Video File Size Calculator

Video File Size Calculator is a single-page tool for the common video editing and conversion task it is named after. Calculate the file size of a video given its video bitrate, audio bitrate, and duration. Get the size in MB, GB, and the total bytes per second. Pure math — runs instantly in your browser. The interface keeps the input on one side, the configurable options in the middle, and the result on the other side. Most jobs start and finish without any scrolling.

Behind the controls you see, FFmpeg compiled to WebAssembly is doing the actual video editing and conversion. MP4, WebM, MOV, MKV, AVI, FLV, and OGV are first-class formats and the engine produces a deterministic output for any given input + options combination — useful when you need to re-run a job and expect identical results.

Video File Size Calculator is a static page plus a client-side engine. The browser does the work; there is no separate backend in the loop for the actual processing. That architecture is why the tool starts immediately, why it does not depend on the load on a remote service, and why running multiple jobs in a row does not slow it down.

The heaviest users of Video File Size Calculator tend to be students submitting video assignments, product teams shipping release demos and social-media managers cutting reels. Each group brings slightly different expectations to the tool, but the same single-page architecture serves every one of them with the same response time.

Video File Size Calculator works well as a bookmarked utility you reach for when you need it. The first visit shows you what the tool does; the second is when you realise it is a low-friction option for the task and worth keeping in your tab list.

The hard constraints are easy to remember. Maximum input: 500 MB. Multiple files per run: no — one input at a time, by design, to keep results predictable. The same controls apply on every run.

Workflow tip: Video File Size Calculator pairs well with Video Bitrate Calculator and Video Size Estimator. Other adjacent tools you may find useful are Video Duration Calculator and Video Bitrate Reducer. Because every tool is a separate page, you can mix and match the steps that match your job. Bookmark the ones you reach for the most.

Some notes on the design of Video File Size Calculator. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.

Video File Size Calculator returns the result as `{name}-edited.{ext}`. If you are running multiple jobs, the output names will not collide as long as the input names differ. You can re-run with different settings as many times as you like; each run produces a fresh file with no caching trickery in between.

Some background on the design choices behind Video File Size Calculator: every option you see on the page is there because a real workflow needs it, and every option that is not shown has been deliberately omitted to keep the common case fast. The bias is toward minimal-but-complete.

If you also use a command-line tool for video file size calculator, Video File Size Calculator is a convenient alternative for the times you are on a different machine or helping someone who is not comfortable in a terminal. The output is a standard file in the format documented above.

Useful patterns when working with Video File Size Calculator: keep the input file open in another tab so you can compare against the result; give the output file a descriptive name when saving so you can find it later (the default name is sensible but generic); and treat each run as independent — the tool has no concept of "history", which means you cannot accidentally pollute one job with leftovers from another.

If the result is not what you expected, the most common causes are easy to check. Confirm the input is under the 500 MB ceiling — files just above the cap fail silently because the engine refuses to allocate the buffer. Confirm the input is one of the supported formats. And if the page itself feels slow, try closing other heavy tabs to free up memory; the engine runs in your browser, so it competes for the same resources as everything else open.

Video File Size Calculator is one of many single-purpose tools in the catalog. Each is built around the same single-page model. Use this one, close the tab, and come back the next time you need the same job done. None of the tools require prior knowledge of the others — each page is self-contained.