Do the Math Before You Compress: Working the Four Calculators
"Compress this under 50MB" is the kind of request that punishes trial-and-error: one encode takes minutes, overshoot means another round. The four calculators turn the whole decision chain into arithmetic — you know the answer before you touch the encoder.
The core calculation: bitrate from target size
The entry point is the bitrate reverse calculator: total bitrate (kbps) ≈ target size (MB) × 8192 ÷ duration (seconds). The tool automates this — feed in the target size and duration, get the total bitrate to set, then split out the video bitrate by allocation (e.g. 128kbps reserved for audio). The result links straight into the compress-to-size tool, no manual copying.
Sanity-check the number against a bitrate reference table: if 720p only gets 500kbps, the target size is too tight for this footage — either raise the budget or drop the resolution. Forcing it means broken quality.
Three supporting calculations: size, ratio, timecode
Size forward (file size estimator): preview output size from current bitrate and duration — check platform limits before uploading. It runs the opposite direction from bitrate reverse, so the two validate each other. Aspect ratio: given a ratio (16:9, 9:16) and one side, get the other side and the simplified ratio — essential for cropping and canvas setup, avoiding that one-pixel-off embarrassment.
Timecode conversion: frames, seconds, and SMPTE timecode in three directions, with 29.97 drop-frame support. Subtitle sync and cut points think in seconds while editing software displays frames — hand-converting gets people into trouble on drop-frame time, every time.
Folding the calculators into your workflow
A recommended pre-processing ritual: get the requirement and duration, calculate bitrate (30 seconds) → sanity check against references (30 seconds) → set parameters and encode → verify output size with the estimator. Two minutes total, and the payoff is "right on the first encode" instead of a loop of re-encodes.
Know what calculators cannot do: they compute average bitrate while actual encoding floats with content complexity; CRF mode makes no size promise at all. Precise size needs the target-bitrate mode — two compression philosophies, and the calculators serve the latter.