Estimate video, audio, and image file sizes before you record, encode, or export. Compare codecs and bitrates, then see how much storage you'll need for a whole batch of files.
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Unlike a simple unit converter, this file size calculator estimates how big a video, audio, or image file will actually be before you record, encode, or export it — starting from the settings that determine size in the real world: resolution, codec, bitrate, and duration for video and audio, or pixel dimensions and compression format for images. That makes it useful for planning camera storage, choosing an export preset, or budgeting cloud storage before a project even starts, rather than just converting KB to GB after the fact.
For video, the calculator starts from a typical H.264 bitrate for your chosen resolution (from 2.5 Mbps at 480p up to 100 Mbps at 8K), then adjusts it for your codec — H.265/HEVC runs at roughly 50% of the H.264 bitrate for the same visual quality, and AV1 runs at roughly 45% — and multiplies by your duration using size (MB) = bitrate (Mbps) ÷ 8 × duration (seconds). For audio, it multiplies your chosen bitrate (128-320 kbps, or ~1000 kbps for lossless FLAC) by duration the same way. For images, it first computes the uncompressed RAW size as width × height × bits-per-pixel ÷ 8, then divides by a compression ratio (roughly 2:1 for PNG, 10:1 for high-quality JPEG, 20:1 for standard JPEG) to estimate the real exported file size.
Storage and bandwidth are finite and often cost money, so knowing in advance that an hour of 4K H.264 footage needs roughly 15 GB — versus about 7.5 GB in H.265 — changes decisions about SD card size, recording codec, upload bandwidth, and cloud storage tier. The same logic applies to photographers choosing between RAW, PNG, and JPEG exports, or podcasters deciding between 128 kbps and lossless audio for distribution.
File size scales with pixel count and bitrate, not just resolution. Newer codecs (H.265, AV1) compress the same visual quality into a smaller bitrate than older H.264, roughly halving file size at equal quality — at the cost of more encoding time and less universal hardware support.
Higher bitrate means better fidelity and bigger files. Lossy formats like MP3 discard inaudible detail to shrink size; lossless formats like FLAC preserve every bit of the original recording at roughly 2-3× the file size of a high-bitrate MP3.
An uncompressed photo can be huge — a 12MP RGB image is roughly 36 MB raw. PNG compresses losslessly to about half that; JPEG throws away imperceptible detail for a 10-20× reduction, trading a small quality loss for a much smaller file.
Common questions about file size estimation
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