Seiko HDB004
Ref. HDB004 · In production
- Case42.5 mm
- Thick14.2 mm
- Lug-to-lug46 mm
- Water res.100 m
- MovementAutomatic
- CrystalHardlex (mineral)
Overview
The Seiko HDB004 is a sports watch from the Seiko 5 Sports collection, part of the SKX series family. It has a 42.5 mm stainless steel case, 14.2 mm thick, 46 mm from lug to lug. Inside is a automatic movement (calibre 4R36) with 41 h of power reserve. You also get 100 m water resistance, a hardlex (mineral) crystal and a bracelet.
Who it suits
- Wrists of roughly 17.0–18.9 cm (6.7–7.5 in), by our Watch Finder sizing guide
- Everyday wear including swimming
- People who enjoy seeing a mechanical movement at work
Strengths
- Compact 46 mm lug-to-lug suits smaller wrists
- Display caseback shows the movement
- Hacks and hand-winds, so it is easy to set
Trade-offs
- Hardlex (mineral) crystal scratches more easily than sapphire
- 41 h power reserve: it stops after about a day and a half off the wrist
- Thick at 14.2 mm: harder to slide under a cuff
Written by Watch.co from the published specs below. These are not owner reviews.
Full specifications
Case
| Case diameter | 42.5 mm | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Thickness | 14.2 mm | seikowatches.com · 23 Oct 2026 |
| Lug-to-lug | 46 mm | seikowatches.com · 23 Oct 2026 |
| Case material | Stainless steel | seikowatches.com · 23 Oct 2026 |
| Crystal | Hardlex (mineral) | seikowatches.com · 23 Oct 2026 |
| Caseback | Display (see-through) | seikowatches.com · 23 Oct 2026 |
| Bezel | Unidirectional rotating | seikowatches.com · 23 Oct 2026 |
| Water resistance | 100 m | seikowatches.com · 23 Oct 2026 |
| Magnetic resistance | 4,800 A/m | seikowatches.com · 23 Oct 2026 |
| Weight | 169 g | seikowatches.com · 23 Oct 2026 |
Dial
| Luminous material | LumiBrite | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Date | Day/Date | our classification |
Movement
| Movement type | Automatic | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Calibre | 4R36 | seikowatches.com · 23 Oct 2026 |
| Made in-house | Yes | seikowatches.com · 23 Oct 2026 |
| Power reserve | 41 h | seikowatches.com · 23 Oct 2026 |
| Hacking seconds | Yes | seikowatches.com · 23 Oct 2026 |
| Hand-winding | Yes | seikowatches.com · 23 Oct 2026 |
Strap / Bracelet
| Bracelet / strap | Bracelet | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Lug width | 22 mm | seikowatches.com · 23 Oct 2026 |
Other
| US list price (MSRP) | $400 | seikowatches.com · 23 Oct 2026 |
|---|---|---|
| Production status | In production | seikowatches.com · 23 Oct 2026 |
| Style (our classification) | Sports | our classification |
Specs are summarised in our own words from the brand's product page. Each row links its source and the date we checked it. Fields we haven't verified are left out rather than guessed.
Variants with the same specs
Same case, movement and bracelet or strap; typically a different dial or finish.
More in SKX series
Similar alternatives
Picked with Watch Finder's style tags and sizing.
Questions about the Seiko HDB004
How big is the Seiko HDB004?
The case is 42.5 mm wide, 14.2 mm thick and 46 mm from lug to lug.
What movement does the Seiko HDB004 use?
It uses the 4R36 calibre, a automatic movement with 41 h of power reserve.
Can I swim with the Seiko HDB004?
Yes. It is rated to 100 m.
Does the Seiko HDB004 have a date?
Yes, it shows the day and date.
How much is the Seiko HDB004?
The US list price was $400 on seikowatches.com when we checked on 23 Oct 2026. Prices change, so check before you buy.
Will the Seiko HDB004 fit my wrist?
By our sizing guide it sits best on wrists of about 17.0–18.9 cm (6.7–7.5 in). Use the fit checker on this page to test your own wrist.
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