If you ask which line on the Seoul subway is the busiest, your impressions and annual statistics may look a little different. Comparing the 2025 figures in the CSV of Seoul Subway Congestion Statistics at Seoul Open Data Plaza, Line 9 was the highest at 182.5, followed by Line 8 at 159.4 and Uisinseol Line at 153.2. This article does not just use these three figures as a ranking, but also points out how to interpret them when choosing a route to work, appointments, or travel.

Conclusion first: Top 3 most congested routes in 2025

The 2025 line provided includes values for 11 routes, including Seoul Transportation Corporation Lines 1 to 8, Seoul Metro Line 9, Ui New Urban Railway, and Sillim Line. As a result of sorting these values ​​in descending order, 1st place is Line 9 with 182.5, 2nd place is Line 8 with 159.4, and 3rd place is Uisinseol Line with 153.2. Line 2, ranked 4th, is 150.4, 3.2 difference from 3rd place.

Rankings are limited to annual statistics for 2025. This means that it is not a real-time ranking, which refers to the congestion on a given Monday morning or immediately after a performance. Even within the same route, the experience can vary greatly depending on the time of day, direction, and station, so it is more accurate to read these results as a starting point for identifying “routes with relatively high crowding.”

  • 1st Line 9: 182.5
  • 2nd Line 8: 159.4
  • 3rd place Uisinseolseon: 153.2
  • 4th Line 2: 150.4 — Values to compare with the top tier

1st place Line 9 182.5: The numbers tell the difference between the top ranks

Line 9's 182.5 is 45.5 higher than this CSV's overall 2025 average of 137.0. Based on the overall average, it is about 33.2% higher and is 23.1 different from Line 8, which ranks second. This is why among the top three, the value of line 9 is the most clearly ahead.

This difference does not mean that Line 9 is always the busiest for all sections and all trains. In particular, Line 9 is a route that requires separate confirmation of train type and stopping pattern, so when actually boarding, priority should be given to the app's real-time route and platform electronic display. It's good to think of statistics as telling you the overall pressure on the line, and on-site guidance telling you which train to take now.

2nd Line 8 159.4: 22.4 higher than average

Line 8 was 159.4 in 2025, 22.4 higher than the overall average of 137.0. This figure is approximately 16.4% higher than the average. Although it is different from Line 9, it is a route that needs to reflect congestion in the schedule as it is the second highest value among the 11 routes subject to analysis.

However, there is no need to immediately fixate on an avoidance course after seeing high annual numbers. Adding one more transfer or making a major detour to your destination can actually make the entire trip more inconvenient. If the appointment time is important, it is realistic to move the departure time a little earlier, and if there is a baby car or carrier, compare the number of transfers and the elevator movement route.

3rd place Uisinseol Line 153.2: Why small routes should be viewed separately

Uisinseolseon was third with 153.2. It is 16.2 higher than the overall average and 2.8 higher than Line 2 in 4th place. Contrary to the impression that “only the main trunk lines are crowded,” this data also places the Uisinseol Line at the top. If you look at the values ​​for each route together, you can see differences that are easy to miss just by feeling.

However, since this statistic presents the entire route as a single value, it does not isolate congestion at specific stations, in specific directions, or at specific times. Check real-time directions by entering your destination station and time zone before departure, and even choose to send a vehicle on site to travel safely and comfortably.

  • Annual statistics show major trends along the route.
  • To determine actual boarding, you must re-check the time zone, direction, and train type.
  • It is better to compare the entire route rather than blindly taking a detour just because it is a high-ranking route.

Why is Line 2 not in the TOP 3: Read 150.4 together

Line 2 is often cited as the Seoul subway's most congested line, but in the 2025 annual figures provided, it ranks fourth at 150.4. The difference from the Uisinseolseon 153.2 is only 2.8. Therefore, it is more appropriate to read it as a route that is on the border of the top tier, rather than saying, “It is quiet because it is not in the top 3.”

This result does not mean that your perception is wrong. Line 2 is a circular line and can be very crowded depending on the commercial area, transfer station, and commute direction. This ranking does not determine the inconvenience of a specific route, but is the result of comparing 11 routes within the same annual index. To make judgments by station and time zone, more detailed data is needed.

What can be changed in actual movement when the number is high

Congestion doesn't necessarily mean you have to avoid the top routes. Instead, you can change small choices like avoiding last-minute transfers, picking a departure time that allows you to send a ride or two, and avoiding crowds at the door on the platform. Especially if you have large luggage or your companions walk slowly, compare routes with simple transfers first rather than the shortest time.

On days where lateness costs are high, such as appointments or airport transfers, real-time driving conditions take priority over congestion statistics. Use the rankings in this article as reference information before departure, and check train intervals and detour routes on the map app, operating agency notices, and station electronic displays on the day. Distinguishing between the roles of statistics and real-time information is the safest way to use it.

Calculation method and limitations of this ranking

The rankings were calculated by sorting the 11 route values in descending order from the 2025 rows of the provided CSV, excluding the “Average” column. The raw data only contains route congestion by year, so there is no detailed explanation of time zone, direction, station values, or calculation method in this CSV. Therefore, this article does not translate the numbers into seat occupancy or real-time passenger numbers.

The data also covers 11 routes presented as columns in the CSV. This should not be generalized as a complete ranking of all railway lines passing through Seoul. As the timing and scope of data update changes, the ranking may also change, so subsequent judgments should be made both by checking the original data page and the latest public data.

  • Analysis criteria: to 2025, excluding “average”, comparing 11 routes
  • Top 3: Line 9 182.5, Line 8 159.4, Uisinseol Line 153.2
  • Note: This is not a real-time congestion ranking by station or direction.
  • Use: Reference information for determining departure times and transfer allowances

Frequently Asked Questions

What will be the busiest Seoul subway line in 2025?

In the 2025 value of the Seoul subway congestion statistics CSV provided, Line 9 was the highest at 182.5. This is followed by Line 8 at 159.4, and Uisinseol Line at 153.2.

Is Line 9 always the busiest?

No. These rankings are annual route-level statistics. Actual congestion will vary depending on time of day, direction, station, and train type, so you should check real-time information on the day.

Is it better to avoid highly congested routes?

There is no need to avoid it at all costs. It is more practical to compare overall travel time, number of transfers, luggage, and appointment times together, and to allow ample time for departure.

Data sources and analysis criteria

The rankings and figures in this article are the result of self-sorting based on the 2025 CSV row of the “Seoul Subway Congestion Statistics” provided by Seoul Open Data Plaza. These are annual route statistics, so please do not interpret them as real-time or station-specific congestion information.