Find out how long you can record on a 64 GB, 128 GB or 1 TB card before it fills up, or how much storage a shoot of a given length needs. Pick a phone, action camera, camera, ProRes, dash cam or security camera profile, or type your own bitrate.
Last updated:
What do you want to know?
Recording format
Typical total bitrates (video + audio). Check your device's settings or a sample clip for exact figures.
Mbps
kbps
AAC is often 128–320 kbps; 48 kHz 16-bit stereo PCM is 1,536 kbps.
Storage
h
min
%
File system, thumbnails and a safety margin. 2–5% is typical.
Use 1 for a single card. Use more for NVRs or multi-cam shoots sharing one drive.
Enter your values to see the result.
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How to use the Video Recording Time Calculator
Choose a mode: Recording time on a card, or Storage for a recording.
Pick your camera or phone profile, or choose Custom bitrate, or Estimate from resolution & fps.
Enter the card capacity (time mode) or the recording length (storage mode).
Adjust reserved space and number of cameras if several cameras record to the same drive.
Press Calculate (it also updates live) and read the recording time, storage, card speed and the card-size table.
How video recording time is calculated
A camera writes data at a fairly steady rate, its bitrate. Once you know it, recording time is simple division:
Recording time (s) = usable capacity (bytes) × 8 ÷ bitrate (bits per second) Storage needed (bytes) = bitrate (bits per second) × recording time (s) ÷ 8
Example: a 256 GB card with 3% kept free has 248.32 GB usable = 248,320,000,000 bytes. At 150 Mbps (150,000,000 bits/s, or 18.75 MB/s) it holds 248,320,000,000 ÷ 18,750,000 ≈ 13,244 seconds, about 3 hours 40 minutes. With two cameras writing to the same drive, divide by two.
Useful shortcuts: 1 Mbps ≈ 7.5 MB per minute ≈ 0.45 GB per hour. So 100 Mbps is about 45 GB per hour, and a phone recording 170 MB per minute runs at about 22.7 Mbps.
Recording time reference (decimal GB, no reserved space)
Bitrate
Typical use
GB per hour
64 GB
128 GB
256 GB
1 TB
4 Mbps
Security camera 1080p
1.8
35 h 33 min
71 h 6 min
142 h 13 min
555 h 33 min
12 Mbps
Dash cam 1080p
5.4
11 h 51 min
23 h 42 min
47 h 24 min
185 h 11 min
22.7 Mbps
Phone 4K 30 fps HEVC
10.2
6 h 16 min
12 h 32 min
25 h 3 min
97 h 53 min
50 Mbps
Camera 1080p long-GOP
22.5
2 h 50 min
5 h 41 min
11 h 22 min
44 h 26 min
100 Mbps
Action cam / camera 4K
45
1 h 25 min
2 h 50 min
5 h 41 min
22 h 13 min
400 Mbps
4K All-Intra
180
21 min
42 min
1 h 25 min
5 h 33 min
707 Mbps
ProRes 422 HQ, 4K UHD 30 fps
318
12 min
24 min
48 min
3 h 8 min
Tips for choosing a card or drive
Check the speed class, not only the size. Divide the bitrate by 8 to get MB/s; V30 cards guarantee 30 MB/s (240 Mbps) of sustained writing, V60 60 MB/s and V90 90 MB/s.
Measure your real bitrate. Record one minute, note the file size in MB and multiply by 8 ÷ 60 to get Mbps. Variable bitrate modes can land well below the advertised maximum.
Leave headroom. Cameras store thumbnails and index files, and some stop recording before the card is completely full; keeping 5–10% free also protects against a surprise long take.
For security systems, multiply by the number of cameras and the hours recorded per day; motion-only recording can stretch retention far beyond continuous recording.
Back up and reformat the card in the camera after each shoot; fragmented cards can cause dropped frames at high bitrates.
Frequently asked questions
How many hours of video fit on a 128 GB SD card?
It depends on the bitrate. Recording time (seconds) = usable bytes × 8 ÷ bitrate in bits per second. At about 23 Mbps (phone 4K 30 fps in HEVC) a 128 GB card holds roughly 12 hours; at 100 Mbps (action camera or camera 4K) about 2 hours 50 minutes; at 400 Mbps All-Intra about 42 minutes, before subtracting a few percent for the file system.
How do I calculate video recording time from bitrate?
Convert the capacity to bits and divide by the bitrate. A 64 GB card is 64,000,000,000 bytes × 8 = 512,000,000,000 bits. At 50 Mbps (50,000,000 bits per second) that is 10,240 seconds, or 2 hours 50 minutes. Add the audio bitrate to the video bitrate if your figure is video only.
Why does my 128 GB card show only about 119 GB?
Card makers use decimal gigabytes (1 GB = 1,000,000,000 bytes), while Windows and many cameras count in binary units (1 GiB = 1,073,741,824 bytes) but still label them GB. 128,000,000,000 bytes ÷ 1,073,741,824 ≈ 119.2 GiB. No space is missing; the file system and camera folders then use a little more.
What SD card speed class do I need for 4K video?
The card must sustain the camera's write rate: bitrate in Mbps ÷ 8 = MB/s. 100 Mbps needs 12.5 MB/s, so a V30 (30 MB/s) card is the usual choice for 4K long-GOP recording. 200–400 Mbps All-Intra needs 25–50 MB/s, so V60 or V90, and very high ProRes or RAW rates usually need CFexpress or an SSD.
Why does my camera split long recordings into 4 GB files?
Cards of 32 GB and smaller are formatted with FAT32, which cannot store a file larger than 4 GB, and many cameras keep the 4 GB chunk size on larger exFAT cards for compatibility. The recording continues seamlessly into the next file; the calculator shows how often a new file starts at your bitrate.
Does resolution or frame rate change the recording time?
Only through the bitrate. Storage used = bitrate × time, so a 4K mode recorded at the same bitrate as a 1080p mode fills a card at exactly the same speed. In practice higher resolutions, higher frame rates and less efficient codecs (H.264 vs H.265) use higher bitrates, which is why they fit fewer minutes.
How accurate are the camera and phone profiles?
They are typical published or commonly measured average bitrates, rounded. Real files vary with the scene, variable bitrate encoding, audio format and firmware. For an exact figure, record a one-minute test clip, check its size in MB and convert: MB per minute × 8 ÷ 60 = Mbps, then use the Custom bitrate option.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.