BCD — Four bit decades
decimal ↔ packed BCD nibbles
How it works
- 1Type or paste in the decimal or bcd nibbles field
- 2Conversion happens instantly in your browser
- 3Copy the result with one click
What to do next
About BCD Calculator
BCD Calculator is the kind of utility you bookmark and reach for when you need it. decimal ↔ packed BCD nibbles. It loads quickly, works on any modern browser, and produces a result you can download or copy in a single click.
Reach for BCD Calculator when you need a predictable result on a single file. The page works on the first visit, the controls are visible without a menu, and the output is delivered the moment the engine finishes.
BCD 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.
BCD Calculator is implemented on top of standard browser APIs. Inputs are read from the file picker or drop zone, decoded in the browser, processed, and re-encoded into the output format. Files up to 0 MB are well within the comfort zone of any modern browser.
A practical note on limits: BCD Calculator accepts inputs up to 0 MB per run, and the tool processes one input at a time to keep memory usage predictable. If you ever bump into the ceiling, the cause is the size of the input.
Anyone who works with calculation on a casual basis — hobbyists planning DIY projects, finance teams modelling scenarios, engineers sanity-checking conversions — finds BCD Calculator a quick way to get the result. The page loads in under a second, the controls are visible from a single screen, and the result downloads or copies in one click.
BCD Calculator returns the result as a download. 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.
BCD Calculator sits in a small group of related tools. Useful neighbours include Octal to Decimal Converter, Decimal to Octal Converter, Binary to Hex Converter, and Hex to Binary Converter. They are designed to compose: the output of one is a sensible input to the next, so a multi-step task is usually a sequence of single-click operations.
Some notes on the design of BCD 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.
Some context on why BCD Calculator exists in this form: modern File APIs, high-performance JavaScript engines, and well-maintained open-source libraries now make it possible to perform calculation work entirely in the browser. BCD Calculator is built on top of that capability, which is why a single page can host the full pipeline.
BCD Calculator produces deterministic output: the same input plus the same options always produces the same result. That predictability matters when the result has to match an upstream specification or be reproducible later.
A few practical tips that experienced users of BCD Calculator pick up over time. First, keep your default browser updated — the engine relies on standard web APIs and newer browser versions are noticeably faster than ones from a few years ago. Second, close other heavy tabs before processing a large input; the engine shares CPU and memory with whatever else is open. Third, if you re-run the same kind of job often, your last-used settings are remembered for the rest of the tab session, so subsequent runs are essentially one click.
If the result is not what you expected, the most common causes are easy to check. Confirm the input is under the 0 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.
BCD 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.
How it works
- 1Open the BCD Calculator workspace above. The interface is a single page, so there is nothing to navigate.
- 2Select the calculator 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.
- 4Click to start the job. The engine (standard browser APIs) processes the input in the page; you can watch the progress indicator until it completes.
- 5Download the result. The file is generated in your browser and saved through your normal download flow.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Work out a percentage change between two figures using BCD Calculator.
- Forecast a fitness target without a paid app.
- Sanity-check a quote before sending it to a customer.
- Confirm a unit conversion before quoting it in a report.
- Check the maths in a homework answer.
- Compare two scenarios side by side without spinning up a spreadsheet.
- Convert a foreign currency amount into your local one.
- Estimate how much paint or material a room will need.
- Split a restaurant bill cleanly between a group.
FAQ
How do I use the BCD Calculator?
Type a value with the unit shown in the placeholder, pick direction if offered, and read the multi-line equivalents output.
Is this bidirectional?
Yes — toggle forward and reverse where supported so either side can drive the conversion.
Are big integers supported?
Binary, hex, octal, and decimal integer tools use BigInt parsing where needed for large values.
Is data uploaded?
No — conversions execute locally in your browser session.
What if I get a format error?
Match spacing and unit tokens closely; most errors mean the parser did not recognize the pattern.
Can I copy results?
Yes — select the output text and copy like any normal web page.
Are there any usage limits on BCD Calculator?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run BCD Calculator as often as you need; every run produces a full-quality result.
What input formats are supported by BCD Calculator?
The accepted formats are listed in the upload area on the tool itself. If your input is in a format that is not directly supported, convert it first using one of Favtoo's converter tools — every Favtoo converter outputs a file that is a clean input to the next tool in the chain.
Why use BCD Calculator instead of a paid online tool?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. BCD Calculator sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common calculation operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Which browsers are supported by BCD Calculator?
BCD Calculator works in any modern browser released in the last few years — Chrome, Edge, Firefox, Safari, Brave, Arc and the major Chromium derivatives are all supported. The underlying engine relies on widely-supported web APIs, so there is nothing exotic to install. If you are on a very old browser version and the tool fails to load, updating to the latest release of your preferred browser is the only fix needed.
How do I run BCD Calculator over a folder of files?
BCD Calculator processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Does BCD Calculator have an API?
BCD Calculator is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
Will BCD Calculator keep working if my Wi-Fi drops mid-task?
Once the page is loaded, BCD Calculator 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.
Does BCD Calculator work with screen readers?
BCD Calculator 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.
Why does BCD Calculator feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 0 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.