SD Card Capacity Calculator

Pick your card and your recording settings — find out how much video time fits, the data rate, and the minimum card class you need to avoid dropped frames.

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Your shoot

Card capacity
Resolution
Frame rate (fps)
Recording time that fits
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0MB/s data rate
—minimum class required
0GB / minute
0total minutes
Time per card
Quick scenarios
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0 MB/s · —

How SD card capacity is calculated

The time a card holds is its usable capacity divided by how fast the camera writes data:

Time = usable capacity (MB)data rate (MB/s)

The usable capacity starts from the labelled size in decimal GB, the way cards are sold (128 GB = 128 billion bytes), minus a 2% margin; the exFAT file system itself takes under 1%. If your computer shows "119 GB", that is the same space counted in GiB. The data rate (MB/s) is set by your resolution, frame rate and codec — the higher they are, the more megabytes per second and the less time fits. Divide one by the other and you get the duration. We also tell you the minimum card class you need: if your card is slower than that data rate, recording stops or drops frames.

Example: how much 4K video fits on 128 GB

You have a 128 GB card and shoot 4K UHD at 30 fps in H.265:

  • 128 GB × 0.98 ≈ 125.4 GB usable.
  • 4K30 in H.265 = 100 Mbps = 12.5 MB/s data rate.
  • 125,440 MB ÷ 12.5 MB/s ≈ 10,035 s ≈ 2 h 47 min of recording.
  • Minimum class: a V30 card is enough for that data rate.

Switch the codec to ProRes 422 HQ (110 MB/s) and the same card drops to about 19 minutes — and that data rate is beyond SD-card limits: you'd need CFexpress Type A or an external SSD.

SD card capacity FAQ

How much video fits on a 128 GB card?
It depends on resolution, frame rate and codec. At 4K 30 fps in H.265 (about 12.5 MB/s) you get about 2 h 47 min; in H.264 (25 MB/s), half that. In ProRes 422 HQ it is about 19 minutes. Enter your settings and the calculator gives the time for your case.
Why does my computer say my 128 GB card has 119 GB?
No space is missing: it is the same capacity in a different unit. The card holds 128 billion bytes (decimal GB, the way cards are sold), while Windows counts in GiB (1 GiB = 1.074 GB), so it shows 119.2. The exFAT file system takes under 1%. The calculator counts 98% of the labelled capacity as usable, to leave a small margin.
What card class do I need so recording does not drop?
The minimum class depends on the data rate (MB/s), not the card size. The calculator shows the exact class — V30, V60, V90 or, for high data rates, CFexpress / SSD.
Does it also work for CFexpress and SSDs?
Yes. When the data rate exceeds what an SD card can sustain, the tool recommends CFexpress Type A, CFexpress Type B or a high-performance SSD.
Are the times exact?
The division is exact; the starting bitrate is a typical estimate per codec, while every camera uses its own and it varies with the scene. If you know your camera’s real bitrate, check it with the bitrate calculator, and leave 10–15% headroom.