Best ultra marathons in the UK (2026/27): races by distance and difficulty

Written by James Frost, founder of Flaming Phoenix. Updated October 2026.

Quick answer: the best UK ultra marathons for 2026/27 are Race to the Stones (100km on the Ridgeway, 10 to 11 July 2027) or Centurion's South Downs Way 50 for a first ultra, the Thames Path 100 or South Downs Way 100 for a first hundred, the Lakeland 100 for mountains, and the Winter Spine (268 miles, January) as the hardest race in Britain.

I make high calorie bars called Phoenix Bars, so most of my week is spent talking to runners who are training for the races on this page. That is the only angle here: Flaming Phoenix is not affiliated with any organiser, none of them has endorsed this guide, and every race is listed on its merits. I checked each date, distance, cut-off and fee on the organiser's own website or official entry page between 20 and 22 October 2026. Fees and dates move every year, so confirm on the organiser's site before you pay.

UK ultra marathons in 2027: next dates at a glance

This table lists the next edition of each race below, with the distance and entry fee published by the organiser (standard fee where several tiers exist; "full" means the organiser shows the race as sold out).

Dates for the Dragon's Back Race (every September), the Highland Fling, the Autumn 100 and Lakes in a Day had not been published for 2027 when I checked; the sections below give what the organisers do confirm.

What counts as an ultra marathon?

An ultra marathon is any race longer than the 42.195km marathon. In the UK the common steps are 50km (31 miles), 50 miles, 100km (62 miles) and 100 miles, with 200-mile and multi-day races above that. Read the cut-off before the distance: Centurion gives 13 hours for its 50-milers on the Downs, while the Lakeland 50 allows 24 hours for 50 mountain miles with about 3,100m of climbing, and the two races ask very different things of you.

The best first ultras: 50km and 50 miles

Race to the Stones and Race to the King

Race to the Stones (Threshold Trail Series) follows the Ridgeway from Lewknor to the stone circle at Avebury: 100km non-stop, the same 100km over two days with a basecamp, or one of two 50km days (Thames Valley on the Saturday, Ridgeline on the Sunday). The 100km has about 1,350m of ascent and a cut-off of more than 25 hours. The organiser counts over 20,000 finishes since 2013 and says over 40% of 2025 entrants planned to hike or mix hiking and running, so walking the climbs is normal here. The next edition is 10 to 11 July 2027; standard fees are £190 for the non-stop 100km, £180 for the two-day version (£270 with camping) and £95 for each 50km, with early-bird prices until 31 October 2026.

Race to the King, its sister race on 19 June 2027, starts and finishes at West Dean Gardens near Chichester. There are five options: the 30km Monarch's Loop (£65), a flat Coastal 50K round Chichester Harbour and Bosham, an undulating Castle 50K past Arundel Castle (both £85), an 80km and the full 100km (£180).

Centurion's 50s

Centurion Running sets a 13-hour limit on its South Downs, North Downs and Chiltern 50-milers, which makes them the obvious next step if you want to race against the clock on the Downs and in the Chilterns. The South Downs Way 50 runs from Worthing to Eastbourne on 10 April 2027 with 5,700ft (1,750m) of climb; the North Downs Way 50 goes from Farnham to Knockholt on 15 May 2027 with 5,600ft; the Chiltern Wonderland 50 is on 18 September 2027. Each costs £118. For a 50km, Centurion's Hundred Hills 50km at Stonor Park in the Chilterns (20 March 2027, about 1,200m of climb, 9 hours, £80) and the South Downs Way 50km (12 June 2027, 9 hours, £85) are the shorter options.

Lakeland 50, The Lap and Manchester to Liverpool

The Lakeland 50 starts at Dalemain near Ullswater and finishes in Coniston, sharing the weekend and the finish with the Lakeland 100 on 23 to 25 July 2027. It has about 3,100m of ascent and costs £190, but 2027 entries opened on 8 September 2026 and closed three days later, so set a reminder for next September. The Lap is a 47-mile, way-marked loop of Windermere with a 24-hour limit (8 May 2027, £150, already full). The Manchester to Liverpool Ultra 50 from GB Ultras (26 March 2027, full) is a flat, fast option if you live in the north-west.

The Ultra Challenge series

Ultra Challenge lists 24 events for 2027, most with 100km, 50km and 25km distances and covered rest stops about every 12.5km, with bigger stops roughly every 25km. The Jurassic Coast (15 to 16 May), London 2 Brighton (29 to 30 May), Lake District (5 to 6 June), Cotswold Way (12 to 13 June) and Thames Path (11 to 12 September, with a 100-mile option) are the best known. They suit anyone who wants a first ultra to feel like a long walk with friends and good food.

If this is your first ultra, pacing and eating go wrong far more often than fitness does. My guide to fuelling your first ultramarathon covers the eating, the ultramarathon training plan has 50km and 50-mile schedules, and for what to carry on a 50km trail race see my page on trail running food.

The best 100km races in the UK

For a first 100km, Race to the Stones and Race to the King (above) are the gentlest, with cut-offs of over 25 hours. Beyond those:

• Ultra X Scotland (1 to 2 May 2027, Inverness and Loch Ness): a 110km single stage with a 30-hour limit, or the same 110km split over two days with a camp, plus 100-mile, 60km, 50km, 25km and 16km races. Aid stations come about every 10km, and under-23s can enter free, subject to availability.
• Eryri by UTMB 100K (15 May 2027): 108km with 5,800m of climbing in Snowdonia. Ultra-Trail Snowdonia has been renamed Eryri by UTMB from 2027.
• Arc of Attrition 100K (23 January 2027): 82.7km and 2,708m along the South West Coast Path in Cornwall. It is already full; the 50K (49.4km) still had places when I checked.
• Devon 100km (17 April 2027): the second half of the Devon Coast to Coast, Chagford to Lynmouth across Exmoor, starting at 9pm with a 25-hour limit, £126.
• Beacons Way Ultra 100km (GB Ultras, 24 July 2027) in the Brecon Beacons, with a 100-mile version on the same day.

Past about 12 hours, gut training becomes a skill in its own right. My guide to gut training for ultras covers how to move from 40 to 90g of carbohydrate an hour without paying for it later.

The best 100-mile races in the UK

For a first hundred, choose between Centurion's Thames Path 100 (Richmond to Oxford, 1 May 2027, only 1,900ft of climb, 30 hours, £225) and the South Downs Way 100 (Matterley Bowl near Winchester to Eastbourne, 12 June 2027, 12,700ft, 30 hours, £225). Both need a 50-mile finish inside 15 hours as a qualifier. The North Downs Way 100 (Farnham to Ashford, 103 miles, 7 August 2027, £220) and the Autumn 100 (four 25-mile out-and-back spurs from Goring, 28 hours, 17 to 18 October in 2026, £220) complete Centurion's Grand Slam.

The Montane Lakeland 100 is Britain's best-known mountain hundred: a loop of the Lake District from Coniston with about 6,300m of ascent, £220, on 23 to 25 July 2027. Other hundreds worth knowing:

• Arc of Attrition 100M (22 January 2027): 173km and 5,507m on the Cornish coast path in midwinter.
• Eryri by UTMB 100M (14 May 2027): 163km and 9,200m, the most climbing of any 100-mile race on this page.
• Hardmoors 110 (22 May 2027, Helmsley to Filey on the Cleveland Way, 5,000m, 36 hours, from £200) and Hardmoors 160 (starting 21 May 2027, Scalby to Filey, 6,700m, 50 hours, from £251) from a series running since 2008.
• Devon Coast to Coast (17 April 2027): 112 miles non-stop from Wembury to Lynmouth over Dartmoor and Exmoor, 38 hours, £231, tracker included.
• The Wall (Rat Race, 12 June 2027): 70 miles from Carlisle Castle to Newcastle Quayside with a 26-hour limit and £245 entry. Not quite a hundred, but the organiser reports a completion rate of over 90%.
• West Highland Way Race (19 June 2027): 95 miles from Milngavie to Fort William, first run in 1985 and limited to 300 runners.

For the full list with cut-offs and qualifiers, see my guide to the best 100-mile ultramarathons in the UK. A hundred miles is a fuelling problem as much as a running one: the 100-mile ultramarathon nutrition guide and my page on drop bags and aid stations cover the hour-by-hour plan.

What is the hardest ultra marathon in the UK?

The Montane Winter Spine is the hardest ultra marathon in the UK: 268 miles of the Pennine Way from Edale, non-stop, in January, with 10,732m of ascent and a 156-hour limit. The 2027 race starts at 08:00 on 10 January 2027, has 150 places at £1,345, and asks for previous experience such as a mountain or moorland ultra over 100 miles or a Spine Challenger finish. The shorter Spine events on the same route (the Sprint and the Challengers, from 46 miles) start between 9 and 12 January. Andrew Tomlinson, who ran the Spine Sprint, wrote that Phoenix Bars "were my main source of solid food for the Spine Sprint. I just broke a bit off in small amounts continuously, right until the end." My Pennine Way food guide covers eating on that trail in winter.

The Dragon's Back Race covers 380km and 16,400m of ascent in six days from Conwy Castle to Cardiff Castle every September. Two-day versions now exist: Dragon's Fire from Conwy, new in 2026, and Dragon's Tail across Bannau Brycheiniog to Cardiff. I have a separate guide on what to eat on the Dragon's Back Race.

GB Ultras' Race Across Scotland is 215 miles in a single stage on the Southern Upland Way from Portpatrick to Cockburnspath, with a 100-hour limit; the 7 August 2027 race is already full. The Northern Traverse (3 to 7 April 2027) is 300km from St Bees to Robin Hood's Bay through the Lake District, the Yorkshire Dales and the North York Moors.

Best ultra marathons by nation

England

England has the deepest calendar, and most of it is above. Add Lakes in a Day (50 miles from Caldbeck to Cartmel with about 4,000m of ascent) for the best single-day tour of the Lake District, and Centurion's Wendover Woods 50 (14 November 2026, 10,000ft of climb in 50 miles, 15 hours, £115) for a very hilly 50 in the Chilterns.

Scotland: ultra marathons for 2026 and 2027

Scotland's big three are the West Highland Way Race, the Highland Fling (53 miles from Milngavie to Tyndrum with 2,300m of ascent; the 2026 race was held in late summer, on 29 August) and Ultra X Scotland. For the 2026 race the Fling asked for an ultra, a trail marathon or a road marathon under five hours finished after 1 January 2024. Still to come in 2026 is the Glen Ogle 33 from Killin (33 miles, 7 November 2026), a friendly first ultra. For 2027 there is the new Fife Pilgrim Way Ultra (90km from North Queensferry to St Andrews Cathedral, 1 May 2027), GB Ultras' Ultra Scotland 50 and 100 (5 June) and Glasgow to Edinburgh Ultra (57 miles, 9 October), and Race Across Scotland in August. Long gaps between towns make the West Highland Way its own fuelling puzzle, which I cover in the West Highland Way food guide.

Wales

Wales has Eryri by UTMB (14 to 16 May 2027, from 25km to 100 miles), the Dragon's Back Race and its two-day spin-offs, and a run of GB Ultras races: Ultra Wales 50 (19 June 2027), the Beacons Way Ultra 100km and 100 miles (24 July) and the Snowdon Ultra 50 and 100 (4 September). The Ultra Challenge Gower Peninsula event (17 to 18 July 2027) offers 100km, 75km and 50km on the coast.

Northern Ireland

Northern Ireland is missing from most lists, but 26 Extreme runs two scenic ultras: the Causeway Coast Ultra (64km from Portballintrae past the Giant's Causeway, held on 12 September in 2026) and the Mourne Way Ultra (about 84km with over 2,000m of climb from Kilbroney Park, held in June). Check the organiser's site for 2027 dates.

The best backyard ultras

The backyard format (a 6.7km loop every hour, on the hour, until one runner is left) now has its own UK calendar. I keep a separate guide to every UK backyard ultra and how the format works.

What changed in UK ultra running in 2026?

Ourea Events, which ran the Dragon's Back Race, the Cape Wrath Ultra and the Northern Traverse, ceased trading in March 2026 and went into administration. Ultra X bought the Dragon's Back Race and the Northern Traverse out of administration: the September 2026 Dragon's Back went ahead and Northern Traverse 2026 entries moved to 2027. The 2026 Cape Wrath Ultra was cancelled, and its trademark was bought by Ultra Endurance Series Ltd, the Spine organisers, who plan a non-stop race called The Wrath on the Cape Wrath Trail in 2027. Elsewhere, Ultra-Trail Snowdonia has become Eryri by UTMB, the Arc of Attrition now runs as Arc of Attrition by UTMB, and the Highland Fling was held in late August in 2026.

How do you get a place? Entries, ballots and qualifiers

Most UK ultras are first come, first served, but the popular ones fill fast. The Lakeland 50 and 100 opened 2027 entries at 09:00 on 8 September 2026 and closed them on 11 September. The West Highland Way Race runs a ballot (1 to 14 October 2026 for the 2027 race) and has new qualification criteria from 2027. Centurion's 100-milers need a 50-mile finish inside 15 hours, the Winter Spine needs a 100-mile mountain or moorland ultra or a Spine Challenger finish, and the Highland Fling needs a recent marathon or ultra. If a hard race in 2028 is the goal, the usual path is a 50-miler in spring 2027, a hundred in summer or autumn, and the qualifier race the following winter. If the Sahara appeals more than Britain, my Marathon des Sables training guide sets out a nine-month plan.

A month-by-month UK ultra calendar for 2027

The months below group the 2027 dates confirmed by organisers in October 2026.

How to fuel a UK ultra

Aid stations in Britain tend to be generous with crisps, cake and cola, but they are a poor plan on a wet night when your stomach has turned. Aim for the carbohydrate rate you have practised in training (60 to 90g an hour is the usual target for long races), carry some solid food you can eat while walking the climbs, and run your race through the ultra running calorie calculator to see the gap you will need to manage. My comparison of the best energy bars for ultra running explains why calories per gram decide what goes in your vest.

Phoenix Bars carry up to 557 calories in only 120g, with up to 66g of carbohydrate, and break easily into pieces for a vest pocket or a drop bag. Lepha McCartan used them at Ultra-Trail Snowdonia: "really tasty and easy to nibble on whilst climbing. I'd definitely use again and will take with me for Lakeland 50 miler in July". Try a pack of Phoenix Bars on long training runs before you rely on them on race day, and plan your recovery in the days after the race as carefully as the race itself.

Frequently asked questions

What is the easiest ultra marathon in the UK?

The 50km options at Race to the Stones and Race to the King and the Ultra Challenge 50km routes are the easiest UK ultras: cut-offs of 25 hours or more on the Threshold races, food stops every 12.5km or so on Ultra Challenge, and large walking fields. Race to the King's Coastal 50K is the flattest of them.

Can a normal person run an ultra marathon?

Yes. Race to the Stones has recorded over 20,000 finishes since 2013, and over 40% of its 2025 entrants planned to hike or mix hiking and running. If you can already run a half marathon, a 50km with a generous cut-off is a realistic target after a few months of steady training and practice eating on long runs.

How much does it cost to enter an ultra marathon in the UK?

From the fees in this guide: £80 to £118 for Centurion's 50km and 50-mile races, £95 for a Race to the Stones 50km, £150 to £245 for The Lap, the Lakeland 50 and The Wall, £220 to £231 for most 100-milers, and £1,345 for the Winter Spine. Charity places often cost less up front but come with a fundraising target.

What are the best 50 mile races in the UK?

Centurion's South Downs Way 50 (April), North Downs Way 50 (May) and Chiltern Wonderland 50 (September) for a timed race on good trails; the Lakeland 50 (July) for mountains; the Highland Fling (late August in 2026) in Scotland; and The Lap (May), at 47 miles round Windermere, for a mixed field of runners and walkers.

Which UK ultras need a qualifying race?

Centurion's 100-mile races ask for a 50-mile finish inside 15 hours. The Winter Spine asks for a 100-mile-plus mountain or moorland ultra or a Spine Challenger finish. The Highland Fling asks for a recent ultra or marathon, and the West Highland Way Race has new criteria from 2027. Most 50km and 50-mile races need no qualifier.

Sources: Centurion Running race pages; Race to the Stones and Race to the King (Threshold Trail Series); Montane Lakeland 50 and 100 entries; Montane Winter Spine; Arc of Attrition by UTMB; Eryri by UTMB; West Highland Way Race 2027 registration; Highland Fling; Ultra X Scotland; Dragon's Back Race news, April 2026; Cape Wrath Ultra; Northern Traverse; GB Ultras; Rat Race, The Wall; Devon Coast to Coast entries; Hardmoors; Ultra Challenge; The Lap entries; runABC (Fife Pilgrim Way, Glen Ogle 33); ITRA race listings (Causeway Coast, Mourne Way). All checked 20 to 22 October 2026.

Flaming Phoenix is not affiliated with, sponsored by or endorsed by any race organiser named on this page. Race names are used only to identify the events and belong to their owners.