How many GB is a digitized VHS tape?
Captured as high-quality lossy video at 25 Mbps, a 2-hour VHS tape becomes about 22.5 decimal GB; a common 10 Mbps H.264 capture is about 9 GB, and lossless workflows run far larger. Storage scales linearly with both bitrate and tape length.
The storage formula
Bitrate is data per second. Multiply the chosen megabits per second by the number of seconds, then divide by eight to convert bits to bytes. The page reports decimal GB, which matches how storage manufacturers usually label drive capacity.
decimal GB = Mbps × duration in seconds ÷ 8,000
At 8 Mbps, one hour contains 28,800 megabits. Dividing by eight produces 3,600 megabytes, or 3.6 decimal GB. Twenty recorded hours at the same constant rate produce 72 GB of video payload. Three independent copies require 216 GB in total.
Why the actual file will differ
The exact result applies to the bitrate entered. Real-world files also contain audio, container metadata, indexes, and sometimes subtitles or timecode. A variable-bitrate encoder changes its data rate according to the picture, so its displayed average may only be known after encoding. Analog tape noise can also make compression less predictable.
Resolution is not included in this equation because bitrate alone determines the amount of compressed data per second. Two files can share a resolution and have very different bitrates, or share a bitrate while using different codecs and producing different visual results.
Capture time is not download time
Analog tape has to be played. A two-hour VHS recording generally needs two hours just for capture. Setup, a short playback test, encoding, quality control, file naming, and copying require additional time. Public-library workflows commonly tell users to budget more than the recorded duration. The calculator starts at 1.5 work hours per recorded hour, but exposes that multiplier because workflows differ.
Choose the workflow before the bitrate
This tool deliberately does not label one preset “archival.” A preservation master, an editing intermediate, and a convenient family access copy have different goals. Select playback hardware, capture device, signal path, codec, interlacing treatment, and quality-control process first. Then enter the data rate produced by that workflow to plan capacity.
If the tape is mouldy, brittle, shedding, creased, or irreplaceable, do not treat a storage estimate as permission to play it. Condition assessment and equipment maintenance are outside this calculator’s scope.
Sources and calculation status
The storage equation is pure unit conversion. The 1.5× work multiplier is an editable planning assumption consistent with several public-library Memory Lab guides; it is not part of the storage formula. The Canadian Conservation Institute provides a deeper guide to VHS condition, equipment, capture choices, masters, access files, and backup copies.
Primary references: DC Public Library Memory Lab transfer guides; Canadian Conservation Institute Technical Bulletin 31.
Frequently asked questions
Why does my capture software show a different size?
Check whether it reports GB or GiB, whether the bitrate is variable, and whether the displayed rate includes audio. Container overhead and rounded display values also create small differences.
Can I enter a lossless codec’s bitrate?
Yes. Use the measured average bitrate from a representative test capture. Lossless bitrate varies greatly with signal and codec, so a measured rate is more useful than a generic preset.
Should I keep both a master and a smaller copy?
Many workflows retain a high-quality master and create smaller access copies for everyday viewing. If you do, calculate them separately and add the totals; do not assume the smaller copy replaces the master.
Does the tool work for PAL and NTSC?
The bitrate equation works for either. The correct frame rate, frame dimensions, color system, and capture workflow still depend on the original format and equipment.
Have several media types? Combine this result with photos, film, and audio in the media archive planner.