How much iPhone storage do you need for dual camera video?
The honest answer depends less on which iPhone you own than on one habit: whether you delete a take from the app’s own library after you have saved it to Photos. Get that right and dual-camera video costs about what any other video does. Skip it, and the same hour of footage can end up sitting on your phone twice without you noticing.
The numbers below come from what DualCam actually writes to disk, not a guess, so you can do the arithmetic for your own shooting habits instead of trusting a rule of thumb.
The one number that matters: about 4 GB an hour
DualCam encodes its composited video at roughly 10 Mbps, which works out to about 75 MB a minute — a little over 4 GB for an hour of continuous recording. That number does not change if you switch between the app’s two capture settings, 720p and 1080p, because capture resolution only changes how much detail is drawn into the frame, not the size of the canvas being written. A 720p hour and a 1080p hour cost the same amount of storage; the 1080p one just looks sharper for the space it takes.
That also means running two cameras at once is not the multiplier it sounds like. The output is one composited file, not two recordings added together, so a dual-camera hour costs about the same as an hour of ordinary single-camera 1080p video on the same phone — not twice it.
The real cost is double, until you delete one copy
A recording lands in DualCam’s own library the moment you stop filming. Tapping Save copies it into Photos — it does not move it, so the original stays exactly where it was. Until you go back into the app and delete that original, the same footage sits on your phone twice: once in the app’s library, once in Photos.
That turns 4 GB an hour into roughly 8 GB an hour for anything you have saved and not cleaned up. A handful of short clips duplicated this way barely registers, but an hour-long walking vlog or study session, saved once and forgotten about in the app, is a multi-gigabyte copy sitting somewhere you stopped checking. Deleting the app’s copy after confirming the save is the one step that actually gets that space back — deleting from Photos alone does nothing to it, since the two libraries were never linked.
The floor at the bottom you cannot use
DualCam needs at least 200 MB genuinely free to start a recording, and it stops an in-progress take once free space drops under 100 MB, rather than let it fail badly. That is not a large amount next to a modern iPhone’s capacity, but it means the very last sliver of storage shown in Settings is not usable recording time — plan around the space you can actually spend, not the number at the top of the storage screen.
This is also why “how much is free” matters more than “how much does my iPhone have.” A large-capacity phone that is nearly full behaves, for filming purposes, like a much smaller phone that is empty.
Sizing it to how you actually shoot
None of this needs a spreadsheet — a rough sense of your own habits is enough. Someone who records the occasional ten- or thirty-second reaction clip will not notice dual-camera video against everything else on a phone; a handful of those a week is a rounding error even on a smaller-capacity iPhone. Someone shooting hour-long vlogs, tutorials or study sessions on a regular basis is the person who should actually run the math above, because that is where 4 GB an hour, potentially doubled, adds up over a month.
The habit that matters more than any storage tier: review a take in DualCam’s library, save the ones worth keeping, and delete the app’s copy once you have confirmed it landed safely in Photos. That single step is what keeps a storage-hungry habit from turning into a phone that is mysteriously always full.
Common follow-up questions
Does recording at 720p instead of 1080p use noticeably less storage?
No. DualCam’s canvas size is fixed regardless of capture resolution, so 720p and 1080p both cost roughly 75 MB a minute — the difference is how much detail is in that file, not how big it is.
If I delete a saved video from Photos, does that free up the space in the app too?
No. DualCam’s library and Photos are two separate libraries that were never linked, so a deletion in one is invisible to the other. Getting the space back means deleting the take inside the app as well.
Is there a minimum amount of free space I need before I can even start recording?
Yes — DualCam needs at least 200 MB genuinely free to start a take, and it will stop an in-progress recording if free space drops under 100 MB, so the very last sliver of a full iPhone is not usable recording time.
Want to just do this?
DualCam records the iPhone front and back cameras at the same time and writes one finished MP4 while you shoot. Free, no account, no ads, nothing leaves the phone.