Video File Size Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/6/2026
A video file's size is estimated with size (MB) = bitrate (Mbit/s) × duration (min) × 60 ÷ 8. For a 1080p video at 8 Mbit/s for 10 minutes, the estimated size is about 600 MB, or 0.6 GB.
Explanation
A video's bitrate indicates how much data is encoded each second, usually expressed in megabits per second (Mbit/s). The total file size follows directly by multiplying this rate by the video's total duration, then converting megabits to megabytes (1 byte = 8 bits, hence the division by 8 — a frequent point of confusion, since the lowercase "b" denotes a bit and the uppercase "B" a byte). This calculator uses the decimal convention (1 GB = 1000 MB), the one used by file systems and online storage services, rather than the binary convention (1024) sometimes used internally by certain operating systems — the gap between the two conventions is detailed in our data conversion calculator. The actual bitrate depends heavily on the video codec used (H.264, H.265/HEVC, AV1…): for the same perceived quality, a newer codec like H.265 typically needs roughly half the bitrate of H.264, so this calculator only accounts for the rate you enter, not the underlying codec. To estimate the time needed to read a text rather than a video's file size, see our reading time calculator.
Example: a 1080p video at 8 Mbit/s for 10 minutes
Inputs
Bitrate: 8 Mbit/s. Duration: 10 minutes.
Calculation
Size = 8 × 10 × 60 ÷ 8 = 4800 ÷ 8 = 600 MB. In gigabytes: 600 ÷ 1000 = 0.6 GB.
Result
This video weighs about 600 MB, or 0.6 GB.
Frequently asked questions
Why is my file's actual size a bit different from this estimate?
This calculation assumes a constant bitrate (CBR) throughout the video. But most modern videos use a variable bitrate (VBR), which allocates more data to complex scenes (fast motion, fine detail) and less to simple ones (a static shot, flat colors): the real average bitrate can therefore drift slightly from the target setting. On top of that, the audio track and container metadata add weight not accounted for here.
What bitrate should I choose for a given quality?
There's no universal value: the bitrate needed for a given perceived quality depends on resolution, frame rate, scene complexity, and the codec used. As a very rough guideline, streaming platforms often recommend about 5 to 8 Mbit/s for 1080p and 25 to 45 Mbit/s for 4K in H.264 — a newer codec like H.265 allows noticeably lower values for equivalent quality.
Does this calculator also work for estimating an audio file size?
Yes, the principle is identical: an audio file encoded at 320 kbit/s (i.e. 0.32 Mbit/s) for 4 minutes weighs about 0.32 × 4 × 60 ÷ 8 ≈ 9.6 MB. Just convert the audio bitrate to megabits per second before using it in this calculator.