💾 Video File Size Estimator
Enter your video's resolution/quality and duration to estimate the resulting file size, based on commonly used bitrates for that resolution.
Bitrate times seconds, divided by eight
Bitrate is measured in bits, file size in bytes, so the division by eight is the whole conversion:
size MB = bitrate Mbps × duration seconds ÷ 8
size GB = size MB ÷ 1024Ten minutes at the 1080p preset of 8 Mbps is 8 × 600 ÷ 8 = 600 MB. The same ten minutes at the 4K preset of 40 Mbps is 3,000 MB, shown as 2.93 GB. Under 1 GB the result is shown in whole megabytes, above it to two decimals.
Run it backwards to hit a size limit: bitrate = size MB × 8 ÷ seconds. To fit a 20-minute video into 500 MB you need 500 × 8 ÷ 1200, or about 3.3 Mbps.
Why your export will not match exactly
- The four bitrates are hard-coded presets, not a reading from your encoder. With no custom-bitrate box, pick the nearest preset and treat the answer as approximate.
- Codec changes it more than resolution does. HEVC or AV1 hold similar quality at roughly half the bitrate of H.264, which halves the file.
- Frame rate scales with it. 60 fps needs about 1.5 times the bitrate of 30 fps.
- Variable bitrate averages out. A static talking head lands under the target; fast motion and grain overshoot it.
Frequently asked questions
How big is a 10-minute 1080p video?
Roughly 600 MB at 8 Mbps. A phone recording at 20 Mbps puts the same ten minutes near 1.5 GB, and an HEVC export at 4 Mbps around 300 MB - the bitrate matters far more than the resolution label.
How do I calculate video file size from bitrate?
Multiply the bitrate in megabits per second by the length in seconds, then divide by eight to get megabytes. A 2-minute clip at 16 Mbps is 16 × 120 ÷ 8 = 240 MB.
Does this include the audio track?
Only in the sense that the presets are whole-file averages. Audio adds 128 to 320 kbps, another 10 to 24 MB on a ten-minute video - small beside the video, but not nothing.