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⏵ Course guide · Colorado ultra

Leadville Trail 100 Run Course Guide

The Leadville Trail 100 Run is the Race Across the Sky, one of the oldest and most storied 100 milers in the world, run out and back from downtown Leadville at the top of the Colorado Rockies. The vert is real but the altitude is the headline: the whole course sits above 9,200 feet, and you cross Hope Pass near 12,500 feet twice. I will walk you through the course, then give you pacing, fueling, crew, and pacer strategy built for thin air and a fast 30 hour clock, plus free tools to dial in your own numbers.

⏵ Quick facts

Leadville 100 at a glance

Date
Sat, August 22, 2026
Location
Leadville, Colorado (Sawatch Range, Rocky Mountains)
Distance
About 100 miles, out and back (officially near 99.7 mi)
Elevation gain
Roughly 15,500 ft of climb (about the same descent)
High / low point
Hope Pass near 12,500 to 12,600 ft · low near 9,200 ft
Start
4:00 AM, 6th and Harrison in downtown Leadville
Cutoff
30 hours (sub-25 earns the big buckle, sub-30 the small buckle)
Entry
Lottery or qualifier-race entry; no WS, Hardrock, or UTMB qualifier status listed

Note: the exact aid station cutoffs, crew access points, the mile pacers can join, and the entry rules get adjusted year to year, and entry is a low-odds lottery or a qualifier-race spot. So before you plan your race, confirm the date, route, cutoffs, and entry rules in the official Leadville Race Series athlete guide.

The course

Leadville is an out-and-back, starting on 6th and Harrison in downtown Leadville and running roughly 50 miles out to the turnaround at Winfield, then all the way back the same way. It is about 100 miles total on forest trail and mountain dirt road, much of it on the Colorado Trail, with roughly 15,500 feet of climbing. The whole thing sits above 9,200 feet, the high point is Hope Pass near 12,500 to 12,600 feet, and because it is out and back you climb that pass on the way out and again on the way home.

Start to Twin Lakes: the deceptively gentle first third

The gun goes at 4:00 AM in the dark and cold, and the opening stretch around Turquoise Lake to the Mayqueen aid station near mile 12 is some of the most runnable trail on the course. From there you climb over Sugarloaf and bomb down the Powerline descent toward the Outward Bound aid station near mile 24, then roll on toward Twin Lakes near mile 38. None of this is technical, and that is exactly the trap.

This is the part where people feel great and run too hard, banking time they think they will need. At 10,000-plus feet, every match you burn early costs you double later. Get to Twin Lakes calm, eating, and well within yourself, because the race has not even really started yet.

Hope Pass, out and back: the heart of the race

Out of Twin Lakes you ford a river or two and start the climb that defines Leadville: up and over Hope Pass at around 12,500 feet to the Winfield turnaround near mile 50. The climb is relentless and the air up high is genuinely thin, so almost everyone hikes it. Then you turn around at Winfield and do the whole thing in reverse, climbing back over Hope Pass a second time with 50-plus miles already in your legs.

That second, inbound Hope Pass crossing is where a lot of races end. You are tired, the altitude has been working on you all day, and you still have to grind back up to 12,500 feet and then make the tight Twin Lakes inbound cutoff on the far side. Respect this section. Save your legs and your stomach for it, because nothing else on the course is as hard.

Twin Lakes back to town: the long, high, night-time return

Once you are back through Twin Lakes inbound (and past that hard cutoff near 10:15 PM), you reverse the first third in the dark: the long climb back up the Colorado Trail, then the Powerline climb, which is a genuinely demoralizing grind late at night, and back down through Outward Bound and Mayqueen toward town. None of it is technical, but all of it is at altitude, in the cold, when you are wrecked.

The finish is a climb back up the Boulevard into Leadville to 6th and Harrison. The closing miles are runnable on paper, which rewards anyone who paced the altitude and saved something, and absolutely punishes anyone who emptied the tank early. A pacer and a clear plan for the night make a huge difference here.

Aid stations, crew, and pacers

There are roughly 11 aid stations along the out-and-back with water, food, and electrolyte drinks, and because of the course shape you pass most of them twice. The big crew-accessible points are places like Outward Bound, Twin Lakes, and the Winfield turnaround, and drop bags are allowed at designated stations. Plan your crew around the spots you will see them on the way out and again on the way back.

Pacers are allowed on the back half, generally from around the Winfield turnaround near halfway, so line up someone fresh to get you back over Hope Pass and through the long night home. The overall limit is 30 hours, with strict intermediate cutoffs (the Twin Lakes ones outbound and inbound are the ones that get people), so pull the current official athlete guide and build your plan backward from those times with real margin.

Pacing strategy for Leadville

A high-altitude, out-and-back 100 with two Hope Pass crossings rewards altitude discipline and patience way more than raw speed. Pace this course by effort and by breathing, and treat the runnable early miles as the real trap.

Pace the altitude, not your home splits

The single biggest mistake at Leadville is running the gentle early trail at your normal pace and banking time. At 10,000-plus feet your heart rate is higher at every speed, so what feels easy is costing you more than it would at home. Run the first 50 miles like you are trying to arrive at Winfield feeling fresh, hike the climbs early, and let the runnable sections come to you instead of forcing them.

Use our free grade-adjusted pace calculator to turn your flat-ground fitness into honest effort targets for the climbs and the long runnable stretches. Then you actually know whether you are pacing sustainably or spending legs and lungs you are going to want on the second Hope Pass climb.

Build a finish goal that respects the clock and the cutoffs

Do not guess your Leadville finish off a road or low-altitude time. The thin air, the two Hope Pass crossings, and the night all add real time, and the cutoffs are strict. A vert-aware finish prediction gives you a realistic window, and then you can work backward into the Twin Lakes outbound and inbound cutoffs so you know exactly how much buffer you need at each one.

Use our race time calculator for that finish window, then check it against the 30 hour limit and the big-buckle 25 hour mark so your plan has margin baked in, not just hope. The runners who make the tight inbound cutoffs are almost always the ones who built their whole race around them.

Plan the second half and the night

Leadville is really two races: get to Winfield in one piece, then survive the trip home. The second Hope Pass climb, the Powerline grind in the dark, and the long cold night are where well-trained runners fall apart, usually because they spent too much early. Pick up your pacer with a clear plan, keep eating through the night even when you do not want to, and expect your pace to be slow and your job to be simply to keep moving.

If you want to reality-check your goal time against a recent race before you commit, our race equivalent calculator helps you see how your current fitness lines up with a 100 mile mountain effort at altitude like this one.

Fueling strategy for Leadville

At altitude, fueling and hydration get harder and matter more. The thin air slows your gut and dries you out, so build your plan around keeping calories and fluid going down when your stomach would rather quit.

Carbs: steady, easy, and trained for thin air

Target roughly 60 to 90 grams of carbohydrate per hour, but be honest that the altitude makes the top of that range hard for a lot of people. A hot, high, sloshing stomach takes less, so keep your intake steady and easy to swallow, lean on things you know go down when your gut is grumpy, and do not wait until you feel sick to eat. Use a glucose-plus-fructose blend so you can absorb more than a single sugar allows, and rehearse your exact hourly number on long runs so it is automatic on race day.

Keep eating through the night and the second Hope Pass climb, when your appetite is gone but your engine still needs fuel. The runners who blow up late at Leadville are very often the ones who quietly stopped eating somewhere around Winfield.

Hydration and sodium: built for altitude

Altitude dehydrates you faster than you expect, so stay ahead of your fluid the whole way instead of catching up at aid stations. Bias your sodium toward the middle-to-high end, often around 400 to 700 mg per liter of fluid, and more if you are a salty or heavy sweater. Cramping, a sloshy stomach, and that wrung-out hollow feeling late in the race are usually fluid and sodium problems, not fitness problems.

Get a plan of your own with our free ultra fueling calculator. Put in your weight, your goal time, and the conditions, and it gives you a carb, sodium, fluid, and caffeine number per hour built for the Leadville duration. Then go test it on long runs, at elevation if you can possibly get there.

Train for the conditions

Leadville asks for a lot at once: altitude, 100 mile endurance, the vert of two Hope Pass crossings, and the night. These guides go deep on the parts that decide your day.

⏵ Free calculators for this race

Run your Leadville numbers with our free, no-signup tools, then let Summit Line tie them all together with your real fitness and this exact course.

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⏵ Train for Leadville

Get a race-day plan built around YOUR fitness, this exact course profile, and your projected splits. Summit Line reads your actual training, builds a fueling and pacing plan around the Leadville altitude and the two Hope Pass crossings, and tracks how your gut and legs handle the load, so race day is rehearsed instead of guessed.

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Leadville Trail 100 Run FAQ

How hard is the Leadville Trail 100 Run?

Leadville is hard in a way the elevation profile alone does not show you. It is about 100 miles with roughly 15,500 feet of climbing, which is real but not the most vert in the 100 mile world, and the whole course sits above 9,200 feet with a low point higher than most races ever climb to. The altitude is the headline. You start in the dark at 4:00 AM, cross Hope Pass at around 12,500 feet twice, and try to do it all on thin air that makes every climb feel harder and your stomach turn on you. Add the famously tight Twin Lakes cutoffs and a 30 hour clock and you have one of the most storied and most failed 100s anywhere. Plenty of fit runners do not finish, and the ones who do tend to respect the altitude from the gun.

How much climbing is in the Leadville 100, and how high does it get?

The course climbs roughly 15,500 feet across the out-and-back, and because it finishes where it starts you descend about the same. The defining feature is Hope Pass, the high point near 12,500 to 12,600 feet, which you climb on the way out to Winfield and again on the way back, so you summit it twice. The low point is still around 9,200 feet near the Twin Lakes area, which means you never actually drop to anything most people would call low. The biggest single efforts are the two Hope Pass crossings, with the inbound climb back over the pass late in the race being the one that breaks a lot of days.

What are the Leadville 100 cutoffs?

The overall limit is 30 hours from the 4:00 AM start, so you have to finish by 10:00 AM the next morning. There are also intermediate cutoffs at the aid stations, and the ones at Twin Lakes are notorious: you generally have to be through Twin Lakes outbound by early afternoon (around 1:30 PM near mile 38) and back through Twin Lakes inbound by late evening (around 10:15 PM near mile 62). Those inbound cutoffs come right after the second Hope Pass climb, so a lot of runners are racing the clock there with almost no margin. Finish under 25 hours and you earn the big silver buckle, under 30 hours and you get the smaller one. Confirm the exact current-year aid station cutoffs in the official athlete guide before you build your plan.

How do I deal with the altitude at Leadville?

The altitude is the thing that decides most Leadville races, so treat it as the main event, not a footnote. The whole course is above 9,200 feet and tops out near 12,500 at Hope Pass, which means less oxygen, a higher heart rate at any pace, and a gut that is more likely to rebel. If you live near sea level, the best options are to arrive either a couple of days before the race (before the worst of acclimatization sets in) or two to three weeks early to actually adapt, and to do altitude or simulated-altitude prep in the build-up. On race day, pace everything by effort and breathing rather than your home splits, hike the climbs early so you are not redlining in thin air, and keep drinking, because altitude dehydrates you faster than you think.

Can I have a crew and a pacer at Leadville?

Yes, and at a race this hard you want both. There are a handful of crew-accessible aid stations along the out-and-back, with the big ones being places like Outward Bound, Twin Lakes, and the Winfield turnaround, and you hit most aid stations twice because of the course shape. Pacers are allowed on the back half of the race, generally from around the Winfield turnaround near halfway, so plan a fresh pair of legs and a clear head to get you back over Hope Pass and through the night. Drop bags are allowed at designated aid stations too. Confirm the current crew-access points and the exact mile pacers can join in this year’s official athlete guide, since the race adjusts these details.

How should I fuel for the Leadville 100?

You are fueling a long day and night at serious altitude, and the altitude is what makes Leadville fueling tricky. Most runners target 60 to 90 grams of carbohydrate per hour, but thin air slows your stomach down, so many people land toward the lower-to-middle of that range and have to work to keep eating at all. Keep your calories steady and easy to get down, favor things that go down when your gut is unhappy, and do not wait until you feel bad to eat. Hydration matters more than usual because altitude dries you out, so stay on top of fluid and electrolytes the whole way. Practice your exact hourly plan on long runs, ideally at elevation if you can get it, and our free ultra fueling calculator will turn your weight and goal time into a carb, sodium, and fluid target per hour.

This guide is for planning and training, and it reflects publicly available information about the Leadville Trail 100 Run. Race details, including the date, course, aid stations, cutoffs, crew and pacer rules, and entry and lottery rules, can change year to year. So always confirm the current specifics in the official Leadville Race Series athlete guide before you train or travel.