London Marathon Events confirmed on Friday, June 19, 2026, that the 2027 London Marathon will expand into a historic two-day event on Saturday, April 24, and Sunday, April 25, 2027.
The unprecedented move, called "the Double," will allow a record-breaking 100,000 participants to run the iconic course from Greenwich to Westminster.
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This nearly doubles the 60,512 runners who started the 2026 race.
Organizers designed the one-off format change to manage overwhelming demand, following a record 1.33 million applicants in the ballot for the upcoming event.
New Structure for Elite and Mass Participation
Under the new structure, elite women, elite female para-athletes, championship, and "good for age" women will compete on one day alongside a mixed mass participation field of nearly 50,000 runners.
The alternate day will feature elite men, elite male para-athletes, championship, and "good for age" men headlining a second mass participation event.
Participants cannot run on both days.
To support local communities, every London borough along the route will receive extra guaranteed entries, and every London school will receive two guaranteed places for staff members.
The expansion is projected to generate a £400 million social and economic benefit for the UK economy and smash fundraising records, following a 2026 event that has raised more than £90 million so far.
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The plan secured critical backing from the London mayor's office after initial institutional resistance, as Transport for London voiced concerns about closing the capital across two consecutive days.
