Video Length Calculator: Total Runtime, File Size, and Compression Estimates
Whether you're planning a YouTube playlist, estimating a backup's total time, or budgeting storage for a project, knowing how to add up video durations is surprisingly handy. This calculator handles HH:MM:SS arithmetic and rough size estimates.
Adding video lengths in your head is awkward — minutes wrap at 60, hours at 24, and seconds at 60. A 47-minute video plus a 38-minute video is 1h 25m, not 0h 85m. The calculator does this conversion automatically and handles any number of clips.
Beyond just summing, it also estimates file size based on typical bitrates. A 1-hour 1080p video is roughly 1–2 GB at standard YouTube bitrates; the same video at 4K might be 5–10 GB. These figures are useful for planning storage and uploads.
Approximate file size per minute by quality
Estimates only — actual size depends on the codec, scene complexity, and encoder settings.
| Resolution | Bitrate (avg) | Per minute | Per hour |
|---|---|---|---|
| 480p | 1 Mbps | 7.5 MB | 450 MB |
| 720p | 2.5 Mbps | 19 MB | 1.1 GB |
| 1080p | 5 Mbps | 37 MB | 2.2 GB |
| 1440p | 10 Mbps | 75 MB | 4.5 GB |
| 4K | 20 Mbps | 150 MB | 9 GB |
| 4K HDR | 35 Mbps | 260 MB | 16 GB |
Common use cases
- •Planning a YouTube watching session — sum up the lengths of videos in a playlist.
- •Estimating storage for a recording project (interviews, podcast video, gameplay footage).
- •Calculating total course length for online education or training.
- •Budgeting upload time on a slow connection — a 4 GB file over a 10 Mbps connection takes about an hour.
Extended FAQ
Does this account for compression?
Yes — the size estimates assume standard H.264 compression at typical bitrates. H.265/HEVC and AV1 produce smaller files at the same quality; raw or uncompressed video is 10× larger or more.
Why is my actual file size different?
Bitrate is an average. Action-heavy or detailed footage encodes larger; static talking-head videos encode smaller. Constant-quality (CRF) encoding produces variable-size output.
Are my entries saved?
No — runs entirely in your browser.