What is being compared
Run SEA keeps the official results of 75 recent races and an archive of earlier editions for 35 of them: 52 past editions with 199,099 finishers, going back as far as 2019 [1]. For 31 races, the archive has at least one earlier edition to set against the latest one. The counts here are finishers in the 10K, half marathon and marathon, as listed by the timing company. They are not entries, and 5K, fun-run and other distances are not counted.
Taken together, those 31 races had 88,050 finishers at their previous edition and 93,546 at their latest, up 6% [1]. That headline is almost entirely the Manila Marathon. Without it, the other 30 races went from 73,668 finishers to 72,702, down 1%, and 15 of the 31 races grew while 16 shrank.
Runners are moving up a distance
The clearest pattern is not in totals but in distances. In the 30 races that held a 10K at both editions, 10K finishers fell 13%, from 46,172 to 40,088. In the 29 with a half marathon at both, half-marathon finishers rose 21%, from 34,531 to 41,628. In the eight with a marathon at both, marathon finishers rose 37%, from 7,347 to 10,060, although the Manila Marathon supplies most of that rise [1].
The PUMA Philippine Half Marathon Series shows it most cleanly. At its Cagayan de Oro, Cebu and Clark legs, total finishers barely changed between 2025 and 2026, but the half marathon went from 470 to 1,100, from 445 to 1,125 and from 881 to 1,356, while the 10K fell by a similar number at each [1]. The same runners, or the same number of them, chose the longer race.
The risers
The Manila Marathon is the fastest-growing race in the archive. Its marathon had 431 finishers in October 2024, 2,827 in August 2025 and 5,744 in June 2026. Across all three distances it went from 4,421 to 14,382 to 20,844 finishers in two years [1].
The PUMA series' Manila leg nearly doubled, from 5,135 finishers in 2025 to 9,751 in 2026, with the half marathon rising from 2,371 to 6,166 [1].
Vietnam's races are growing steadily. Techcombank Hanoi International Marathon went from 5,479 finishers in 2024 to 8,607 in 2025 and 9,491 in 2026, and its marathon field from 1,110 to 1,975. VPBank Dat Sen Hong Music Marathon in Dong Thap went from 1,412 finishers in 2022 and 2,827 in 2023 to 5,997 in 2026, and Garmin Run Vietnam from 3,608 to 4,839 in a year [1].
In Indonesia, Crystalin Run Xperience in Jakarta grew from 1,890 to 2,934 finishers, with its half marathon more than doubling from 494 to 1,069 [1].
The fallers
Laguna Phuket Marathon has the longest record in the archive and the clearest long decline. Its marathon had 2,231 finishers in 2019, 1,049 in 2022, 979 in 2023, 851 in 2024, 595 in 2025 and 603 in 2026. The half marathon fell from 3,689 in 2019 to 1,737 [1]. The race as a whole grew 19% between 2025 and 2026, helped by a 10K, which appears in the archive only from 2024, but its headline distance is a quarter of its pre-pandemic size.
Khun Dan Marathon, at the Khun Dan Prakan Chon Dam in Nakhon Nayok [2], had 3,132 finishers in 2019, 1,599 in 2024, 2,232 in 2025 and 1,880 in 2026 [1].
In the Philippines, Discovery Marathon fell from 1,687 finishers to 971, with its marathon halving from 471 to 230. Isla del Fuego Marathon on Siquijor went from 1,528 in 2024 to 2,915 in 2025 and back to 1,766 in 2026. HOKA Midnight Run's Cebu leg fell from 2,138 to 1,049, and Takbo para sa Kalikasan has fallen each year, from 3,907 to 2,775 to 2,422 [1].
The steepest drops are at the five city races of the Sante Barley Trilogy Run Asia's third leg in Manila, Cebu, Cagayan de Oro, Davao and Iloilo, down between 61% and 83% from 2025 in the half marathon and 10K. That needs the biggest caveat of all: each city's third leg in 2026 was headlined by a 32 km [2], which is not in either year's count, so these figures may show runners moving to the 32K rather than leaving the race.
Why to read these numbers carefully
Finishers are not entrants. A hot morning, a tight cut-off or a course problem cuts the finisher count without anyone staying away. Results pages can also be incomplete, and a timing company may publish some categories separately or not at all.
Dates and distances move. The Manila Marathon ran in October, then August, then June, so its editions were 8 to 10 months apart. Several races added or dropped distances between editions: The archive holds only 10K results for EastWest Dream Run's 2025 Manila race and for Gemadept Run's 2024 and 2025 editions in Ho Chi Minh City, while both have a half marathon in 2026 [1], so part of their growth is a new distance.
One year is not a trend. Most of the 31 comparisons cover two editions, and a race can lose runners one year and win them back the next, as the swings at Isla del Fuego and Khun Dan show.
Using this when choosing a race
A growing race usually means a busier start, longer queues at packet pick-up and bag drop, and more company on the course. A shrinking one can mean a quieter, easier race day. Neither is better; it depends on what you want from the morning.
Some of the biggest fields in the archive have no latest edition to compare yet. Amazing Thailand Marathon Bangkok had 38,098 finishers across its marathon, half and 10K in 2025, the largest single race in our data. Borobudur Marathon had 10,357, Halong Bay Heritage Marathon 8,072 and the AIA Rock 'n' Roll Running Series Manila 5,860 [1]. Their next editions will show which way they are heading, and the page of each upcoming race on runsea.run shows its last edition's field.