100 Mile Ultra Marathons UK

There’s no magic formula, but a solid base of experience is key. Most race organisers will require you to have completed a 50 mile ultra marathon (or sometimes longer) within the last 12-18 months. Beyond race results, it’s about your personal journey. Are you comfortable running through the night? Have you tested your nutrition and gear on long training runs? Are you mentally prepared for the inevitable highs and lows? If you’ve got a few 50-milers under your belt and the hunger for a bigger challenge, you’re likely ready to start training.

Think about what plays to your strengths and what kind of experience you want. Consider these three things:

• Terrain: Do you love technical, hilly routes, or would you prefer a flatter, faster course to build confidence? Elevation gain is a huge factor in a race's difficulty.
• Navigation: Are you a skilled navigator or would you prefer a well-marked course? Many UK 100-milers require you to use a GPX file on a watch or device.
• Logistics: A lapped course can be simpler for a first attempt as you pass your drop bag and crew multiple times. A point-to-point race is a grander adventure but requires more planning.

Read the race descriptions, check out a few race reports online and find one that excites you!

Most ultra marathons have a mandatory kit list which is a set of specific items you must carry with you at all times during the race. In the UK, this is a crucial safety measure. Our weather is famously unpredictable, and a full waterproof body cover, hat, gloves, headtorch and emergency foil blanket can be lifesaving if you get into trouble. Race organisers perform kit checks and you will be disqualified for not carrying the required items. Always check the official race website for the most up-to-date kit list.

A crew is your personal support team (usually friends or family) who meet you at designated checkpoints to help with nutrition, gear changes and moral support. A drop bag is a bag you prepare yourself and give to the race organisers at the start. They transport it to a specific checkpoint (often around the halfway mark), allowing you to access spare kit, food, and other supplies without needing a crew. Most races allow drop bags but crew access can be limited.

GB Ultra Runner is a race directory designed to help you discover great ultras across the UK. To enter an event, you need to click the red View Race Website button on the listing, which will take you directly to the official race website. There you'll find all the details about the entry process, prices and dates.

I do my best to keep all information, such as dates and elevation, as accurate as possible. However, race organisers can and do make changes. Your single source of truth should always be the official race website. Please double-check all details with the organiser before making any plans or entering a race.