How the numbers work
Estimated payload bytes = duration in seconds × (average video Mbps × 1,000,000 + audio tracks × audio kbps × 1,000) ÷ 8. The container allowance multiplies payload bytes by (1 + allowance ÷ 100). Variation changes video payload alone by ± the selected percentage, producing a low/high planning range. It is not a confidence interval.
For “fit a limit,” the budget is limit × (1 − safety margin ÷ 100). The bitrate and maximum-duration solvers use the high side of the range, then round the solved target down. If the audio payload already exhausts the budget, the bitrate solver reports an error instead of inventing a negative bitrate.
Upload time = file bytes × 8 ÷ (upload Mbps × 1,000,000 × effective throughput fraction). Required speed reverses that equation using the high file-size estimate. The ideal-wire figure assumes 100% throughput; neither number includes service-side processing after upload.
Units and bitrate labels
MB and GB here are decimal bytes (1,000,000 and 1,000,000,000); MiB and GiB are binary bytes (1,048,576 and 1,073,741,824). A byte is eight bits. Mbps and kbps are decimal bits per second, not megabytes/kilobytes per second. An encoder’s peak or maximum video bitrate is not its average rate. See NIST’s byte-prefix definitions.
Export limits
Variable-bitrate encoders change actual output with content complexity, so the chosen range and container allowance are planning inputs, not promised codec or platform behavior. Measure one representative encode before relying on a tight cap. Codec choice, quality mode, subtitles, extra streams, metadata, mux padding, and transcoding or platform-side handling can change bytes. Check the destination’s current upload rules yourself. See Adobe’s export-setting guidance on target and variable bitrate.
Frequently asked questions
Why did the export exceed the predicted size?
The video rate entered may not be the final average, the audio tracks may differ, or the overhead allowance may be too small. The solver is planning arithmetic, not an encoder. Use a larger variation/allowance or a lower export target and verify a test export.
Does this guarantee my video fits a platform’s limit?
No. The tool accepts your current limit and shows an assumption-dependent range and planning budget. Platform limits vary by product, account, and time; final output must be checked after encoding.
Does choosing a file upload it?
No. The browser reads only the selected file’s size property. Its contents are not decoded, transmitted, or retained by this tool.
Does upload time include cloud processing?
No. It estimates transfer over your measured upload link at a chosen effective-throughput percentage. Retries, concurrent traffic, server throttling, and processing after transfer may extend elapsed time.