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Movement · Seiko · automatic

Seiko 4R36 movement

Seiko 4R36 is an automatic movement by Seiko: 27.4 mm1secondary source across, 5.32 mm1secondary source high, 242 jewels, beating at 21,600 bph2, 41 h2 Sources disagree: manufacturer 41 h / secondary source 40, 41 h1 of power reserve. 49 watches in our base use it (list).

Sources checked · How we source numbers
Seiko 4R36: movement drawingSeiko 4R36, dial side, to scale: movement diameter 27.4 mm; date 3H window (size unknown); height 5.32 mm; hour, minute, second hand hole Ø — (unknown).movement Ø 27.4date 3Hsize —, position onlyØ 27.4 = 12.15‴5.32SIDE · SECTION · height 5.32Ahour, minute, second hand hole Ø —DETAIL A · 10:1
Seiko 4R36, dial sideDrawing from data, not a photo · mm

4R36 at a glance

Diameter
27.4 mm1secondary source
Height
5.32 mm1secondary source
Jewels
242
Beat rate
21,600 bph2
Power reserve
41 h2
2 sources disagree; show every value
  • manufacturer 41 h2
  • secondary source 40, 41 h1
Accuracy
−35 to +45 s/day3
Do not set the date
21:00–04:002

New to the terms? Read quartz vs automatic or watch movement types.

Setting and servicing the 4R36

The figures a watchmaker or a timegrapher needs for the 4R36, as Seiko prints them.

Accuracy (maker)
−35 to +45 s/day3only if worn on the wrist in a temperature range of 5°C to 35°C
Power reserve
41 h2
2 sources disagree; show every value
  • manufacturer 41 h2
  • secondary source 40, 41 h1
Do not set the date
21:00–04:002
Hacking seconds
Yes2
Hand winding
Yes2
Rotor winds
Bi-Directional Automatic Winding1secondary source

Watches with the 4R36

What fits the 4R36

The figures a dial, hands or case must match for the 4R36, as Seiko prints them.

Date window
3H1secondary source
  • The 4R36 is the same calibre as the NH36, sold under another name[1](secondary source).

Same family at Seiko

How each differs from the 4R36, worked out from the figures on its own page.

What can replace the 4R36

11 calibres of the Seiko NH / 4R / 7S group checked against the 4R36: diameter, height, hand holes, date window, crown and dial feet. A verdict marked “not confirmed” lacks one of those figures for the 4R36 or the other calibre.

Not published, so not checked in several comparisons:

  • hand holes for 4R36, 4R35, 4R34, 7S36 and NH38
  • crown position for 4R36, 4R35, 7S26, 4R34, 7S36 and NH38
  • dial feet for 4R36, 4R35, 7S26, 4R34, 7S36 and NH38

  1. 4R36 → NH36

    Drop-in· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • =dateDate window at 3H on both.

  2. 4R36 → 4R35

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠date4R35 has no day wheel: a day-date dial would show an empty day window.
    • =dateDate window at 3H on both.

  3. 4R36 → 7S26

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • ≠height7S26 is 0.42 mm thinner (4.9 mm vs 5.32 mm): the dial and hands sit lower, so a spacer or a different stem height may be needed.
    • =dateDate window at 3H on both.

  4. 4R36 → NH35

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠dateNH35 has no day wheel: a day-date dial would show an empty day window.
    • =dateDate window at 3H on both.

  5. 4R36 → 4R34

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • ≠functions4R34 adds a 24-hour hand: it needs a dial and hand set made for it.
    • ≠date4R34 has no day wheel: a day-date dial would show an empty day window.
    • =dateDate window at 3H on both.

    Not published, so not checked: height for 4R34.

  6. 4R36 → 7S36

    Fits with changes· not confirmed
    • ≠diameter7S36 is 0.4 mm narrower (movement diameter 27 mm vs 27.4 mm): it needs a movement ring or holder to sit centred.
    • ≠height7S36 is 0.52 mm thinner (4.8 mm vs 5.32 mm): the dial and hands sit lower, so a spacer or a different stem height may be needed.

    Not published, so not checked: date position for 7S36.

  7. 4R36 → NH34

    Fits with changes· not confirmed
    • =diameterAbout the same diameter (27.4 mm and 12‴; a size in lignes is rounded).
    • =heightSame height: 5.32 mm.
    • ≠functionsNH34 adds a 24-hour hand: it needs a dial and hand set made for it.
    • ≠dateNH34 has no day wheel: a day-date dial would show an empty day window.
    • =dateDate window at 3H on both.

    Not published, so not checked: a millimetre diameter for NH34.

  8. 4R36 → NH38

    Fits with changes· not confirmed
    • =diameterSame movement diameter: 27.4 mm.
    • =heightSame height: 5.32 mm.
    • ≠dateNH38 has no day wheel: a day-date dial would show an empty day window.
    • ≠dateNH38 has no date: a dial with a date window would show nothing in it.

3 more calibres in the group fit less well; compare any of them with the movement comparison.

All 4R36 figures

Every figure we hold for the 4R36, with its source. Where sources disagree, each value is shown.

Size

Diameter
27.4 mm1secondary source
Height
5.32 mm1secondary source

Running

Jewels
242
Beat rate
21,600 bph2
Power reserve
41 h2
2 sources disagree; show every value
  • manufacturer 41 h2
  • secondary source 40, 41 h1
Hands and functions
hours, minutes, centre seconds, date, day2
Hacking seconds
Yes2
Hand winding
Yes2
Rotor winds
Bi-Directional Automatic Winding1secondary source

Accuracy and care

Accuracy (maker)
−35 to +45 s/day3
Do not set the date
21:00–04:002

Fitting: dial, hands, stem

Date window
3H1secondary source

Origin

Made from
20101secondary source

Not published yet

  • Diameter: not published
  • Height: not published
  • Lift angle: not in the documents we read
  • Hand holes: not published by Seiko
  • Dial feet: not in the documents we read
  • Stem part number: not in the documents we read

4R36 questions

How accurate is the 4R36?

Seiko rates the 4R36 at −35 to +45 s/day, measured under Seiko’s own test conditions; a worn 4R36 can run outside the −35 to +45 s/day range.

Source [3][4][1]

Which watches use the 4R36?

49 watches in our base name the 4R36: SRP775, SRP777 Turtle, SRPA21, SRPC44, SRPD21, SRPD51 and 43 more.

How long does the 4R36 run when fully wound?

About 41 h from a full wind, per Seiko.

Source [2][3][1]

When should you not change the date on the 4R36?

Not between 21:00 and 04:00, per Seiko: the 4R36’s date change is engaged then, so move its hands past 04:00 before using the quick-set.

Source [2][3]

Does the 4R36 hack and hand-wind?

Yes, it hacks: the seconds hand stops with the crown pulled out. It can be wound by the crown.

Source [2][1][3]

Is the 4R36 the same as the NH36?

Sources describe the 4R36 and NH36 as the same calibre sold under two names. The 4R36 page shows Seiko’s own figures; the NH36 page shows TMI’s.

More on movements

Sources

Documents checked · Report a wrong number

  1. 1Grail Watch — Grail Watch Reference: Seiko Cal. 4R36 · 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. 4Seiko Watch Corporation — Instructions: Mechanical watch, Cal. 4R35 / 4R36 / 4R37 / 4R38 / 4R71 / 4R72 / 4R39 (English) · pdf · read
  5. 5Seiko Watch Corporation — SRP775 product page (Prospex), seikowatches.com ph-en · html · read
  6. 6WatchClicker — Seiko Turtle SRP777 Review - compared to SKX007 · html · read
  7. 7Seiko Watch Corporation — SRPA21 product page (Prospex), seikowatches.com ph-en · html · read
  8. 8WatchBase — SRPC44 Prospex Diver Turtle Goldtone, WatchBase database entry · html · read
  9. 9Seiko Watch Corporation — SRPD21 product page (Prospex), seikowatches.com global-en · html · read
  10. 10Seiko Watch Corporation — SRPD51 product page (us-en), seikowatches.com · html · read
  11. 11Seiko Watch Corporation — SRPD53 product page (us-en), seikowatches.com · html · read
  12. 12Seiko Watch Corporation — Automatic Diver's Watch instructions, Cal. 4R15/4R16/4R35/4R36/7S26/7S35/7S36 (English part, 2 pages) · pdf · read
  13. 13Seiko Watch Corporation — SRPD57 product page (5 Sports), seikowatches.com global-en (US page 404) · html · read
  14. 14Seiko Watch Corporation — SRPD59 product page (5 Sports), seikowatches.com US · html · read
  15. 15Seiko Watch Corporation — SRPD61 product page, seikowatches.com regional site (se-en) · html · read
  16. 16Seiko Watch Corporation — SRPD63 product page (us-en), seikowatches.com · html · read
  17. 17Seiko Watch Corporation — SRPD65 product page (us-en), seikowatches.com · html · read
  18. 18Seiko Watch Corporation — SRPD71 product page (5 Sports), seikowatches.com global-en (US page 404) · html · read