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Seiko watch · Prospex · automatic

Seiko SRPF77

The Seiko SRPF77 measures 45 mm across, 47.7 mm lug to lug, and 13.2 mm thick, with 22 mm lugs. It fits wrists from ~17 cm (flat-fit estimate).

Sources checked · How we source numbers
Case
45 mm1
Lug to lug
47.7 mm1
Thickness
13.2 mm1
Lug width
22 mm1
Seiko SRPF77: size drawingSeiko SRPF77, round case, top and side view to scale: case diameter 45 mm, lug to lug 47.7 mm, lug width 22 mm, thickness 13.2 mm, rotating bezel. Bezel, dial and crown size are schematic.lug width 22Ø 45lug to lug 47.7TOPthickness 13.2SIDE
Seiko SRPF77, top and side, to scaleDrawing from data, not a photo · mm

Seiko SRPF77 specifications

Case diameter
45 mm1
Lug to lug
47.7 mm1
Thickness
13.2 mm1
Lug width
22 mm122 mm watches
Weight
128 g1
Crystal
Sapphire crystal with magnifier1
Water resistance
200 m1
Movement
Seiko 4R361 · automaticSeiko 4R36 specs
Battery
none: the Seiko 4R36 is automatic
Years made
start not published
Case code
not in our data yet
Bezel
unidirectional rotating1

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 cm.

= 6.7 in

Balanced on a 17 cm wrist: the 47.7 mm lug to lug covers 87% 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 SRPF77: wrist fitSeiko SRPF77 on a wrist, top view to scale. lug to lug 47.7 mm. Wrist 170 mm, estimated flat width 54.8 mm (circumference / 3.1). Ratio 0.87: balanced.wrist, flat topwrist flat ≈ 54.8lug to lug 47.7Balanced · 47.7 / 54.8 = 0.87estimate: wrist 170 / 3.1 = 54.8 flatcompactbalancededgeoverhang0.750.891
Seiko SRPF77 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 SRPF77 at 1:1, next to a millimetre ruler.

1:1 · not calibrated: sizes are approximate
Seiko SRPF77: size drawingSeiko SRPF77, round case, top and side view to scale: case diameter 45 mm, lug to lug 47.7 mm, lug width 22 mm, thickness 13.2 mm, rotating bezel. Bezel, dial and crown size are schematic.lug width 22Ø 45lug to lug 47.7TOPthickness 13.2SIDE
Drawing from data, not a photo · mm
01020304050

Seiko SRPF77 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 SRPF77 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 4R36

The Seiko SRPF77 runs on the Seiko 4R36, an automatic movement. 47 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
242
Accuracy
−35 to +45 s/day3
Hacking seconds
Yes2
Hand winding
Yes2

Battery

none: the Seiko 4R36 is automatic

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

Same size as the Seiko SRPF77

The models nearest to the Seiko SRPF77 in case width and lug to lug, drawn over it to scale; below, every model within 1 mm of its 47.7 mm.

Size comparison: Seiko SRPF77, Seiko SRP777, Casio MDV-106, Seiko SRPD23Top-view outlines to scale on one centre. A Seiko SRPF77: Ø 45, L2L 47.7, lug 22, T 13.2. B Seiko SRP777: W 45, L2L 48, lug 22, T 14 (vs A: W 0 L2L +0.3 lug 0 T +0.8). C Casio MDV-106: Ø 44.2, L2L 48, lug 22, T 12.1 (vs A: Ø −0.8 L2L +0.3 lug 0 T −1.1). D Seiko SRPD23: Ø 43.8, L2L 48.4, lug 22, T 13.4 (vs A: Ø −1.2 L2L +0.7 lug 0 T +0.2).D Ø 43.8C Ø 44.2A Ø 45B W 45A L2L 47.7B L2L 48C L2L 48D L2L 48.4A Seiko SRPF77Ø 45 · L2L 47.7 · lug 22 · T 13.2B Seiko SRP777W 45 · L2L 48 · lug 22 · T 14vs A: W 0 L2L +0.3 lug 0 T +0.8C Casio MDV-106Ø 44.2 · L2L 48 · lug 22 · T 12.1vs A: Ø −0.8 L2L +0.3 lug 0 T −1.1D Seiko SRPD23Ø 43.8 · L2L 48.4 · lug 22 · T 13.4vs A: Ø −1.2 L2L +0.7 lug 0 T +0.2
A Seiko SRPF77 and the 3 nearest in size, on one centre, to scaleDrawing from data, not a photo · mm

Nearest in size

  1. ASeiko SRPF77this watch
  2. BSeiko SRP777W same · L2L +0.3 · T +0.8 mm
  3. CCasio MDV-106W −0.8 · L2L +0.3 · T −1.1 mm
  4. DSeiko SRPD23W −1.2 · L2L +0.7 · T +0.2 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 (3)Seiko SRPE03, Seiko SRPE05, Seiko SRPG19

Same movement: Seiko 4R36

All 48 models on the Seiko 4R36

Seiko SRPF77 questions

How big is the Seiko SRPF77?

The Seiko SRPF77 measures 45 mm across, 47.7 mm lug to lug, 13.2 mm thick, 128 g.

Will the Seiko SRPF77 fit a 7-inch wrist?

Balanced: the Seiko SRPF77's 47.7 mm lug to lug takes 83% 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 cm.

Does the Seiko SRPF77 need a battery?

No. The Seiko SRPF77 has no cell to replace: a wound mainspring drives its automatic Seiko 4R36.

What movement is in the Seiko SRPF77?

The Seiko SRPF77 runs on the Seiko 4R36, an automatic movement.

What strap size does the Seiko SRPF77 take?

The Seiko SRPF77 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 SRPF77 in the watch strap size tool.

More Seiko watches

Sources

Documents checked · Report a wrong number

  1. 1Seiko Watch Corporation — SRPF77 product page (Prospex), seikowatches.com us-en · 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. 4R36 · html · read
  5. 5Seiko Watch Corporation — Instructions: Mechanical watch, Cal. 4R35 / 4R36 / 4R37 / 4R38 / 4R71 / 4R72 / 4R39 (English) · pdf · read