The easiest 100K race for your first finish is the Tunnel Hill 100K in Vienna, Illinois: a flat rail trail, cool November weather and a 30-hour cutoff. Brazos Bend 100K in Texas is a close second, if you can handle the humidity.
I always tell athletes it's great to go through a progression: marathon, then 50K, then 50 miler or 100K, and then 100 miler. If you've run a marathon and/or a 50K, then a 100K is a great next race for you to run.
That's the path I took. I ran the Rocky Raccoon 100K in February 2022, before I ran my first 100-mile race at the Keys 100 that May, and before Brazos Bend that December.
A 100K is 62.1 miles, so you'll be out there most of the day and maybe into the night. Picking the right first one matters. I ranked eight of them below, from hardest to easiest, using four things: temperature, terrain, elevation gain and the cutoff.
8. Bandera 100K
- Where: Hill Country State Natural Area, Bandera, TX
- When: January 9, 2027
- Terrain: Two 50K loops of rocky, technical Hill Country trail
- Elevation gain: ~6,600 ft
- Avg high / low: ~60° / 42°
- Cutoff: 25 hours
A classic Texas 100K and a Western States qualifier. The course is two big loops through the Hill Country, with rocky climbs and loose limestone the whole way.
It's #8 because it has the most climbing and the most technical footing on this list. If this is your first 100K, make sure you've trained on rocks.
7. Javelina Jundred 100K
- Where: McDowell Mountain Regional Park, Fountain Hills, AZ
- When: Halloween weekend 2027 (date TBA; 2026 was October 31)
- Terrain: Three desert loops (one of 22.3 miles, two of 19.45), mostly smooth singletrack
- Elevation gain: ~3,200–4,000 ft (sources differ)
- Avg high / low: ~84° / 59°
- Cutoff: 29 hours
I haven't done this one, but it is a huge party. The atmosphere makes up for any difficulty that you face with a little bit more elevation or temperatures.
It's Halloween weekend, so a lot of runners race in costume. The heat is the real challenge. Average highs in the desert are in the mid-80s in October, so start your fueling and hydration early.
Sign up for Javelina Jundred →
6. Black Canyon 100K
- Where: Spring Valley to New River, AZ
- When: February 13, 2027
- Terrain: Point to point on the Black Canyon Trail, mostly downhill
- Elevation: ~5,200 ft gain, ~7,300 ft loss
- Avg high / low: ~65° / 44°
- Cutoff: 20 hours (17 hours to qualify for Western States)
A point-to-point course through the Sonoran Desert that loses more elevation than it gains. It's also a Western States Golden Ticket race, so the front of the field is fast.
It's #6 because of the cutoff. 20 hours is the tightest on this list. The downhill helps, but go out too fast and your quads will pay for it late.
5. Prairie Spirit 100K
- Where: Ottawa, KS
- When: April 3, 2027
- Terrain: Out and back from Ottawa to Welda on crushed limestone, with some asphalt through town
- Elevation gain: Minimal (gentle rail-trail grades)
- Avg high / low: ~60° / 38°
- Cutoff: 30 hours
A rails-to-trails course across the Kansas prairie, with aid stations about every 5 miles. The grades stay gentle, and the 30-hour cutoff gives you all the time you need.
It's harder than the races below because there's no loop. You don't come back past your crew and drop bags until you finish.
4. Rocky Raccoon 100K
- Where: Huntsville State Park, Huntsville, TX
- When: February 6, 2027
- Terrain: One 2-mile lap, then three 20-mile loops on soft, pine-needle trail, with roots
- Elevation gain: ~3,750 ft, in small rolling bits
- Avg high / low: 63° / 46°
- Cutoff: 31 hours
This was my first 100K. I ran it on February 5, 2022, and it was 23 degrees at the start. February in east Texas is usually mild, but it can surprise you, so pack layers.
You pass your drop bag and crew every 20 miles, and the climbing comes in small rollers, not mountains. Watch the roots, especially when you get tired. It's capped and sells out, so sign up early.
3. The Pistol 100K
- Where: Alcoa, TN
- When: March 13, 2027, 8 a.m. start
- Terrain: Six paved loops of 10.35 miles
- Elevation gain: ~1,200 ft
- Avg high / low: 61° / 39°
- Cutoff: 32 hours
Six paved loops just outside Knoxville. You come through the aid station every 10 miles, and the 32-hour cutoff is the most generous on this list.
Pavement is smooth, but it's hard on your legs over 62 miles. Get some long runs on the road before race day.
2. Brazos Bend 100K
- Where: Brazos Bend State Park, Needville, TX
- When: December 2027 (date TBA; 2026 is December 5)
- Terrain: Flat dirt and gravel loops
- Elevation gain: Under 100 ft
- Race-day high / low: ~71° / 55° on average (2021–2025), and humid
- Cutoff: 31 hours
I ran the Brazos Bend 100 in December 2022 on these same trails, and it's flat as a pancake.
I liked Brazos Bend, but it is very humid. When I ran it on December 3, 2022, it was 69 degrees with 100% humidity at the 6 a.m. start. Start your fueling and hydration early.
And yes, you'll probably see alligators sunning themselves next to the trail. They totally leave you alone.
1. Tunnel Hill 100K
- Where: Vienna, IL
- When: November 2027 (date TBA; 2026 is November 14)
- Terrain: Crushed-rock rail trail, out and back, never steeper than 2%
- Elevation gain: Flat
- Avg high / low: 55° / 37°
- Cutoff: 30 hours
It's #1 here for the same reason it's #1 on my easiest 50 milers and 100 milers for beginners lists: it's flat, and the weather is cool and predictable.
The Tunnel Hill State Trail is an old railroad line, so almost all of it is runnable. It's the coldest race on this list, so pack warm layers for the evening.
Summary: the easiest 100K races
| # | Race | Where | When | Elevation gain | Avg high / low | Cutoff |
|---|---|---|---|---|---|---|
| 8 | Bandera 100K | Bandera, TX | Jan 9, 2027 | ~6,600 ft | ~60° / 42° | 25 hr |
| 7 | Javelina Jundred 100K | Fountain Hills, AZ | Oct 2027 (TBA) | ~3,200–4,000 ft | ~84° / 59° | 29 hr |
| 6 | Black Canyon 100K | Spring Valley, AZ | Feb 13, 2027 | ~5,200 ft (7,300 ft down) | ~65° / 44° | 20 hr |
| 5 | Prairie Spirit 100K | Ottawa, KS | Apr 3, 2027 | Minimal | ~60° / 38° | 30 hr |
| 4 | Rocky Raccoon 100K | Huntsville, TX | Feb 6, 2027 | ~3,750 ft | 63° / 46° | 31 hr |
| 3 | The Pistol 100K | Alcoa, TN | Mar 13, 2027 | ~1,200 ft | 61° / 39° | 32 hr |
| 2 | Brazos Bend 100K | Needville, TX | Dec 2027 (TBA) | Under 100 ft | ~71° / 55°* | 31 hr |
| 1 | Tunnel Hill 100K | Vienna, IL | Nov 2027 (TBA) | Flat | 55° / 37° | 30 hr |
Dates marked TBA had not been announced as of November 2026. Temperatures are monthly average highs and lows for the nearest town, not official race figures, and are approximate. *Brazos Bend shows the average race-weekend high and low from 2021 to 2025.
Haven't run a 50K yet? Start with the 8 easiest ultramarathons for your first finish. Already thinking about the next step? Here are the easiest 50 mile races and 100 mile races for beginners.
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Common questions
What is the easiest 100K race?
The Tunnel Hill 100K in Vienna, Illinois. It's a flat rail trail that never gets steeper than 2%, with cool November weather and a 30-hour cutoff.
How long is a 100K race?
100 kilometers is 62.1 miles, about 2.4 marathons.
Should I run a 50K before a 100K?
It's a good idea. A good progression is marathon, then 50K, then 50 miler or 100K, and then 100 miler. If you've run a marathon and/or a 50K, a 100K is a great next race.
What should I look for in my first 100K?
Look at temperature, terrain, elevation gain and the cutoff. Mild weather, smooth trail, less climbing and a generous cutoff make a first 100K much more manageable. Loop courses help too, because you pass your crew and drop bags over and over.