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⏵ Course guide · Utah ultra

Salt Flats Endurance Runs Course Guide

The Salt Flats Endurance Runs are about as surreal as ultras get. You start on the Bonneville Speedway, the same salt where they set land-speed records, and run mile after dead-flat mile across a white crust toward mountain islands that float on the horizon. It is fast and the vert is low, but flat does not mean easy out here. I will walk you through the course first, then give you a pacing and fueling plan built for the salt, the sun, and the head game. There are free calculators along the way to dial in your own numbers.

⏵ At a glance

Salt Flats Endurance Runs quick facts

Date
Friday to Saturday, May 1 to 2, 2026 (typically the first weekend of May)
Location
Bonneville Salt Flats Speedway, West Desert near Wendover, Utah
Distances
100 Mile · 100K · 50 Mile · 50K (plus 5K and 10K fun runs)
Elevation gain
100M: about 5,700 ft · 50M: about 1,850 ft · 50K: very flat. Low vert for the distance
Start
All four ultra distances start together at 7:00 AM Friday on the Speedway
Cutoff
100M: 36 hr · 100K: about 23 hr · 50M: 14 hr · 50K: 10 hr, with intermittent aid cutoffs
Qualifier
Not currently listed as a Western States, Hardrock, or UTMB (Running Stones) qualifier

These facts come from the official race site and UltraSignup. Check the current date, cutoffs, and aid stations in the race-day details before you commit. Race logistics change year to year.

The course: where the Salt Flats is won and lost

Every distance starts together at 7 AM on the Bonneville Speedway and heads out across the salt. The first 13 miles or so are pure flat salt crust, then about three miles of mud flats, before the longer distances connect up with the islands. The 50K turns around out on the flats for a long, flat 50K, the 50 miler links two real climbs, and the 100 miler links four and even crosses briefly into Nevada before coming home.

The salt: fast, flat, and a mental grind

The opening stretch is the signature of this race. You are running on something like six feet of solid salt, usually firm and hard like hard-pack dirt, and it is genuinely fast. The trap is the monotony. There is no shade, no terrain to change up your stride, and the horizon barely moves, so the miles can mess with your head long before your legs are tired. Settle into a rhythm you can hold for hours, keep eating and drinking on a schedule, and do not let the early easy footing bait you into running harder than your goal.

One real variable to respect: if there has been any recent moisture the salt turns sticky and slow, and the mud-flat section near mile 13 can get gloppy. The surface you train your splits on in your head may not be the surface you get, so stay flexible and run by effort, not by the pace you assumed.

The islands: where the only real climbing lives

Once you reach the islands, the desert peaks that rise out of the salt like Silver Island, the course finally gets some shape. The 50 miler connects two significant climbs and the 100 miler connects four, on dirt jeep road, rocky 4x4 road, and fun ATV-trail descents. After hours of flat, your legs and your stride will feel weird on the first climb, so ease into it, hike the steep pitches, and treat the climbs as a welcome break rather than a place to hammer.

For the 100 milers this is also where the day gets long and lonely. You will be out here into the night and even cross into Nevada near where the Donner-Reed party left Utah, so plan your lights, your layers, and your low-point strategy for the back half. The climbs are not huge, but late in a 100 on tired flat-trashed legs, they feel a lot bigger than the numbers suggest.

Sun, wind, and the long gaps between aid

There is no cover anywhere out here, and a white salt surface throws the sun straight back up at you. Early May in the West Desert can start cold and windy at the dawn start and turn hot and blinding by midday, so sun sleeves, a hat, good sunglasses, and sunscreen are not optional, they are gear. The wind can also swing from a help to a slog depending on the day.

Aid stations are spaced out and most have no crew access (on the 50 miler, for instance, crew is only allowed at two of them, and drop bags start a few stations in), so you have to carry enough fluid and calories to get across the long flat gaps on your own. Pacers for the longer distances generally join later in the race at the crew-access aid stations, so know where you will see your people and where you will not.

Pacing strategy for a fast, flat salt ultra

With low vert and firm footing, the Salt Flats is one of the few ultras where a flat pace chart actually means something. The danger is not the climbs, it is going out too hot on the easy salt and cooking yourself in the sun before the islands.

Hold an honest, even pace on the salt

Because so much of this course is flat and fast, your flat-ground fitness translates pretty directly, which is rare for an ultra. Pick a pace you can truly hold for the whole distance and lock into it early, because the salt feels effortless for the first couple of hours and then quietly takes a toll. On the island climbs, switch to effort and hike the steep stuff so you do not spike your heart rate, then settle back into your flat rhythm on the descents and the run home. A grade-adjusted pace helps you keep that effort steady across the flats and the few climbs so you are not surging without realizing it.

Build a realistic finish prediction and work back to the cutoffs

Do not eyeball your Salt Flats finish off a road marathon and call it a day. The sun, the wind, the repetitive pounding, and the mental grind all add time even on a flat course, and the longer distances have intermittent aid cutoffs you have to stay ahead of. A finish prediction that accounts for the distance and the modest climbing gives you a realistic window, and then you can work backward into each aid-station cutoff so you always know how much buffer you actually have instead of guessing out on the salt.

⏵ Free tools to pace this course

  • Grade-adjusted pace calculator to keep your effort even across the flat salt and the island climbs instead of surging by accident.
  • Race-time calculator for a finish prediction on this distance and vert, so you can plan against the 36-hour, 14-hour, or 10-hour cutoffs.
  • Race-equivalent calculator to turn a recent race result into a Salt Flats goal you can actually hold across the salt.

Fueling strategy for the heat and the dry desert air

Depending on your distance you could be out here from five hours to well over a day, in dry desert air with full sun and no shade. That makes carbohydrate, sodium, and fluid every bit as important as fitness, maybe more.

Carbs: steady, trained, and easy to get down

Aim for around 60 to 90 grams of carbohydrate per hour, and only push the higher end if your gut is trained for it. The sun and the long monotony can kill your appetite, so keep your intake steady and simple instead of gambling on big late catch-up doses, especially deep in a 100 when nothing sounds good. Practice your exact race-day carb rate on long runs so 80-plus grams an hour feels routine and not like an experiment you are running for the first time at mile 60 on the salt.

Sodium and fluid: respect the dry air and the long gaps

The desert is deceptive: the air is so dry that your sweat evaporates fast and you may not feel how much fluid and salt you are losing until you are behind. Lean toward the high end on sodium, often around 500 to 700 milligrams per liter of fluid, and more if you are a heavy or salty sweater. Just as important, carry enough fluid to clear the long flat gaps between aid (many with no crew) rather than rationing to empty. Weigh yourself before and after a hot, dry long run to find your real sweat rate, then build the plan around your own number.

⏵ Build your fueling plan

Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and the Salt Flats sun with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.

⏵ Train for it with Summit Line

Get a race-day plan built around YOUR fitness, this exact Salt Flats course profile, and your projected splits. Summit Line reads your real training, builds a plan for the flat-fast pounding and the island climbs, and rehearses your fueling so race day is something you execute, not guess at.

Start free →Explore the demo

Salt Flats Endurance Runs FAQ

How hard is the Salt Flats Endurance Runs?

It is a different kind of hard than a mountain ultra. The vert is low (the 100 miler has only around 5,700 feet of gain and the 50K is one of the flattest trail courses around), so on paper it looks easy and fast. The catch is that you run mile after mile on dead-flat salt with no shade, no terrain changes to break up your stride, and full sun and wind, and that monotony plus the relentless pounding is what actually wears people down. Treat it as a fast course that asks for patience, sun management, and a strong head rather than big climbing legs.

How much climbing is in the Salt Flats Endurance Runs?

Not much, which is the whole point of this race. The 100 miler has roughly 5,700 feet of total gain over about 100.5 miles, and the 50 miler is around 1,850 feet over about 49.7 miles. The first stretch out of the start is flat salt and mud flats with essentially no vert, then the 50 mile and 100 mile routes connect a couple of real climbs (two for the 50, four for the 100) up into the desert islands like the Silver Island Mountains before dropping back to the flats. The 50K stays out on the salt and barely climbs at all.

How should I fuel for the Salt Flats Endurance Runs?

Plan for a hot, dry, salt-crust effort with long exposed gaps between aid. Most runners do well on roughly 60 to 90 grams of carbohydrate per hour, leaning to the higher end if your gut is trained, and the dry desert air plus salt glare cranks up your sweat and sodium loss even when it does not feel that hot. Lean toward the high end on sodium and carry enough fluid to clear the long flat stretches between aid instead of rationing to the next one. Run your numbers for your weight, goal time, and the forecast with the free ultra fueling calculator.

What are the cutoff times for the Salt Flats Endurance Runs?

The 100 miler gives you a generous 36 hours, which makes it friendly to a wide range of runners, the 100K is roughly 23 hours, the 50 miler is 14 hours, and the 50K is 10 hours. There are also intermittent cutoffs at aid stations along the way (for the 50 miler, for example, around 3:45 PM at the Jeep Trail aid, 5:45 PM at Rock Pile, and 7:30 PM at the Home Stretch aid), so you cannot bank all your buffer for the finish. Always confirm the exact intermediate cutoffs in the current race-day details before you start.

What is the terrain and weather like at the Salt Flats?

You start on the Bonneville Speedway, the same salt where land-speed records are set, and run about 13 miles of hard salt crust and roughly three miles of mud flats before reaching the islands. The salt is usually firm like hard-pack dirt, but if there has been any moisture it turns sticky and slow, and out at the islands you pick up dirt jeep roads, rocky 4x4 climbs, and ATV-trail descents. Early May in the West Desert can swing from cold and windy at the dawn start to hot, bright, and shadeless by midday, with zero cover and a white surface that throws sun straight back at you. Bring real sun protection and plan around the glare and the wind.

Is the Salt Flats Endurance Runs a good first ultra or first 100?

For the right runner, yes, and a lot of people pick it for exactly that reason. The low vert, the firm fast footing, and the very generous cutoffs (a full 36 hours for the 100) make it one of the more accessible big-distance ultras out there, and the 50K is a reasonable step up from a marathon. The honest flip side is the mental side: running flat, featureless salt for hours with no shade and no scenery to distract you is its own challenge, so prepare your head, your sun and hydration plan, and your feet for repetitive pounding as much as your fitness.

This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.