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Seiko watch · Prospex · automatic

Seiko SRPE37

The Seiko SRPE37 measures 43.8 mm across, 48.7 mm lug to lug, and 12.8 mm thick, with 22 mm lugs. It fits wrists from ~17 cm (flat-fit estimate).

Sources checked · How we source numbers
Case
43.8 mm1
Lug to lug
48.7 mm1
Thickness
12.8 mm1
Lug width
22 mm1
Seiko SRPE37: size drawingSeiko SRPE37, round case, top and side view to scale: case diameter 43.8 mm, lug to lug 48.7 mm, lug width 22 mm, thickness 12.8 mm, rotating bezel. Bezel, dial and crown size are schematic.lug width 22Ø 43.8lug to lug 48.7TOPthickness 12.8SIDE
Seiko SRPE37, top and side, to scaleDrawing from data, not a photo · mm

Seiko SRPE37 specifications

Case diameter
43.8 mm1
Lug to lug
48.7 mm1
Thickness
12.8 mm1
Lug width
22 mm122 mm watches
Weight
126 g1
Crystal
Sapphire crystal1
Water resistance
200 m1
Movement
Seiko 4R351 · automaticSeiko 4R35 specs
Battery
none: the Seiko 4R35 is automatic
Years made
start not published
Case code
not in our data yet
Bezel
unidirectional rotating1
Line
Prospex1

On your wrist

The verdict compares the lug to lug with the flat top of your wrist. Balanced from ~17 cm, past the edges below ~15.5 cm.

= 6.7 in

Balanced on a 17 cm wrist: the 48.7 mm lug to lug covers 89% 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 SRPE37: wrist fitSeiko SRPE37 on a wrist, top view to scale. lug to lug 48.7 mm. Wrist 170 mm, estimated flat width 54.8 mm (circumference / 3.1). Ratio 0.89: balanced.wrist, flat topwrist flat ≈ 54.8lug to lug 48.7Balanced · 48.7 / 54.8 = 0.89estimate: wrist 170 / 3.1 = 54.8 flatcompactbalancededgeoverhang0.750.891
Seiko SRPE37 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 SRPE37 at 1:1, next to a millimetre ruler.

1:1 · not calibrated: sizes are approximate
Seiko SRPE37: size drawingSeiko SRPE37, round case, top and side view to scale: case diameter 43.8 mm, lug to lug 48.7 mm, lug width 22 mm, thickness 12.8 mm, rotating bezel. Bezel, dial and crown size are schematic.lug width 22Ø 43.8lug to lug 48.7TOPthickness 12.8SIDE
Drawing from data, not a photo · mm
01020304050

Seiko SRPE37 strap size

Lug width 22 mm1: a 22 mm strap with 22 mm spring bars fits between the lugs. 45 other models take 22 mm.

Attachment: not published in our sources.

Find your strap length in the watch strap size tool, with the Seiko SRPE37 filled in.

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

22 mm strap: strap diagramTwo-piece strap laid flat (22 mm strap). Lug width 22 mm. Short piece — (unknown), long piece — (unknown). Buckle, keepers and holes are schematic.short —long —lug 22lug 22strap length —22 mm strap
22 mm at the lugs; lengths depend on your wristDrawing from data, not a photo · mm

Movement: Seiko 4R35

The Seiko SRPE37 runs on the Seiko 4R35, an automatic movement. 25 other models in our base use it.

Beat rate
21,600 bph2
Power reserve
41 h2
2 sources disagree; show every value
  • manufacturer 41 h2
  • secondary source 40, 41 h4
Jewels
232
2 sources disagree; show every value
  • manufacturer 232
  • secondary source 23, 244
Accuracy
−35 to +45 s/day3
Hacking seconds
Yes2
Hand winding
Yes2

Battery

none: the Seiko 4R35 is automatic

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

Same size as the Seiko SRPE37

The models nearest to the Seiko SRPE37 in case width and lug to lug, drawn over it to scale; below, every model within 1 mm of its 48.7 mm.

Size comparison: Seiko SRPE37, Seiko SRPD23, Casio MDV-106, Seiko SLA077J1Top-view outlines to scale on one centre. A Seiko SRPE37: Ø 43.8, L2L 48.7, lug 22, T 12.8. B Seiko SRPD23: Ø 43.8, L2L 48.4, lug 22, T 13.4 (vs A: Ø 0 L2L −0.3 lug 0 T +0.6). C Casio MDV-106: Ø 44.2, L2L 48, lug 22, T 12.1 (vs A: Ø +0.4 L2L −0.7 lug 0 T −0.7). D Seiko SLA077J1: Ø 42.6, L2L 49.3, lug 20, T 13.4 (vs A: Ø −1.2 L2L +0.6 lug −2 T +0.6).D Ø 42.6A Ø 43.8B Ø 43.8C Ø 44.2C L2L 48B L2L 48.4A L2L 48.7D L2L 49.3A Seiko SRPE37Ø 43.8 · L2L 48.7 · lug 22 · T 12.8B Seiko SRPD23Ø 43.8 · L2L 48.4 · lug 22 · T 13.4vs A: Ø 0 L2L −0.3 lug 0 T +0.6C Casio MDV-106Ø 44.2 · L2L 48 · lug 22 · T 12.1vs A: Ø +0.4 L2L −0.7 lug 0 T −0.7D Seiko SLA077J1Ø 42.6 · L2L 49.3 · lug 20 · T 13.4vs A: Ø −1.2 L2L +0.6 lug −2 T +0.6
A Seiko SRPE37 and the 3 nearest in size, on one centre, to scaleDrawing from data, not a photo · mm

Nearest in size

  1. ASeiko SRPE37this watch
  2. BSeiko SRPD23W same · L2L −0.3 · T +0.6 mm
  3. CCasio MDV-106W +0.4 · L2L −0.7 · T −0.7 mm
  4. DSeiko SLA077J1W −1.2 · L2L +0.6 · T +0.6 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 SRPE33, Seiko SRPF79

Same movement: Seiko 4R35

All 26 models on the Seiko 4R35

Seiko SRPE37 questions

How big is the Seiko SRPE37?

The Seiko SRPE37 measures 43.8 mm across, 48.7 mm lug to lug, 12.8 mm thick, 126 g.

Will the Seiko SRPE37 fit a 7-inch wrist?

Balanced: the Seiko SRPE37's 48.7 mm lug to lug takes 85% of the ~57.4 mm flat top of a 7-inch (17.8 cm) wrist. By the same estimate (circumference ÷ 3.1) it sits balanced from about 17 cm and overhangs the flat top on wrists under about 15.5 cm.

Does the Seiko SRPE37 need a battery?

No. The Seiko SRPE37 has no cell to replace: a wound mainspring drives its automatic Seiko 4R35.

What movement is in the Seiko SRPE37?

The Seiko SRPE37 runs on the Seiko 4R35, an automatic movement.

What strap size does the Seiko SRPE37 take?

The Seiko SRPE37 measures 22 mm between the lugs, so it takes a 22 mm strap with 22 mm spring bars. 45 other models in our base share that width.

Find the strap length for your wrist and the Seiko SRPE37 in the watch strap size tool.

More Seiko watches

Sources

Documents checked · Report a wrong number

  1. 1Seiko Watch Corporation — SRPE37 product page (Prospex), seikowatches.com US · html · read
  2. 2Seiko Watch Corporation — Instructions: Seiko Automatic Diver's Watch Cal. 4R15/4R16/4R35/4R36/7S26/7S35/7S36 (English) · pdf · read
  3. 3Seiko Watch Corporation — Instructions: Diver's Watch for Air Diving, Cal. 4R35 / 4R36 (English) · pdf · read
  4. 4Grail Watch — Grail Watch Reference: Seiko Cal. 4R35 · html · read
  5. 5Seiko Watch Corporation — Instructions: Mechanical watch, Cal. 4R35 / 4R36 / 4R37 / 4R38 / 4R71 / 4R72 / 4R39 (English) · pdf · read