Video File Size Calculator

This calculator works out how much storage a video will take from its video bitrate, audio bitrate and running time. It also shows size per minute, how many hours fit on a 1 TB drive, and how long the file takes to upload at 20 Mbps. Videographers use it to plan memory cards and drives for a shoot, editors to estimate project storage, and streamers to see what a recording will weigh before uploading.

The result is exact for constant bitrate (CBR) recordings. Most cameras and encoders use variable bitrate (VBR), which spends more data on fast, detailed scenes and less on static ones, so real files land somewhat above or below the estimate. Container overhead adds a little on top.

Resolution and frame rate only matter through the bitrate they need; two 4K files can differ in size by ten times depending on codec and quality settings. Check your camera's manual or encoder settings for the actual bitrate. For transfer times on other connections, use the download time calculator.

This is the basic data-rate relationship used by every encoder. The calculator works in decimal megabytes and then reports gigabytes and drive capacity in binary units (1 GB = 1,024 MB), the way Windows shows them, so its GB figures are about 2.4% lower than a decimal conversion. The second line is the reverse calculation — a video bitrate calculator for hitting a target file size — explained below.

Use these as starting points when you do not know the exact bitrate. YouTube's recommended upload bitrates for standard frame rates are a good guide for delivery files; camera recording bitrates are usually higher because they keep more detail for editing.

When a platform or email limit caps the file size, run the formula backwards to find the highest bitrate you can use:

video bitrate (Mbps) = target size (MB) × 8 ÷ duration (s) − audio bitrate (Mbps)

To fit a 60-minute video into 4,000 MB with 128 kbps audio: 4,000 × 8 ÷ 3,600 = 8.89 Mbps in total, minus 0.128 for audio, leaves about 8.76 Mbps for video. Set the encoder slightly lower, around 8.5 Mbps, to leave room for container overhead and VBR peaks. A two-pass encode hits a target size more reliably than a single pass.

• Variable bitrate: the bitrate setting is an average or a maximum; scenes with motion, grain or foliage use more, static talking heads use less.
• Codec efficiency: H.265 (HEVC) and AV1 typically reach similar quality to H.264 at a noticeably lower bitrate, so switching codec changes the bitrate you need, not the formula.
• Multiple audio tracks: add each track's bitrate.
• Metadata and container overhead: usually small, around a percent or two.
• Drive formatting: a drive sold as 1 TB shows less usable space once formatted and reported in binary units; the data storage converter shows the difference.