Lunar Calendar — Moon Phases by Month
View moon phases, illumination, and approximate lunation dates for any month you select.
How it works
- 1Configure your options above
- 2Click "Generate" — processing happens in your browser
- 3Copy or download the result
What to do next
About Lunar Calendar
Lunar Calendar performs lunar calendar as a focused single-page utility. View moon phases, illumination, and approximate lunation dates for any month you select. Defaults are tuned for the common case so the first run is one click, with every option that matters exposed for the moments you need to fine-tune the result.
Anyone who works with web and productivity utility on a casual basis — product managers comparing options, teachers building resource lists, marketers running campaigns — finds Lunar Calendar 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.
The execution path is auditable from the page itself: open developer tools, switch to the Network tab, run a job. The requests you see are static-asset GETs for the engine and the page resources. The actual work is JavaScript code running against the bytes already in your tab's memory.
Architecturally, Lunar Calendar is a single-page client. The processing layer is standard browser APIs; the UI is a thin React shell on top. Inputs flow through the engine and the output is returned to the browser as a Blob you can save or copy. The 0 MB cap is the only hard limit and it exists to keep memory usage stable on every device.
Lunar Calendar 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.
Workflow tip: Lunar Calendar pairs well with Calendar Generator and Holiday Calculator. Other adjacent tools you may find useful are World Clock and UTC Offset Reference. 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.
The download is delivered as a clearly named file the moment processing completes — no email link, no "your result will be ready in 5 minutes" queue, no expiry timer. The file is generated in your browser and saved by your browser's normal download flow.
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.
Some notes on the design of Lunar Calendar. 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.
A short note on how Lunar Calendar came to look the way it does: every iteration started by watching how someone unfamiliar with the tool actually used it, then removing whatever got in their way. That is why the upload area dominates the screen, the run button is bigger than the secondary controls, and the result panel is unmissable when the job finishes.
If you want to get the most out of Lunar Calendar, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
Lunar Calendar 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.
Open the workspace above to start using Lunar Calendar. The engine loads on the first interaction so the page itself stays light, and once the tool is warm it processes subsequent jobs quickly. The moment the page is interactive, the tool is ready to do real work on your file.
How it works
- 1Open the Lunar Calendar workspace above. The interface is a single page, so there is nothing to navigate.
- 2Add your web utility input by dropping it onto the page or browsing for it.
- 3Tweak the controls if the defaults are not quite right for your input. The options are kept short and labelled in plain language.
- 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.
- 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
- Generate a temporary asset for a social post using Lunar Calendar.
- Compare two product variations side by side.
- Create a placeholder image for a wireframe.
- Sanity-check a webhook response while debugging.
- Run a one-off check during a meeting without context-switching.
- Validate a setting before circulating it to a team.
- Audit a marketing page before launch.
- Plan content without paying for a SaaS dashboard.
FAQ
How accurate are the phases?
Astronomical algorithms approximate official almanac times within a few minutes for most locations.
Does location matter?
Phase geometry is global; rise/set times can differ by longitude but phase percent is essentially shared.
Can I export a month?
Copy the rendered table as text or print the page for astronomy club handouts.
Which calendars are supported?
Gregorian civil dates drive the grid; lunar labels follow astronomical convention, not religious calendars alone.
Is my browsing month private?
Yes — selected months never leave your device; no telemetry records which dates you inspect.
Which browsers are supported?
Canvas or table rendering works in Chrome, Firefox, Safari, and Edge on desktop and tablets.
Are there any hidden fees with Lunar Calendar?
Lunar Calendar is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Can I use Lunar Calendar with formats other than the defaults?
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.
What permissions does Lunar Calendar need to function?
Lunar Calendar 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.
Does Lunar Calendar upload my file to a server?
Your file is processed inside your browser by standard browser APIs. The engine reads the file's bytes from your tab's memory, computes the result, and writes the result back into the tab. You can confirm what the page does by opening developer tools and watching the Network tab during a run — the requests you see are for the tool's static assets only.
Can I call Lunar Calendar from a script?
Lunar Calendar 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.
Can I use Lunar Calendar offline?
Once the page is loaded, Lunar Calendar 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.
Why did Lunar Calendar 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.
Does Lunar Calendar reduce quality of the result?
Lunar Calendar 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.
Why does Lunar Calendar 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.