Free Star Map Generator
Most “free star map” sites are storefronts where free means a thumbnail. Here is the actual deal, stated up front.
Open the free generator
Free, in your browser — no account, nothing uploaded. Both downloads are the complete chart: a vector SVG and a 300 dpi PNG, with nothing held back and nothing to buy.
What is genuinely free
- Unlimited maps — every date, place, theme, size and caption option, no cap.
- Both downloads — the vector SVG, and a PNG rasterized at 300 dpi for the page size you picked (5906 × 8268 px at 50×70 cm). Complete charts: nothing obscured, nothing downscaled.
- No account, no email, no upload — the page is static and the astronomy runs in your browser; your data never leaves it. It even works offline once loaded.
What is not free
Nothing. There is no upgrade, no subscription, no feature locked behind a trial, and no checkout anywhere on this site.
This page used to say otherwise, so here is the correction in plain sight: until August 2026 it advertised a high-resolution export you would have to buy one day, and the free file was stamped with a faint diagonal mark to make that future purchase look worthwhile. The purchase was never built. The stamp was therefore doing nothing except damaging your file, so both are gone. What is left is one credit line along the bottom edge — attribution, not a restriction, and you are welcome to crop it before printing.
Then who pays for it?
Nobody has to. It is a static page with no server, no database and no per-visitor cost: the astronomy runs on your device, the star positions come from the public-domain Yale Bright Star Catalogue, and the constellation figures come from d3-celestial (BSD-3). Hosting it costs roughly what hosting a text file costs, which is why it can be free without a catch.
How the map is computed
You give it three things: a date, a time, and a place. For the place, type a town or city name and pick it from the list — 29,919 towns and cities of 18,000 people or more, from GeoNames — or enter an exact latitude and longitude instead. Accents are optional (“malmo” finds Malmö), but type the name on its own: “Roskilde Denmark” finds nothing, and a typo finds nothing rather than the wrong sky.
Your date, time and place are converted to a Julian Date and then to local sidereal time — the astronomer’s clock for “which way is the sky facing.” Each of the 1,630 stars in the Yale Bright Star Catalogue (every star brighter than magnitude 5.0, i.e. every star a good naked eye can see) is transformed to its altitude and azimuth at that exact moment, and every one of those stars above the horizon is projected onto the circular chart: zenith at the centre, horizon at the rim, north at the top — and east on the left, because a star map is read looking up, which mirrors east and west compared to a ground map.
The 89 constellation figures are drawn with the same math and clipped at the horizon. Star dots are scaled by real brightness (magnitude) and tinted by star colour. The Moon is drawn at its real altitude, azimuth and phase for your moment, and left off entirely when it was below your horizon. It does not show the planets, comets or satellites — those wander against the fixed stars and need ephemerides, which this version does not compute. Everything runs in your browser — nothing is uploaded, there is no account, and the page works offline once loaded.
Common questions
Is it really free?
Yes, in full: the generator, every option, and both downloads, with no account and no email. There is no paid tier and none is planned — nothing on this site takes payment or asks for card details.
What is the small line along the bottom of my chart?
A one-line credit, set in the caption colour at roughly the size of the date line: “Made with Starmap” and the site address. It is attribution, not degradation — the chart above it is the complete map at full resolution, with nothing blurred, stamped over or held back. Crop it off before printing if you would rather not have it.
Do you collect my data?
Your inputs, never: there is no backend, no account and no upload, so no server ever sees the dates, places or captions you type — the page is a static file and you can read its source. The published site does run a cookieless pageview counter (GoatCounter) on every page, which records that a page was viewed and not who viewed it; the privacy notice is linked in the footer of the live site.