Triathlon events UK 2027: calendar with official dates

This calendar lists triathlon events in the UK for 2027 that have a date published on the organiser's own website. We checked every date on 6 October 2026. The 2027 season on this list runs from the Outlaw Nottingham Half on 23 May to the Hever Castle Triathlon on 25–26 September, with Blenheim, Windsor and London in between.

Every 2027 date below comes from the organiser's official page. Where an organiser has not yet published a 2027 date, we say so and leave it out of the table. We do not work out dates from previous years, because organisers move races for tides, venue bookings and other reasons. Dates can still change after publication, so confirm on the official site before you book travel or accommodation.

UK triathlon events 2027 by month

The tables give the event, the organiser, the venue, the distances as the organiser states them, the 2027 date and, where an official source confirms it, the date of the 2026 edition, which has already taken place. A dash means we could not confirm the 2026 date on an official page.

May 2027

The Outlaw Half uses a time-trial swim start, where swimmers enter the water in small groups. The organiser lists a Sprint, an Aquabike and Future Outlaw races at the same venue. Individual entrants must be 18 by 31 December 2027. For relays, the swim and bike legs are open from 17 and the run leg from 18.

June 2027

At Blenheim the bike legs use closed-road sections through the palace grounds, and there is a youth category on the Sunday SuperSprint (the official page does not give the age). The 2026 pro race was a stage of British Triathlon's Super Series.

At Windsor the swim goes downstream and then upstream on the Thames, the bike is on open roads where the Highway Code applies, and the run goes into Windsor Great Park along the Long Walk. Minimum ages are 15 for the Sprint and 17 for the Standard. The race was first held in 1991. One detail to check: the official description gives a 20 km sprint bike, while the course text says 22 km.

Bolton Council reported that more than 10,000 athletes took part across the 2026 race weekend, which also included a Night Run and IRONKIDS races.

July 2027

August 2027

This is the event many people still call the London Triathlon. Our London T100 Triathlon guide covers the dock swim and how to prepare.

September 2027

The Castle Race Series also lists 2027 dates for its other events: Lough Cutra on 29–30 May, Chateau de Chantilly on 12–13 June, Cholmondeley in late June (check the exact days on the series website) and Belvoir on 17–18 July. Distances and venue details for each are on the series website. If you are new to middle distance, our guide to half ironman races in the UK explains what the 70.3 and Half distances involve.

What "date not published (checked 6 October 2026)" means

When you see this note, it means we opened the organiser's official website on 6 October 2026 and it did not show a 2027 date. It is a record of what the official page said on that day. It does not mean the race is cancelled or moving.

Organisers announce dates at different times of year, so a race without a date today may publish one soon. We leave a race out of the 2027 tables until its date is on the organiser's own page, and we do not use dates from listing sites, social media posts or news reports for the 2027 column.

Events whose 2027 date is not yet published

These races ran in 2026 or are regular fixtures, but no 2027 date was on the official page when we checked:

• Thames Turbo Sprint Triathlon (Thames Turbo Triathlon Club): a club-run race at Hampton Open Air Pool, Hampton TW12 2ST, with a 432 m pool swim, 21 km bike and 5 km run in Bushy Park. The 2026 race took place on Monday 4 May 2026. The club describes it as ideal for a first triathlon. The club also ran a Junior Aquathlon on 7 June 2026 and a Women's Aquathlon on 20 September 2026. 2027 date not published (checked 6 October 2026).
• The Swashbuckler Triathlon (Challenging Events Ltd): normally held at Buckler's Hard, Beaulieu, in the New Forest. In 2026 it ran as "Swashbuckler On Tour" at Ellingham Water Ski Lake, Moyles Court School, Ringwood, on Sunday 5 July 2026, because the organiser said limited high tides made a Buckler's Hard date impossible. The 2026 options included a Standard (1.1 km / 33 km / 10 km), a Sprint (400 m / 33 km / 5 km), an Aquabike and a Duathlon. 2027 date not published (checked 6 October 2026).
• Dorney Lake triathlons (Dorney Lake, Court Lane, Windsor SL4 6QP): several organisers have used this rowing lake. The venue's own site had no triathlon listing, and RunThrough's official Dorney Lake page listed only duathlons, the next being the Dorney Lake Duathlon on 8 November 2026. 2027 triathlon date not published (checked 6 October 2026).
• British Triathlon national and age-group championships 2027: we could not confirm 2027 dates on an official page. Check British Triathlon's championships pages.

If you prefer run-bike-run or swim-run races, our duathlon and aquathlon guide explains the formats.

Where to find more UK triathlon events

This calendar covers a selection of well-known races with confirmed dates. There are many more triathlons in the UK each year, including small local and club races. Two places to look:

1. British Triathlon event search. British Triathlon runs an event search on its website at britishtriathlon.org/events, with individual event pages. It is also where you buy a Race Pass if your entry does not include one.
2. Organisers' own websites. Most organisers run a series of races and publish all their dates in one place. The organisers on this page (Outlaw Triathlon, Supertri, RunThrough, IRONMAN, T100 Triathlon, Castle Race Series, Challenging Events and Thames Turbo Triathlon Club) are a good starting point. Sign up for their newsletters if you want to hear when dates are released.

Listing and aggregator sites can be useful for ideas, but they may carry out-of-date or estimated dates. Always confirm on the organiser's own page before you pay.

Before you enter

A few checks save trouble later:

• Minimum age. British Triathlon sets minimum ages by distance, and organisers state their own in the entry conditions, such as 15 for the Royal Windsor Sprint and 18 for the Outlaw Half.
• Licence. For British Triathlon-permitted events you need a Race Pass or a Core or Ultimate membership. Our guide to British Triathlon rules explains both, along with wetsuit temperatures and drafting.
• Swim type. Pool, lake, river, dock or sea swims feel very different. Practise in similar conditions.
• Bike roads. Some courses use closed roads, others open roads where the Highway Code applies. The athlete information says which.

Frequently asked questions