Seiko Cal. 6R24 is a midrange automatic movement produced by Seiko Instruments Inc. (SII) for Seiko watches. Like other Seiko 6R movements, it is more refined and accurate than the related Seiko 4R series and uses a Spron 510 mainspring. Unlike Cal. 6R15, it is a “Hi-Beat” movement operating at 28,800 A/h and has complications: Retrograde day at 2:30, retrograde date at 6:00, and retrograde power reserve at 9:30.
Cal. 6R24 was introduced around 2009 and remains in production today. It has 31 jewels and 224 parts. Cal. 6R24 was used in the Ananta Double Retrograde Automatic watches, models SPB013J1 and SPB015J1, produced August 2009 through July 2012.
According to Seiko documents, this is a modular movement based on Cal. 6R15 but with a Hi-Beat balance and hacking seconds.
| Jewels | Components | Speed | Power | 3:00 | 6:00 | 9:00 | |
| 6R15 | 23 | 168 | 21,600 | 50 | Date Window | ||
| 6R20 | 29 | 208 | 28,800 | 45 | Day Subdial | Date Subdial | Clockwise Power Reserve |
| 6R21 | 29 | 208 | 28,800 | 45 | Day Subdial | Date Subdial | Counter-Clockwise Power Reserve |
| 6R24 | 31 | 224 | 28,800 | 45 | Retrograde Day | Retrograde Date | Clockwise Power Reserve |
| 6R27 | 29 | 28,800 | 45 | Date Subdial | Counter-Clockwise Power Reserve | ||
| 6R35 | 24 | 21,600 | 70 | Date Window |