Brand · Watches
Seiko watches
We list 10 Seiko watches, from 38 to 42.5 mm and 0.2 lb to 0.4 lb. The lightest is the 5 Sports 24-Jewel Automatic Watch at 0.2 lb, and prices start at $252.
By Everyday LoadoutData checked seikousa.comAbout Seiko
- Watches listed
- 10
- Case range
- 38 to 42.5 mm
- Weight range
- 0.2 lb to 0.4 lb
- Price range
- $252 to $760
At a glance
Side-by-side specs
| Watch | Case | Thickness | Water | Movement | Crystal | From |
|---|---|---|---|---|---|---|
| Seiko 5 Sports 38mm Automatic Watch | 38 mm | 12.1 mm | 100 m | Automatic | — | $280 |
| Seiko Prospex Speedtimer Solar Chronograph | 39 mm | 13.3 mm | 100 m | Solar quartz | Sapphire | $725 |
| Seiko 5 Sports Automatic GMT Field Watch | 39.4 mm | 13.6 mm | 100 m | Automatic | — | $450 |
| Seiko 5 Sports 24-Jewel Automatic Watch | 40 mm | 13.5 mm | 100 m | Automatic | — | $252 |
| Seiko Prospex 42mm Samurai Automatic Diver | 41.7 mm | 12.3 mm | 200 m | Automatic | Mineral | $476 |
| Seiko Prospex Speedtimer Solar 1/100 second Ltd Ed Chronograph | 42 mm | 12.9 mm | 100 m | Solar quartz | Sapphire | $740 |
| Seiko Prospex Speedtimer Solar 1/100 second PVD Ltd Ed Chronograph | 42 mm | 12.9 mm | 100 m | Solar quartz | Sapphire | $760 |
| Seiko 5 Sports SKX Series | 42.5 mm | 13.9 mm | 100 m | Automatic | Mineral | $320 |
| Seiko 5 Sports Automatic GMT Watch | 42.5 mm | 13.5 mm | 100 m | Automatic | — | $380 |
| Seiko 5 Sports Automatic Watch | 42.5 mm | 13.4 mm | 100 m | Automatic | Mineral | $280 |
Image not availableColors: Vibrant Green Dial
The Seiko 5 Sports 38mm Automatic Watch is a 38 mm, 100 m water-resistant automatic dive watch. It runs on the Seiko 4R36, it measures 44.2 mm lug to lug and battery or power reserve: approximately 41-hour power reserve.
It's the third lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 38 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Not published
- Case material
- Stainless steel
- Weight
- 0.3 lb · 140 g
$280was $315at Long Island Watch, Vibrant Green Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Luminous hands and markers
- Rotating bezel
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableThe Seiko Prospex Speedtimer Solar Chronograph is a 39 mm, 100 m water-resistant solar quartz watch with a sapphire crystal. It runs on the Seiko Solar V192, it measures 45.5 mm lug to lug and battery or power reserve: 6-month power reserve.
It's the 6th lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 39 mm
- Water
- 100 m (328 ft)
- Movement
- Solar quartz
- Crystal
- Sapphire
- Case material
- Stainless steel
- Weight
- 0.4 lb · 161 g
$725at Long Island Watch, Pink Dial
Check price for the Seiko Prospex Speedtimer Solar Chronograph at Long Island Watch (opens in new tab)Full specs and sources for the Seiko Prospex Speedtimer Solar ChronographLowest in-stock price as of Oct 25, 2026.
Stands out
- Solar powered
- Sapphire crystal
- Luminous hands and markers
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableThe Seiko 5 Sports Automatic GMT Field Watch is a 39.4 mm, 100 m water-resistant automatic field watch. It runs on the Seiko 4R34, it measures 47.9 mm lug to lug and battery or power reserve: 41-hour power reserve.
It's the fourth lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 39.4 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Not published
- Case material
- Stainless steel
- Weight
- 0.3 lb · 147 g
$450at Long Island Watch
Check price for the Seiko 5 Sports Automatic GMT Field Watch at Long Island Watch (opens in new tab)Full specs and sources for the Seiko 5 Sports Automatic GMT Field WatchLowest in-stock price as of Oct 25, 2026.
Stands out
- Luminous hands and markers
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableThe Seiko 5 Sports 24-Jewel Automatic Watch is a 40 mm, 100 m water-resistant automatic watch. It runs on the Seiko 4R36 and it measures 48 mm lug to lug.
It's the lightest of the 10 watches here, 94 g lighter than the heaviest and the least expensive here at $252. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 40 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Not published
- Case material
- Stainless steel
- Weight
- 0.2 lb · 78 g
$252was $284at Long Island Watch, Dark Blue Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Luminous hands and markers
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Seiko Prospex 42mm Samurai Automatic Diver
Most water resistant
Image not availableThe Seiko Prospex 42mm Samurai Automatic Diver is a 41.7 mm, 200 m water-resistant automatic dive watch with a mineral crystal. It runs on the Seiko 23-Jewel 4R35 and it measures 49.5 mm lug to lug.
It's the 8th lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 41.7 mm
- Water
- 200 m (656 ft)
- Movement
- Automatic
- Crystal
- Mineral
- Case material
- Stainless steel
- Weight
- 0.4 lb · 170 g
$476was $536at Long Island Watch, Red Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableColors: Brown Dial
The Seiko Prospex Speedtimer Solar 1/100 second Ltd Ed Chronograph is a 42 mm, 100 m water-resistant solar quartz watch with a sapphire crystal. It runs on the Seiko Solar 8A50, it measures 48.3 mm lug to lug and battery or power reserve: 6-month power reserve when fully charged.
It's the fifth lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 42 mm
- Water
- 100 m (328 ft)
- Movement
- Solar quartz
- Crystal
- Sapphire
- Case material
- Stainless steel
- Weight
- 0.3 lb · 152 g
$740was $833at Long Island Watch, Brown Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Solar powered
- Sapphire crystal
- Luminous hands and markers
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableColor not published
The Seiko Prospex Speedtimer Solar 1/100 second PVD Ltd Ed Chronograph is a 42 mm, 100 m water-resistant solar quartz watch with a sapphire crystal. It runs on the Seiko Solar 8A50, it measures 48.3 mm lug to lug and battery or power reserve: 6-month power reserve when fully charged.
It's the 5th lightest of the 10 watches here and the most expensive here at $760. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 42 mm
- Water
- 100 m (328 ft)
- Movement
- Solar quartz
- Crystal
- Sapphire
- Case material
- Stainless steel
- Weight
- 0.3 lb · 152 g
$760was $855at Long Island Watch
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Solar powered
- Sapphire crystal
- Luminous hands and markers
- 20 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableThe Seiko 5 Sports SKX Series is a 42.5 mm, 100 m water-resistant automatic watch with a mineral crystal. It runs on the Seiko 4R36 and it measures 46 mm lug to lug.
It's the second lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 42.5 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Mineral
- Case material
- Stainless steel
- Weight
- 0.2 lb · 100 g
$320was $360at Long Island Watch, Yellow Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- 22 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableThe Seiko 5 Sports Automatic GMT Watch is a 42.5 mm, 100 m water-resistant automatic watch. It runs on the Seiko 4R34 and it measures 46 mm lug to lug.
It's the 7th lightest of the 10 watches here. Worth knowing: sold by one retailer we track (Long Island Watch).
- Case
- 42.5 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Not published
- Case material
- Stainless steel
- Weight
- 0.4 lb · 161 g
$380was $428at Long Island Watch, Brown Dial
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Rotating bezel
- 22 mm lugs
Worth knowing
- Sold by one retailer we track (Long Island Watch)
Image not availableColors: Blue Dial and Pepsi Bezel
The Seiko 5 Sports Automatic Watch is a 42.5 mm, 100 m water-resistant automatic watch with a mineral crystal. It runs on the Seiko 4R36 and it measures 46 mm lug to lug.
At 0.4 lb it's the heaviest of the 10 watches here. Worth knowing: heaviest watch in this list.
- Case
- 42.5 mm
- Water
- 100 m (328 ft)
- Movement
- Automatic
- Crystal
- Mineral
- Case material
- Stainless steel
- Weight
- 0.4 lb · 172 g
$280was $315at Long Island Watch, Blue Dial and Pepsi Bezel
Lowest in-stock price as of Oct 25, 2026.
Stands out
- Luminous hands and markers
- Rotating bezel
- 22 mm lugs
Worth knowing
- Heaviest watch in this list
- Sold by one retailer we track (Long Island Watch)
Questions, answered from the data
What are the lightest Seiko watches?
The Seiko 5 Sports 24-Jewel Automatic Watch is the lightest at 0.2 lb (78 g), by Long Island Watch's listing.
What's the cheapest option?
The Seiko 5 Sports 24-Jewel Automatic Watch, with a lowest in-stock price of $252 this week.
Which are solar powered?
The Seiko Prospex Speedtimer Solar Chronograph, the Seiko Prospex Speedtimer Solar 1/100 second Ltd Ed Chronograph and the Seiko Prospex Speedtimer Solar 1/100 second PVD Ltd Ed Chronograph are light-powered.
Which is the most water resistant?
The Seiko Prospex 42mm Samurai Automatic Diver, rated to 200 m (656 ft).
About this list
This page includes every Seiko watch in our database, ordered by case. “At a glance” picks compare these watches with each other only. To compare across brands, use the watch search.
Specs come from Seiko’s product pages unless marked otherwise, and every value links to its source on the product page. Prices are the lowest in-stock price we found on Oct 25, 2026. This is a spec comparison, not a hands-on review. Read our methodology.