Who’s behind it
Mapsfera is an independent project. It doesn’t belong to any government agency or to any of the sources whose data it uses: we just credit them.
Pages are signed by the Mapsfera Team. We don’t list individual names or job titles: the team as a whole stands behind everything we publish, and you can reach it through the contact form. Our terms of use are on their own page.
What the byline means
Under the title of every tool, guide, blank map, quiz, place page and size comparison you’ll see “By the Mapsfera Team · Last reviewed…”. That date is the last day we reviewed the page’s content: the text, the data and the math. We update it by hand when we review the page; a design or code change that doesn’t touch what the page says doesn’t move it.
Guides also show when they were published and, if they explain steps on another site (like Google Maps), the day we checked those steps.
How we choose what to build
- Real tasks. We start from what people search for: finding their elevation, converting coordinates, measuring a distance, printing a blank map. We look at search data and at what already exists, and we build a tool when we can do that task better: in your language, with your country’s data or in fewer steps.
- Only with data that allows it. A tool ships only if there’s open, reliable data to do it right, under a license that lets a site like this one use it. If a source requires a license for commercial use, we don’t use it, which is why we don’t use Eurostat’s GISCO boundaries.
- Language doesn’t change the country. A US tool uses US data and units in Spanish too, and a tool for Spain uses Spain’s data and units in English too.
- Pages with their own content. We only make a page for a map, a quiz or a place if it has its own data to share, not the same text with a different name. If it doesn’t, we fold it into another page.
Where the data comes from
From official, open sources. In the US, the Census Bureau, the US Geological Survey (USGS) and the National Park Service; in Spain, the National Geographic Institute (IGN), the National Statistics Institute (INE) and the land registry (Catastro); worldwide, OpenStreetMap, Natural Earth, the World Bank and the NOAA/BGS World Magnetic Model, among others.
- Every tool lists its data sources at the bottom of the page, with a link to each one.
- Our methodology explains how each figure is calculated and how accurate it is, and its sources table lists every license.
- The data behind the tools, maps and place pages comes from the source files: scripts read them and prepare them for the site, with no numbers copied by hand. When a source has a typo and we fix it, we log it on our corrections page, which also lists the version of each dataset (which census estimates, which year).
- When a tool needs live data (an elevation, an address, a route), your browser asks the public service that provides it, and each tool says which one.
How we check the figures
With automated tests: programs that run the same math as the site and compare the results with reference values, published by the sources or calculated with reference software. We run them every time we change that math or that data, and if one fails, we fix it before publishing. Here’s what they check:
- Coordinates and national grids: 501 cases calculated with PROJ 9.8.1, the coordinate transformation software behind QGIS and most GIS; for US State Plane, 693 PROJ cases and 205 from the NGS’s official converter (NCAT), zone included; MGRS, Plus Codes and geohash, against their official or reference libraries.
- Sun and moon: 4,878 sunrise and sunset times for 2026 from the US Naval Observatory (USNO), 1,460 from Spain’s National Astronomical Observatory (OAN), twilight times, moonrise and moonset, the 2026 moon phases and NASA’s eclipse catalogs. The largest difference is 1 minute.
- Magnetic declination: the official test values of the World Magnetic Model 2025, the 12 points in its technical report and the 100 in its long table.
- Time zones: well-known places on both sides of time zone borders (Indiana, Kentucky, Arizona and the Navajo Nation, among others) and daylight saving time changes.
- Map lines: the tilt of Earth’s axis (IAU 2006 formula) against SOFA, the International Astronomical Union’s reference library, and the countries each line crosses against Wikipedia’s lists.
- Blank maps and quizzes: that each country has the divisions its page lists and each US state has the Census Bureau’s counties; that each country’s area is close to the World Bank’s and each county’s within 3% of the Census Bureau’s; and that names and capitals are there.
- Place pages: in Spain, each elevation against the IGN’s MDT05 terrain model at that point; in the US, against the USGS 3DEP and the last GNIS figure; and the UTM coordinates recalculated.
- Profiles, comparisons and search: the climb of sample profiles and the reading of MDT05 clips; that the areas and population in each size comparison match their sources and that “fits N times” is the division; and 139 real place searches, with what should come first.
- Thematic maps: that municipalities and counties add up to their provinces and states, the figures the INE published in its income atlas press release, and 5 municipalities and 5 counties checked by hand on the INE and Census Bureau websites.
- Map files: real files from Google My Maps, Google Earth, Garmin, Wikiloc and QGIS, and that converting between KML, KMZ, GeoJSON and GPX loses nothing.
- Other calculations: bearings, the horizon, the tunnel through Earth (with the PREM model), centers and random points, with edge cases (the antimeridian, the poles, exact antipodes); the check letters of Spanish cadastral references; and that moving a country around the map doesn’t change its area.
Not everything can be tested this way. What a live service returns (a route, an address, an elevation) depends on that service at that moment: each tool says so, and our methodology explains how accurate to expect it to be.
How we use artificial intelligence
We use AI tools to write the site’s code and the text on its pages, in both languages. We’re telling you so you know how it’s made.
What AI doesn’t do is supply the figures. The ones the tools, maps and place pages give you (elevations, populations, areas, coordinates, times) aren’t written by a model from memory: code calculates them from the sources’ data, and we check them with the automated tests above. Figures quoted in the text (say, how many counties the US has) must come from that same data or from a credited source; if you spot one that doesn’t add up, let us know.
The tools don’t use AI either: the result you see is calculated by code in your browser (or by the public service we credit), always the same for the same data.
The team is responsible for everything we publish. We review what goes out and, if something’s wrong, we fix it and log it on our corrections page, wherever the mistake came from.
How we correct mistakes
- Every tool has a “Spotted a mistake? Let us know” link that opens the contact form with the page already filled in. You can also write to us from our contact page.
- We check it against the source or by redoing the math.
- If it’s a mistake, we fix it, update the page’s review date and log it on our corrections page with the date, the page and what changed.
- Data updates (new population estimates, new boundaries) aren’t corrections: they show up in the data versions on that same page.
Independence and advertising
- No one pays to be on Mapsfera. We don’t publish sponsored content or paid articles, and no tool, source or link is here because someone paid for it.
- There are no ads today. If ads come, they’ll go on content pages and never inside a tool, a map, a quiz or a printable sheet, as we explain in About Mapsfera. Advertisers don’t decide what we publish or what it says.
- Affiliate links. If we ever link to a store with a link that earns us a commission when you buy, we’ll say so next to the link.
How often we review
- When a source changes. When a new version of the data comes out (Census Bureau estimates and Spain’s municipal register, every year; IGN boundaries, when they change; the magnetic model, every five years), we add it and review the pages that use it.
- When you tell us about a mistake or a step that has changed on another site.
- What depends on the year updates itself: the latitude of the tropics and polar circles is the current year’s, and the tests warn us if the map line data is more than 10 years old.
- At least once a year we go over every page: that the data is still current, the links work and what it explains still holds.
The date in the byline tells you when each page was last reviewed.
Get in touch
If something looks wrong, a source is missing or you want to know how we do something, write to us through the contact form. More about the project in About Mapsfera.