiko Watch Corporation — Diver's watch for air diving instructions, Cal. 6R35 (EN) · pdf · read
  3. 3CaliberCorner — Seiko Caliber 6R35 watch movement page · html · read
  4. 4Grail Watch — Grail Watch Reference: Seiko 6R35 · html · read