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London's longest run. Congratulations to all our amazing runners and volunteers in 2025's London 100!
London 100 is Central London's urban-ultra and ONLY 100km run. Entries to London 100 (2025) are now CLOSED. We can't wait to be back with Central London's only 100KM event - we're in it for the long run!
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London 100 is an urban-ultra. An ultramarathon starting and finishing from our run HQ in central London. A route showcasing the very best that the capital has to offer and run route taking in 100+ of London's top landmarks.
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London 100 Challenges:
London 100 - 100km ultramarathon and ultimate bragging rights
London 50 - 50km ultramarathon
London 25 - 25km Central London run​
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LONDON 100
INFO
London 100 is Central London's ultramarathon. With 3 challenge distances (100km, 50km, and 25km), the event has distances for experienced ultramarathoners, and for those stepping up from marathons or half marathons.
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From a superb indoor Central London race HQ, four 25km routes explore north, south, east and west of the capital. Experience areas of London you never knew existed, discover the capital's hidden trails and enjoy the famous sights and landmarks of one of the world's greatest cities - all in one long run.
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START TIMES:
100km start times (from) 7am
50km start times (from) 9am
25km start times (from) 9am
Maximum time permitted to complete the 100km - 17 hours
Event closes 12am
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URBAN-ULTRA:
As an urban-ultra, we are accessible and inclusive. As many in the ultramarathon community will testify, entering, getting to and home from an ultramarathon, with accommodation and food costs can end up being a '£500 weekend'. Central London is highly accessible. The event is designed to allow easy access to and home from the event.
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MEDALS / TOP 100:
Run your way onto our list of London's top runners. Finish before midnight to receive your coveted London 100 medal. Finish in the Top 100 and see your name included in our list of London's running royalty.
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CHECKPOINTS:
Route checkpoints are positioned at the start and middle of each 25km route section. Well-stocked and ready to give you that all important boost of energy. Water, snacks and fruit available.
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PLAN YOUR RUN
Run for Charity
Training Program
Travel and Accommodation
At L100 Ultra, we believe in giving back to the community. Join us in supporting our partner charities by running for a cause. It's a great opportunity to make a difference while achieving your personal goals
Preparing for an ultra-marathon requires planning and training. We will help you prepare, point you in the right direction for support and advice, and provide some great blogs to help you learn more about the ultra experience.
By hosting our event in the Capital, we are hoping to provide an inclusive and accessible ultramarathon. L100 will be easy to get to and home from for many. And easy for your supporters to reach multiple parts of the course.
THE TEAM
