Video File Size Calculator
Estimate how big a video file will be before you record or export. Enter the runtime in seconds, minutes, or hours and pick a resolution preset (with stated YouTube-recommended H.264 bitrates from 480p to 4K) — or type any custom bitrate in Mbps.
Example: with Runtime 10 · Runtime unit minutes · Resolution preset (H.264 bitrate) 1080p Full HD — 8 Mbps · Custom bitrate (Mbps) 8 → Estimated file size: 600 MB (0.60 GB).
- Per hour at this bitrate3.60 GB (3,600 MB) per hour
- Bitrate used8 Mbps (1080p — YouTube-recommended H.264, SDR, 24-30 fps)
Computed by the calculator below using its default values. Change any input to see your own numbers.
File size = bitrate × seconds ÷ 8 (bits to bytes). Ten minutes of 1080p at YouTube's recommended 8 Mbps is 600 MB; the same ten minutes in 4K at 45 Mbps is 3.4 GB.
Bitrate times runtime — that is the whole formula
Video size barely depends on resolution directly; it depends on the bitrate the encoder writes. Multiply megabits per second by seconds, divide by 8 to turn bits into bytes, and you have the file size. Resolution enters only because higher resolutions need higher bitrates to look good — which is what the presets encode, using YouTube's recommended H.264 upload settings (2.5 Mbps for 480p up to 45 Mbps for 4K, SDR at standard frame rates).
The same 10-minute clip can therefore be 60 MB or 6 GB. Streaming services push bitrates down with efficient codecs (HEVC and AV1 hit similar quality at 30-50% less), while cameras push them up — a phone recording 4K often writes 50-100 Mbps, several times the upload preset.
How it’s calculated
File size (MB) = bitrate (Mbps) × duration (seconds) ÷ 8, using decimal units (1 GB = 1,000 MB). Presets are YouTube's recommended H.264 upload bitrates for SDR at 24-30 fps: 2.5 (480p), 5 (720p), 8 (1080p), 16 (1440p), and 45 Mbps for 4K (from the published 35-45 Mbps guidance). Audio adds about 1-3 MB per minute (128-384 kbps) on top.
Real encoders vary bitrate with motion and complexity (VBR), so exports commonly land 10-20% off the estimate; 60 fps or HDR needs roughly 1.5× these bitrates.
Ten minutes of H.264 video by resolution
| Resolution | Bitrate | File size |
|---|---|---|
| 480p SD | 2.5 Mbps | 188 MB |
| 720p HD | 5 Mbps | 375 MB |
| 1080p Full HD | 8 Mbps | 600 MB |
| 1440p QHD | 16 Mbps | 1.20 GB |
| 4K UHD | 45 Mbps | 3.38 GB |
Size = bitrate × 600 s ÷ 8, decimal MB/GB; bitrates are YouTube's recommended H.264 upload settings (SDR, standard frame rate).
Common mistakes
- Skipping the ÷ 8: bitrates are megaBITS per second — an 8 Mbps stream writes 1 megaBYTE per second, not 8.
- Using upload presets to predict camera recordings — phones and cameras record at 50-100+ Mbps, many times these rates.
- Ignoring audio on long files: a 2-hour recording carries 15-45 minutes' worth of video bits in audio alone at high audio bitrates.
- Comparing decimal GB to what Windows shows — a 20.25 GB (decimal) file reads as about 18.9 GiB in Explorer.
Frequently asked questions
What is the video file size formula?
Size in MB = bitrate in Mbps × duration in seconds ÷ 8. The ÷ 8 converts bits to bytes. One hour at 8 Mbps: 8 × 3,600 ÷ 8 = 3,600 MB = 3.6 GB.
How big is one hour of 1080p video?
At YouTube's recommended 8 Mbps upload bitrate, about 3.6 GB. A streaming-quality 5 Mbps copy is 2.25 GB, and a camera original at 50 Mbps is 22.5 GB.
Why are my phone videos so much bigger than this?
Phones record at high bitrates to preserve quality for editing — often 50-100 Mbps in 4K. Enter your phone's actual bitrate as a custom value; iPhones and Androids list it under camera settings.
Is a megabit the same as a megabyte?
No — 8 megabits make 1 megabyte. Network and video bitrates use bits (Mbps); file sizes use bytes (MB). Mixing them up is an 8× error in either direction.