Video File Size Calculator
Duration times bitrate, converted properly — the file size your export will produce, how long it'll take to upload, and YouTube's recommended bitrate bands for reference.
The formula, and the mistake it prevents
Video file size is bitrate × duration ÷ 8 — megabits per second times seconds, divided by eight to reach megabytes. The ÷8 is where casual estimates go wrong (bits and bytes differ by exactly that factor, and every 'why is my file 8× bigger than I thought' forum post is this arithmetic). This calculator does it properly and adds the number editors actually plan around: upload time at realistic upstream speeds, because a 40GB 4K export on a 10 Mbps connection is an nine-hour commitment someone should have mentioned before the deadline.
Choosing a bitrate that isn't a guess
Bitrate is the quality budget per second of video. YouTube's recommended upload settings are the practical reference — around 8–12 Mbps for 1080p, 16–24 for 1440p, 35–68 for 4K, with the top of each band for 60fps or HDR. Exporting far above these bands wastes disk and upload time (YouTube re-compresses everything to its own delivery formats anyway); exporting far below them hands YouTube a degraded master to re-compress further, which is where visible quality actually dies. Your editor's 'YouTube preset' typically lands inside these bands — this calculator lets you sanity-check what that preset will cost in gigabytes and hours before you hit export.
The workflow that saves render nights
Export a 60-second test clip at your chosen settings first: check its quality at full screen, multiply its size by your duration, and you know the full export's cost before committing the render. If upload time is the bottleneck, schedule uploads overnight rather than dropping bitrate — quality is permanent, upload delay is one night. And archive your masters at high bitrate even when the upload is done: re-compressing an already-compressed file for a future re-edit is the degradation you can't undo. Storage is cheap; a compressed-twice master is forever.
Frequently asked questions
How big is a 10 minute 1080p video?
At YouTube's recommended 8–12 Mbps for 1080p: roughly 600–900 MB (bitrate × 600 seconds ÷ 8). At 4K's 35–68 Mbps band the same 10 minutes runs 2.6–5.1 GB — resolution moves file size far more than duration does.
What bitrate should I export for YouTube?
YouTube's recommended upload settings: ~8–12 Mbps for 1080p SDR, 16–24 for 1440p, 35–68 for 4K, using the higher end for 60fps or HDR. Your editor's YouTube preset usually lands in-band; going far above wastes upload hours, far below sacrifices quality YouTube's re-compression makes worse.
Why is my exported file so much bigger than calculated?
Usually variable bitrate (VBR) exceeding its target on complex footage, a 'maximum quality' preset ignoring your bitrate setting, or reading megabits as megabytes (the ÷8). Check the export log's actual average bitrate — the formula is exact for the bitrate genuinely used.
Does YouTube compress my video after upload?
Always — every upload is re-encoded into YouTube's delivery formats at every resolution. That's why you upload the best master within recommended bands: you're choosing what YouTube's compression starts from, and compression of a clean source visibly beats compression of a compressed one.
How long does a YouTube upload take?
File size × 8 ÷ your upstream Mbps: a 1.5 GB video on a 10 Mbps upload takes ~20 minutes, on 50 Mbps ~4 minutes. This calculator shows both benchmarks; test your real upstream at speedtest sites — it's usually far below your download speed.
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