Upcoming 100Ks

Endurance Grid lists twenty-eight 100Ks across the US, from August 2026 to July 2027 across 17 states.

28
Races
17
States

The distance

What a 100K is

A 100K is a running race where athletes run 62.1 miles long (100 kilometers) for time.

100Ks are busiest in October and June, with the most in Connecticut, Colorado, Texas, and Indiana.

Frequently Asked Questions (FAQs)

How many 100K ultramarathons are there in the US?+
Endurance Grid's Race Calendar lists 28 upcoming 100K ultramarathons across 17 states.
How far is a 100K ultramarathon?+
A 100K is a running race where athletes run 62.1 miles long (100 kilometers) for time.
Which states have the most 100K ultramarathons?+
The states with the most 100K ultramarathons on Endurance Grid's Race Calendar are Connecticut, Colorado, Texas, Indiana, Wisconsin, and Pennsylvania.