For most of its history, the singles chart answered a simple question: which record sold the most this week? That was easy to count and easy to understand. Today, the question is closer to “which song was most listened to this week, once all the different ways of listening have been converted to a common unit?” The answer takes more explaining, because the conversion is a set of choices, and those choices shape what appears at number one.
What the chart is made from
The Official Singles Chart is compiled by the Official Charts Company, and the countdown is broadcast on BBC Radio 1 on Friday afternoons. The chart reflects sales of downloads, CDs and vinyl, along with streams of audio and, since a later revision of the rules, of video tracks, on both premium subscription and ad-funded services. Many thousands of retailers, download stores and streaming services supply data each week.
Sales still count, but streaming now does most of the work, which creates a practical problem. A purchase and a stream are very different events. A purchase is a deliberate act with a price attached; a stream may be one of dozens in a day, from a user who has not chosen a particular song. To combine them, the chart needs an exchange rate.
The exchange rate
The rate has changed several times as streaming has grown, and it is worth knowing the shape of it, not just the numbers. In the published rules most widely reported in recent years, a stream from a paid subscriber counts as one hundredth of a sale, while a stream from a user on a free, ad-supported tier counts as one six-hundredth. In other words, 100 premium streams equal one chart sale, and 600 free streams are needed to equal the same.
Earlier versions of the rules used a flat rate, with the same number of streams of either kind counting as one sale. Differentiating between the two reflects an argument that a paid stream represents a more committed form of listening, since the user has paid for the service, while a free stream, though legitimate, is cheaper to generate.
The Official Charts Company has explained the thinking in terms of changing listening habits. Younger fans who may not have a payment card, and fans who cannot afford a subscription but still use legitimate, ad-funded services, are part of the audience, and the rules were designed to keep counting them, at a lower weight.
Why older songs are down-weighted
Another feature of the rules is designed to stop old songs from dominating. Under what the Official Charts Company calls its accelerated chart ratio, a song that has been falling for three consecutive weeks is counted at a higher exchange rate, so that its streams count for less. The reported figures are 200 premium streams, or 1,200 free streams, to equal one sale, in place of 100 and 600. As published, the rule applies only to songs that have been on the chart for a good while, with the earliest it can apply being the tenth week on the Top 100.
The effect is to make room. In the era of unlimited streaming, a popular song can remain very widely played for a long time. Without some mechanism to reduce its weight as it declines, the top of the chart would be slow to change. The accelerated ratio encourages turnover, so that new releases have a realistic chance, and it is one reason a song can slip down the chart sooner than its listening figures alone might suggest.
A related rule limits how much of the chart one act can occupy. As published, the Top 100 includes no more than three singles by the same artist, based on the most popular by sales and streams.
Rules that change
The Official Charts Company reviews its rules from time to time. Over the years it has changed the exchange rate, added video streams from the major platforms and reduced the weight of ad-funded streams. The numbers above are the published ratios as reported by the music industry press and by PRS for Music, and they describe the mechanism more reliably than they describe any particular week. The current ratios and eligibility rules are set out by the company itself, and should be checked there.
How to read a chart position
A chart position can mislead when read without this background. A few observations follow from the rules.
- A number one is a weighted figure, not a headline sales number. Two songs with similar listening can finish in a different order, depending on how many of the streams came from paid accounts.
- Free streams count, but for less. A song that is hugely popular on ad-funded services will register, but not in proportion to its raw plays.
- Longevity is tempered. A song that has been in the chart for months can be heard more than a new entry and still rank lower, because of the accelerated ratio.
- The chart is a measure of specific behaviour. A concentrated push by a fan community, or the release of a physical format, can move a weekly total, and the rules attempt to account for obvious distortions.
Why anyone should care
It is easy to treat the charts as a relic. But they remain one of the few shared reference points in popular music, and they influence how songs are promoted, scheduled on radio and talked about. The rules decide what counts as success, and artists, labels and fans respond to them. If you want to understand why certain releases appear in particular formats, why some songs rise and fade quickly, or why a record gets reissued in several versions, the rules are the best place to look.
It also pays to remember what the chart is not. It does not measure quality, it does not describe everything people listen to, and it cannot capture music enjoyed outside the services it counts. It is a weekly snapshot of a particular kind of attention, counted by a particular formula.
The short version
The singles chart converts sales and streams into a single unit using a set of weights that have changed over time. In the published rules, 100 paid streams or 600 free streams equal a sale, with a faster-decay rule for songs in decline. The chart is a useful guide to what the nation is listening to, provided you remember that the formula, not just the music, is part of the story.
This article is general information. The Official Charts Company revises its rules from time to time; check its website for the current methodology.
Sources: PRS for Music (Big changes coming for UK charts); Music Business Worldwide (Official UK Singles Chart adds video, downgrades ad-funded streams); Hits Daily Double (Limits, ratios and records: singles chart revamped); Official Charts Company
