Video File Size Calculator - Bitrate, Duration & Storage for 1080p and 4K
Video File Size Calculator
File size from bitrate and duration, or the bitrate that fits
Three Ways Round
Size from bitrate and length, bitrate for a target size, or length that fits.
Typical Presets
Start from common upload bitrates for 720p, 1080p, 1440p and 4K.
GB and GiB
See decimal gigabytes as drives are sold and binary gibibytes as many operating systems report.
Private
Calculated in your browser.
How Big Is a Video?
File size is simply bitrate × duration ÷ 8, because bitrates are in bits and sizes in bytes. Add the audio bitrate to the video bitrate first. Example: 10 minutes of 1080p at 8 Mbps with 128 kbps audio is (8.128 Mbps × 600 s) / 8 = 609.6 MB, about 0.61 GB.
Real files vary because most encoders use a variable bitrate, and containers such as MP4 add a little overhead. Codec matters too: H.265/HEVC and AV1 reach the same quality as H.264 at roughly 30-50% lower bitrate. Storage makers count 1 GB as 1,000,000,000 bytes, while Windows shows GiB (1,073,741,824 bytes), so a "64 GB" card appears as about 59.6 GB.
Key Takeaways
- Bits vs bytes: Divide bitrate × time by 8 to get bytes.
- Leave headroom: Allow a few percent for container overhead and bitrate peaks.
- Codec choice: Newer codecs need less bitrate for the same quality.