Holiday Calculator — Business Days Between Dates
Compute business days between dates while skipping weekends and a configurable holiday list.
How it works
- 1Enter your values in the fields above
- 2Click "Calculate" — all math runs in your browser
- 3View your results instantly
What to do next
About Holiday Calculator
Holiday Calculator is part of a collection of single-purpose web and productivity utility tools. Compute business days between dates while skipping weekends and a configurable holiday list. Each tool is intentionally narrow — it does one thing well rather than offering many overlapping features — which makes the common path predictable and the result easy to verify before you download or copy it.
The processing pipeline is straightforward: your input is parsed by standard browser APIs, transformed according to the options you select, and serialised back into a downloadable result. The 0 MB per-file ceiling matches what a typical browser tab can handle without paging to disk.
Holiday Calculator is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
Holiday Calculator is structured so the question "where is my file processed?" has a single answer: in your browser tab. The engine, the controls, and the result panel are all on one page. Navigating away or closing the tab clears the page's memory the way it does for every other tab.
A practical note on limits: Holiday 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.
Holiday Calculator fits naturally next to several adjacent tools. Common companions include Calendar Generator, Lunar Calendar, DST Checker, and Meeting Timezone Planner — combine them when the job needs more than one transformation. After running Holiday Calculator, many users move on to Calendar Generator and Lunar Calendar. Each tool is a separate page so you can compose the exact pipeline you need.
Holiday Calculator sees the most use from creators experimenting with formats and product managers comparing options, 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.
Output handling is intentionally boring: Holiday Calculator 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.
Some notes on the design of Holiday 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.
From a product perspective, Holiday Calculator is one of the simplest possible expressions of "do one thing well." The catalog contains dozens of related tools that each handle a slightly different web and productivity utility task, and every one is a separate page rather than a tab inside a larger app. That separation keeps each tool fast to load and easy to bookmark.
A few practical tips that experienced users of Holiday 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.
Holiday Calculator fits the gap where opening a desktop app feels heavy and writing a script feels overkill. The page handles the common web and productivity utility task with sensible defaults so a single visit usually completes the job; for highly specialised work, a dedicated desktop application can offer more knobs to turn.
If Holiday Calculator appears to hang, the engine is almost certainly still working — large inputs simply take longer to process inside a browser than they would on a server with multi-core scheduling. For inputs near the 0 MB cap, give it up to a minute on a typical laptop before assuming something is stuck.
If Holiday Calculator 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 Holiday Calculator in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Drop a web utility file onto the upload area, or click to pick one from your device.
- 3Tweak the controls if the defaults are not quite right for your input. The options are kept short and labelled in plain language.
- 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.
- 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.
- 6Run additional jobs as needed. The same controls and defaults apply on every run.
Common use cases
- Generate a temporary asset for a social post using Holiday Calculator.
- Plan content without paying for a SaaS dashboard.
- Run a one-off check during a meeting without context-switching.
- Create a placeholder image for a wireframe.
- Validate a setting before circulating it to a team.
- Preview how a result looks before deploying it.
- Audit a marketing page before launch.
- Sanity-check a webhook response while debugging.
- Generate a campaign asset in seconds for a quick test.
FAQ
How do I add holidays?
Paste ISO dates (YYYY-MM-DD) one per line or pick from a small preset list for common US observances.
Are weekends excluded?
Yes by default — Saturday and Sunday do not count; toggle if your organization uses different rules.
Is the result inclusive?
Choose inclusive or exclusive endpoints depending on whether start and end days should count.
Does it handle half-day holidays?
Half days are treated as full holidays for simplicity; adjust manually if you need partial credit.
Is my date range private?
Yes — arithmetic runs locally; payroll or PTO dates you enter are never transmitted to us.
Which browsers are supported?
Plain JavaScript date math works in all modern Chrome, Firefox, Safari, and Edge versions.
Does Holiday Calculator reduce quality of the result?
Holiday Calculator is built to preserve quality wherever the underlying web utility format allows it. Operations that are mathematically lossless (e.g. structural transformations, lossless re-encoding) round-trip with no perceptible change. Operations that involve a lossy codec inevitably introduce small artefacts at the byte level, but the defaults aim at the sweet spot where output looks or sounds the same to a normal viewer or listener while still being meaningfully smaller or faster than the input.
What is the maximum file size for Holiday Calculator?
Inputs are capped at 0 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run Holiday Calculator as often as you need; every run produces a full-quality result.
Can Holiday Calculator run inside a corporate firewall?
Holiday Calculator is a static page running an open-source engine in your browser, so a typical corporate firewall does not get in the way as long as it allows JavaScript to load from Favtoo. For teams that need to host it themselves on an internal network, the underlying engine (standard browser APIs) is open-source and can be packaged into a private build with the same behaviour. Reach out via the Contact page if that is something you are exploring.
Is there a desktop version of Holiday Calculator?
No installation is needed. Holiday Calculator 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 Holiday Calculator on any computer you have temporary access to without leaving anything installed on it.
What input formats are supported by Holiday 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.
Does Holiday Calculator have an API?
Holiday 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.
Why did Holiday Calculator reject my input?
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.
Can I use Holiday Calculator on iOS or Android?
Holiday Calculator runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 0 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.
How do I run Holiday Calculator over a folder of files?
Holiday 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.