What do Korean Drama ratings mean? The hidden power behind viewership ratings

The competition for viewers is a fierce battle between television networks in Korea.

Korean dramas have always gained the interest of audiences all over the world, from the signature heart-wrenching romance dramas to the rise in popularity of various genres today. The concept of Korean drama no longer needs to be explained in detail because it is already “learned by heart” by those who are Korean drama addicts. 

In Korea, the audiences have to pay to watch the dramas they love.

The “Big 3” of Korea’s national television networks, KBS, SBS and MBC, along with some popular cable broadcasting networks like Mnet or tvN, always compete in a fierce battle to attract viewers. The ratings wars are becoming more and more intense because it not only determines the success or failure of a drama but also the existence of a broadcasting company. Every month, a household in Korea pays about 7,000 won ($7) to watch TV. In order to win the hearts of the audience and reap huge profits, producers all have to compete for viewership ratings.

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What are ratings?

Although viewers often base their choice to watch a series on its high ratings, not many people actually understand the meaning of Korean drama ratings. Does having high ratings really mean the drama is the most popular and has the highest number of viewers?

Rating is the average number of viewers at a time of broadcast. For example, the drama “Boys Over Flower” recorded a rating of 31% which means that at that time, there were a lot of shows on air but up to 31% of viewers were watching this drama.

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The rating is calculated by a special device attached to the TV. Every time viewers switch channels, this action will be saved in memory, then transferred to the center for calculation and public announcement.

Based on the rating, the producers and experts can assess the performance of each production, whether it is loved by the audience or not. Because in Korea, the producers film the drama, edit it, then broadcast right after, so the rating is clearly important. High ratings can be a huge source of encouragement. On the other hand, low ratings obviously can discourage the entire production crew.

It’s like when we cook for someone, of course we would think of those who will be enjoying our food, so taking account what viewers want is undoubtedly the number 1 priority for the television networks. In Korea, two companies that have publicly provided TV rating information since 2000 until now are AGB and TNS. Measuring ratings is extremely crucial for broadcasters and producers because it governs two main factors: viewers and commercials.

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In terms of viewers, rating is a measure of their taste. It is important for the producers to verify the viewers’ tastes, which dramas they are enjoying the most and which ones they are turning their backs on. Without ratings, TV networks will only produce and broadcast the shows they think and expect the audience to watch, without being able to foresee the future development of dramas that last up to 100 episodes.

Commercially, broadcasters can control the effectiveness and adequacy of the advertising deals they offer to businesses. Of course, large businesses will want their products to be promoted during prime-time slots with the most viewers. Thus, the advertising price will be divided accordingly. Based on some statistics, businesses are also aware of the audience their products are aimed at and even maintain or shorten the total length of a broadcasting drama. 

How to check ratings?

AGB or TNS conducts a survey of the viewership ratings in many big cities with large populations such as Seoul, Busan, Daegu, Daejeon, Kwangju, etc.

Before conducting the rating survey, companies make preliminary statistics on the number of televisions that a household owns, income, gender, and age of family members for about 30,000 households in the area, then select a small number of households that are representative of the national viewers.

After the panel households have been selected, the rating agencies use a measuring device called People Meter attached to receptors in television sets in different areas nationwide.

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Thus, at any time, the information of which person, male or female, at which age watches which program is transmitted to the data processing center of the investigation companies. The rating agencies will use the collected data to calculate the ratings of the programs. The higher the rating, the higher the number of viewers, the greater the interest in the programs.

The power of ratings

If box office revenues are the parameter of a film’s success, for dramas, the rating is the standard scale. Audiences are also the ones who clearly benefit from the numbers of ratings. They get to watch the most popular dramas instead of risking their time to watch a boring one, with no guarantee of its quality.

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Currently, in Korea, it can be divided into two kinds of drama production. The first case is the broadcasting companies directly produce, then broadcast the dramas on their TV channels. Second, third-party production companies produce and then resell to TV stations. Most dramas nowadays are produced in a second way.

For dramas produced by third-party studios, the TV networks will calculate the production costs, the costs for the cast and crews (directors, actors, etc.) of each episode and then pay the production companies. In other words, the broadcasting companies buy the dramas from the production companies. Prices for an episode vary widely, ranging from 5 million won (approximately 5,000 USD) to 100 million won.

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If the drama has a high rating or has not even been broadcast yet, but is already getting attention thanks to the cast, director, and screenwriter, attracting many clients to buy the broadcasting rights, the TV networks will be the first to profit off the copyrights on the grounds that they spent money to purchase the dramas to broadcast, so they have the right to sell them. This right of preference lasts for about 2~3 years, and during that time, the production companies cannot sell the dramas at their discretion. However, if the production companies sell the dramas, they must split the profit with the broadcasting stations.

In addition, if during the making of the drama, a separate set is needed, the producers will proceed with the construction. After that, it is possible to make a profit by turning the set into a tourist attraction. Typically, the romantic set in the 2002 hit drama Winter Sonata used to become a favorite area for tourists in Korea.

Ratings also determine the production cost for an episode. If the episode with the highest rating (among the dramas aired at the same time), the production cost up to 150 million won/episode will be paid. Moreover, a drama with high ratings also means that the advertising prices prior to its showtime will be more expensive.

With a drama with a high rating, the crew and cast will become more well-known and their media coverage will be boosted. Actors, directors, writers and producers of the most-viewed dramas will receive more offers following the success of their works. 


With the tough competition of many TV channels at the same time, dramas nowadays witnessing a decrease in average ratings is considered a somewhat inevitable consequence. A drama dominating the market share with a rating of 50% like First Love (2017) is unlikely to happen again. However, there is no denying the fact that the ratings also bring an opposite effect, that is, the race for high ratings has made many producers busy following the tastes of the audience while ignoring the importance of the plots and storylines, even trying to cover it up with a famous cast.

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While in many countries, viewership ratings are still a far-fetched, unrealistic concept, this is the bait of Korean major broadcasting companies. Although this number does not fully reflect the good – bad quality or success of a production, history has proven that the dramas with the highest ratings ever are all great and well-loved works.

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