File Size Converter — All Units
Convert file sizes between bytes, KB, MB, GB, TB, and PB using binary (1024-based) units.
How it works
- 1Type or paste in the file size (e.g. "1.5 gb", "1024 kb", "5000000") field
- 2Conversion happens instantly in your browser
- 3Copy the result with one click
What to do next
About File Size Converter
File Size Converter handles a focused step in the modern developer utility workflow. Convert file sizes between bytes, KB, MB, GB, TB, and PB using binary (1024-based) units. The page loads with the upload area, controls and result panel all visible at once, so the path from "I have a file" to "I have the result" is one screen long.
File Size Converter sees the most use from data analysts wrangling JSON and backend developers inspecting requests, but the design is intentionally generic enough that you do not need a specialist background to get a good result. The defaults aim at the most common case so a first-time user can get the right output without changing any settings.
Most people land on File Size Converter via a search at the moment they actually need the tool. That shapes the design: the page is a single screen with the input on one side, the controls in the middle, and the result on the other, so a first-time visitor can complete the job without reading documentation.
File Size Converter runs on standard browser APIs — an open-source, well-audited engine that performs the developer utility natively in the browser. It accepts the formats listed in the upload area and produces output that opens in any standard developer viewer. Per-run input is capped at 0 MB.
The architecture is local-first by design. Once the page is loaded, you can disconnect from the network and the tool still completes the job. The processing stack — standard browser APIs and the small UI shell wrapping it — ships with the page itself, so the tool keeps working in offline conditions, on a captive-portal Wi-Fi, or behind a corporate proxy that limits what the tab can reach.
Once you have used File Size Converter, the natural next steps depend on what you are doing with the result. Common follow-ups include Byte ↔ Bit Converter, Bundle Size Estimator, and Web Performance Calculator. These are surfaced on the page so you do not have to hunt the catalog manually.
On limits: 0 MB per file is the ceiling. Output formats and quality settings are listed in the controls panel above, and they apply to every run.
The transformation in File Size Converter is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
Output handling is intentionally boring: File Size Converter produces a single output file and triggers your browser's standard "save" behaviour. If you have a default download folder configured, that is where it will land. There is no Favtoo-side history of jobs you have run.
File Size Converter is one example of a broader pattern: utility software increasingly works as single-page, client-side experiences. Every page in the catalog is shaped that way, which keeps each tool fast to load and easy to recommend in a single link.
File Size Converter runs as a regular web page, so there is no install step or permission grant before the first run. The page can be audited by viewing the source or by watching the developer-tools Network tab while a job runs.
Tips from users who reach for File Size Converter regularly: process one input first to confirm the settings produce what you expect before committing to a batch; treat the page as the working surface and avoid leaving large jobs running in a backgrounded tab where the browser may throttle JavaScript; and if a particular file fails, check whether the source is intact by opening it in its native viewer — most "tool errors" are actually input errors.
When something goes wrong, the cause is usually one of three things: a malformed input, a browser that is out of memory, or a corporate proxy that is interfering with the page's static assets. The first two are easy to diagnose; the third typically requires asking your IT team to allow standard browser APIs to load.
If File Size Converter solved your problem, sharing the page link with someone who has the same problem is the most useful thing you can do. The catalog grows mostly through word of mouth; visitors arriving through a recommendation tend to be the ones the tool serves best.
How it works
- 1Open File Size Converter in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Select the developer file you want to process — drag-and-drop and the file picker both work.
- 3Pick any non-default settings you need. Most users leave the defaults alone for the first run and only revisit if the result needs tuning.
- 4Trigger processing. standard browser APIs reads your input, applies the transformation, and writes the result back into the page.
- 5Grab the output as soon as the run completes. You can also copy the result instead of downloading if the next tool in your workflow accepts pasted input.
- 6Repeat the process for additional inputs whenever you need to. The page stays loaded, so subsequent runs are quick.
Common use cases
- Decode a token to confirm its claims during a debugging session using File Size Converter.
- Format a noisy log line into something a teammate can read.
- Pretty-print a minified blob during incident triage.
- Inspect a payload during local development without writing a script.
- Compare two API responses to spot a regression.
- Convert between data formats while wiring up an integration.
- Validate a config blob before pushing to staging.
- Encode binary content for transport in a JSON body.
FAQ
Binary or decimal?
This tool uses binary units (1 KB = 1024 bytes), matching most OS file size displays.
What about KiB/MiB?
KiB notation is technically correct for binary; this tool labels them as KB/MB for common usage.
How to input?
Enter a number with an optional unit suffix like "1.5 GB" or just a number for bytes.
Private?
Yes — conversion runs locally.
Bits too?
Total bits are shown at the bottom of the conversion table.
Very large files?
Petabyte-scale values are supported; precision may vary for extremely large numbers.
What does the error message in File Size Converter mean?
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is in a supported format and that it is below 0 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Is File Size Converter licensed for business use?
File Size Converter can be used for personal and commercial work alike — there is no separate "business" licence to purchase. The output you generate is yours to use however you want, including in client deliverables, internal documents, or commercial products. Favtoo's only ask is fair, individual use; the tool is not designed to be embedded as a backend service or wrapped behind an API for resale.
Can I use File Size Converter offline?
Once the page is loaded, File Size Converter can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
What is the maximum file size for File Size Converter?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run File Size Converter as often as you need; every run produces a full-quality result.
How often is File Size Converter updated?
File Size Converter is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.
Does File Size Converter require a browser extension or plug-in?
No installation is needed. File Size Converter runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use File Size Converter on any computer you have temporary access to without leaving anything installed on it.
Does File Size Converter work with screen readers?
File Size Converter uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
Does File Size Converter ask for any browser permissions?
File Size Converter only needs the standard web platform — file picker access for the inputs you choose to load, and optionally clipboard access if you copy the result rather than downloading it. There is no microphone, camera, geolocation or background-permission request, because none of those are needed for the work the tool does.