Methodology: how we measure radio

The numbers on Radioguide.fm come from our own systems: stream checks, the song titles stations send with their stream, and listening in our own players. This page describes each measurement and its limits, so you know what a number means before you quote it.

Stream checksNow playingChartsListener numbersRatingsStation factsRadio Report

Stream checks

• Nightly check of every station. Each night we connect to the stream of every listed station, follow playlist files (.pls, .m3u) to the real stream, and read the first kilobytes. A stream passes when it answers within a few seconds with audio. The result and the time of the check are stored with the station (shown as "Last checked").
• Stream monitor. Stations with the stream monitor are checked every few minutes. Each check stores whether it worked, the HTTP status, the audio format and the bitrate the server reports, and the response time. Checks are kept for 90 days.
• Uptime on a station page is the share of successful monitor checks in the last 30 days. We only show it when there were at least 10 checks; otherwise we show the result of the last check.
• Stream quality (format and bitrate) comes from the stream server's own headers at the last check, or, for stations imported from the open Radio Browser database, from that database.
• Limits: a check shows that the server sends audio at that moment, not that every listener in every country can play it (some streams are blocked by region or by browser).

Now playing

• Many stations send the current song title with their stream (ICY metadata). We read that title regularly for each station; when a stream sends no title we ask the stream server directly (Icecast and Shoutcast status pages).
• Each change of title is stored with the time it was seen. Titles are cleaned up: "feat." artists are separated, additions such as "Radio Edit" are removed, and adverts, jingles and station messages are filtered out by pattern.
• The first title we see after we start following a station is not counted as a play, because we do not know when it started.
• Limits: stations that send no titles, or only the programme name, are not in the data. A title shows what the station says it plays; we do not analyse the audio.

Radio charts

• A play is one song title seen on one station. Raw plays are kept for 14 days; every hour they are added up into daily totals per song, country and genre, which we keep.
• Charts rank songs and artists by the number of plays in a period (the last 7 days unless stated otherwise), worldwide, per country (the station's country) and per genre (the station's main genre).
• The number of stations for a song counts distinct stations. For very widely played songs this is a lower bound, because each daily total keeps at most 50 station ids.
• Song and artist pages are only indexed by search engines from 3 (songs) and 5 (artists) plays in 30 days.
• Limits: charts measure airplay on the stations in our data, not sales, streams on music services or audience size. Stations that repeat songs often weigh more than stations with a wide playlist.
• Weekly chart positions on artist pages are the artist's rank by plays in each finished week (Monday to Sunday, UTC) among the top 200 artists.
• Artist details such as country, active years and genres come from MusicBrainz (open data, CC0), only when MusicBrainz has exactly one artist with the same name.

Listener numbers

• Our players (station pages, embedded players on other websites and Radioguide Channels) report when someone starts listening and, while they listen, the listening time about once a minute.
• Listeners are unique visitors who started a station, counted per day and per month. To count them without tracking anyone, a visitor is a one-way code made from the network address and browser, mixed with a secret that changes every day and every month and is then deleted. We do not store network addresses. Unique counts use a statistical method (HyperLogLog) with a small error margin.
• Abuse is capped: a visitor counts for at most a set number of plays and listening hours per day, and the listening time one report can add is capped.
• Limits: these numbers only include listening through Radioguide, not a station's total audience on FM, DAB, apps or its own website.

Ratings and reviews

• Listeners rate a station from 1 to 5 stars with one tap. One rating per station per visitor per day counts; rating again on the same day changes the earlier rating. There is also a daily limit per visitor for all stations together (20).
• A short text is optional. Every text is checked by our team before it appears; a basic filter marks texts with links, swear words or shouting for extra attention. We remove spam, insults, personal data and texts that are not about the station, never a review only because it is negative.
• The average rating counts all approved ratings. Stations show a rating in search results (structured data) only from 3 approved ratings.
• Verified station owners can reply publicly to reviews.
• So far listeners have left 26,911 ratings.

Station facts

The facts table on a station page combines: country, city, genres and website from the station's details (entered by the station, our team or imported from Radio Browser); stream quality and uptime from the stream checks; listeners this month from our listener numbers; the most played songs and artists of the last 7 days from now-playing data; similar stations that played the same artists this week (or, without play data, popular stations with the same genre in the same country); "Owner verified" when the owner completed a claim. Facts we do not have are left out. Every station also has a plain text version of its facts at /internet-radio-<country>/<station>/facts.txt.

Radioguide Radio Report

On the first day of each month we publish the Radio Report for the previous calendar month, built from the data above: most played songs and artists, the fastest risers compared with the month before, the most listened stations on Radioguide per country, and stream reliability. Quotes from the report may be used with a link to the report page.

Questions about a number? Mail [email protected]. See also our editorial policy.