Yep, Blu-rays can store something like 25GB per layer; industry standard for movies is dual layer (50GB).
Rips can achieve comparable quality with lower bitrate than used on the original disk. Blu-ray dates to 2006 and (typically) uses inefficient high bit-rate H.262 ("MPEG 2", which DVDs used), H.264 (AVC), or VC-1.
Rips can use high-efficiency H.265 ("HEVC"). Typical for a 1080p H.265 encoding is 9-15 GB. (Lower for animated films.)
UHD Blu-rays do use the more efficient H.265 already, but are much higher resolution as well. I'm not sure how prevalent they are.
The vast majority of newer Blurays use H.264, which is pretty efficient (much more than the other two). In addition, if you're just wanting to back up the film, and not any special features on the disk, at least half of films fit in 25 GB with no reencoding required.
One big downside of reencoding in HEVC is that for a moderate gain in compression (0-50% depending on the film), you considerably increase your playback requirements. I use a Raspberry Pi 3 with Kodi as a playback device, and it's not capable of playing 1080p HEVC videos.
UHD Blurays are getting more common. They usually come on 66 GiB disks, and it's becoming more common to let the video take up most of that, and bundling a second disk of special features if necessary. So even backing up the main feature of a UHD can easily run you 50+ GiB.
> The vast majority of newer Blurays use H.264, which is pretty efficient (much more than the other two).
Right; still quite a bit less efficient than H.265, though.
> One big downside of reencoding in HEVC is that for a moderate gain in compression (0-50% depending on the film), you considerably increase your playback requirements.
Yes, although this is becoming less true as more hardware offload support becomes available.
For example, Nvidia 750, 950-960, and 1030 are all capable of HEVC offload[1]. The latter can be had new for ~$85; the others are probably a bit harder to find but given they're older midrange cards at this point maybe they're a little cheaper.
> So even backing up the main feature of a UHD can easily run you 50+ GiB.
Sure, I don't think there's any economical way to reduce storage requirements of UHD significantly without defeating the point. On the other hand, I don't think the extra pixels really matter as much as higher color depth (10 or 12 bit) and fewer artifacts at lower resolution, unless you've got a home IMAX or something.
Rips can achieve comparable quality with lower bitrate than used on the original disk. Blu-ray dates to 2006 and (typically) uses inefficient high bit-rate H.262 ("MPEG 2", which DVDs used), H.264 (AVC), or VC-1.
Rips can use high-efficiency H.265 ("HEVC"). Typical for a 1080p H.265 encoding is 9-15 GB. (Lower for animated films.)
UHD Blu-rays do use the more efficient H.265 already, but are much higher resolution as well. I'm not sure how prevalent they are.