Explainers
What is fastpacking?
It's trail running crossed with ultralight backpacking: a multi-day route covered with a pack you can run in. What you give up to move that light, and whether it's for you.
Fastpacking is what happens when a trail runner decides not to turn around at the top. You take a route that would be a two or three day backpacking trip, carry a pack small enough to run in, and cover it in less time. You hike the climbs, run the descents, and sleep out somewhere in the middle.
Definitions vary a little, but they all land in the same place: trail running and ultralight backpacking, overlapping. Nobody governs it. There's no minimum pace and no distance that makes it official, so if you carried overnight gear and moved faster than you would have with a full pack, you were fastpacking.
The short version
- It's multi-day hiking with a pack light enough to run in, usually 20 to 35 liters. Reviewers who test them put the sweet spot at 28 to 30 for a night or two out.
- It isn't a race, and it isn't a record attempt either. Most people who call it fastpacking hike faster and farther and run the downhills. Very few are running all day.
- The word is younger than the sport. Jim Knight coined it in 1988, after he and Bryce Thatcher crossed close to 100 miles of the Wind River Range in 38 hours.
- You trade comfort and margin for distance. A smaller pack carries less food and less insulation, and it leaves you nothing spare on a day that goes wrong.
- Fitness is the entry requirement. If you can't already cover the distance without a pack, a lighter pack won't fix that.
The numbers behind light and fast
- 20–35 L
- Typical fastpack volume
- Under 10 lb
- Ultralight base weight
- 2.5–3.5 mph
- A realistic moving pace
- 1988
- When the word was coined
Treeline Review's testers put the sweet spot at 28–30 L for a night or two
Base weight is your loaded pack minus food, water and fuel
Hold that for 10 to 12 hours and you've covered 25 to 40 miles
Jim Knight, writing in UltraRunning after 38 hours in the Wind Rivers
Fastpacking vs backpacking vs trail running
They overlap enough that people argue about the labels. Mostly it comes down to how much you carry, and how much slack you have left when something goes sideways.
| What changes | Fastpacking | Backpacking | Trail running |
|---|---|---|---|
| Time out | One to four days | Any length, at whatever pace suits | Hours. Home the same day. |
| Pack size | 20–35 L | 50–65 L suits most backpackers | 3–12 L vest, or nothing at all |
| Base weight | Ultralight territory, under about 10 lb | Under 20 lb is lightweight, over 25 traditional. Both fine. | Barely a concept. Water and snacks. |
| Footwear | Trail running shoes | Boots or trail shoes, your call | Trail running shoes |
| Shelter | Tarp, bivy, or a tent pitched on your poles | Freestanding tent, often a two-person | None |
| Pace | Hike the climbs, jog the flats, run the descents | Walk, and stop whenever you feel like it | Run, mostly |
| Margin when it goes wrong | Thin. You're carrying very little spare. | Wide. The extra layer is already in the pack. | Wide. The car is a couple of hours away. |
Volumes depend on who you ask. Treeline Review counts anything from 20 to 35 liters as a fastpack; Adventure Alan recommends 30 to 50 for multi-day trips. Both are right, and which one applies to you comes down to how many days of food you have to fit.
What actually changes in the pack
The number the sport cares about is base weight: your loaded pack minus the things you consume, so no food, water or fuel. It's the only figure that stays still while you walk, which is why everyone compares it. By the convention most gear lists use, under about 10 pounds is ultralight, under 20 is lightweight, and above 25 is ordinary backpacking that nobody should apologize for.
Almost all of the saving comes from three items. The pack loses its frame and picks up running-vest shoulder straps, so it sits against your back instead of swinging behind it. The tent becomes a tarp, a bivy, or a single-wall shelter that pitches on your trekking poles instead of carrying its own, which means something you were bringing anyway now does two jobs. And the sleeping bag becomes a quilt. Swap those three and you've done most of the work. Everything after that is ounces.
Footwear goes the same way. Fastpackers wear trail running shoes rather than boots, because a pack you can run in doesn't help much if your feet can't. Call it a strong preference rather than a rule, since plenty of people want more shoe than that. It's still what nearly everyone in the sport ends up wearing.
What I wouldn't do is buy any of it first. Consumables are what actually decide your pack size, and you won't know what you eat and drink on a long fast day until you've had one. Start with the pack you own, see what you reach for, and let the kit follow.
Who fastpacking suits, and who it doesn't
This is the part most explainers skip. Fastpacking is great, and it isn't for everyone, and the line between those two isn't toughness. It's what you want out of a weekend.
It probably suits you if
- You already run long on trail without a pack, so the distance isn't the scary part.
- You'd rather see more of a route than spend the evening sitting at camp.
- Your time off comes in twos and threes, and the trip you want takes four days at walking pace.
- You can navigate, read weather, and turn around without sulking about it.
- You already own most of a light kit and you're curious what happens if you run in it.
Give it a season if
- This would be your first night out. Learn to camp before you learn to camp fast.
- Your longest trail run is under a couple of hours. Build that first; the pack is the easy half.
- Camp is the bit you like: the stove, the book, the second coffee. Fastpacking deletes all of it.
- You'd be going somewhere remote, and solo, for the first time.
- Trying it would mean buying a whole kit up front just to find out.
How to try fastpacking without a miserable first trip
None of this needs a purchase. The point is to find out whether you like moving this way before you spend anything making it lighter.
- 01
Run with the pack you already own
Load whatever daypack is in your closet with roughly what an overnight would weigh, and take it out for an hour on trail. Ten minutes of running tells you more about whether a pack bounces than any amount of reading.
If it swings, that's a harness problem, not a weight problem.
- 02
Pick a route you've already walked
A first fastpack is a bad place to also be navigating for the first time. Take something you know the shape of, so the only new variable is the pace.
- 03
Make it one night, not three
One night needs about a third of the food and none of the resupply planning, and it still teaches you the things you came to learn: how you sleep, how you eat, how the second morning feels.
- 04
Pack it, weigh it, then carry it up a hill
Weigh the whole thing before you go. The number matters less than your reaction to it, and a loaded climb close to home tells you honestly whether the route you picked is the right size.
- 05
Build the distance before you shrink the kit
Cutting gear is the fun part and the small part. Almost everyone who has a bad first trip had a fitness gap, not a gear gap, and no pack is light enough to close that.
Words you will hit straight away
- Base weight
- Your loaded pack minus consumables — no food, water or fuel. It's the number people compare, because it's the only one that doesn't shrink as you eat.
- Ultralight
- A base weight under about 10 pounds. Lightweight is under 20. Traditional backpacking sits above about 25, and there's nothing wrong with being there.
- Fastpack
- A pack in roughly the 20 to 35 liter range, built with running-vest shoulder straps instead of conventional ones, so it hugs your back rather than bouncing off it.
- FKT
- Fastest Known Time — the recorded best time on an established route. Fastpacking and FKT attempts share the skills, but almost no fastpacking trip is a record attempt.
- Unsupported
- An FKT style: you carry everything from start to finish and take nothing but water from natural sources along the way.
- Self-supported
- An FKT style: you may use any help that would be equally available to anyone else — a shop, a motel, a cache you laid yourself — but nothing arranged just for you.
- Supported
- An FKT style: a crew can meet you, feed you and carry your things, as long as you move entirely under your own power.
- Power hiking
- Walking uphill deliberately hard, hands on your thighs or driving through poles. On a loaded climb it's usually as fast as running, and much cheaper.
- Cowboy camping
- Sleeping out with no shelter at all. The lightest option there is, and the one the weather punishes hardest.
Common fastpacking questions
Do I have to actually run to call it fastpacking?
No. Most people who say they're fastpacking aren't running all day. They're hiking faster and farther and running the downhills. Running every mile of a 30-plus mile day while carrying camping gear is a small minority of the sport, and nobody checks.
How far is a fastpacking day?
Far enough that the number isn't the useful part. A realistic moving pace on runnable ground is around 2.5 to 3.5 mph, and people hold that for 10 to 12 hours, which works out anywhere from 25 to 40 miles. Terrain moves that figure more than fitness does. For scale, the Park Service rates Shenandoah's trails at 1.2 to 1.5 mph for ordinary hiking, so a rocky, steep route can halve your day.
Is fastpacking the same as an FKT attempt?
No. An FKT is a timed record on a defined route, run under published rules about support and verification, and timed on elapsed rather than moving time. Fastpacking is just a way of traveling. The two share the skills and almost never the intent.
Do I need a special pack to start?
Not for a first trip. A 20 to 30 liter pack you already own will tell you whether you enjoy moving this way. What a purpose-built fastpack buys you is the running-vest harness that stops the load swinging, and that's worth having once you know you want it.
Do permits still apply if I'm only out for one night?
Yes. Wilderness overnight quotas count the night, not the pace. Desolation Wilderness allocates its overnight quota by the number of people entering each day and their first night's destination zone; Yosemite reserves its wilderness permits by entry trailhead and date of entry. Neither has a column for how fast you're moving, so check with the managing agency before you plan around a fast schedule.
Does moving fast change the Leave No Trace rules?
Not at all. The seven principles apply at every pace, and the first one — plan ahead and prepare — matters more here than almost anywhere, because you're carrying less of the equipment that normally covers for a bad plan.
One piece of gear this genuinely leans on
There's no fastpacking gear guide on this site, and I'm not going to fake one. Trekking poles are the honest exception: on a light kit they do two jobs, because most ultralight shelters pitch on the poles you were already carrying instead of bringing their own.
Sources
Facts on this page were checked against these. Conditions, fees and rules change — check the official page before you go.
- FKT Guidelines — Fastest Known Time · checked August 2, 2026
- Hypothermia — Rocky Mountain National Park, National Park Service · checked August 2, 2026
- Stay Safe in the Extreme Cold — National Weather Service, Duluth · checked August 2, 2026
- Desolation Wilderness Permits — Eldorado National Forest, USDA Forest Service · checked August 2, 2026
- Wilderness Permits — Yosemite National Park, National Park Service · checked August 2, 2026
- How to Determine Hiking Difficulty — Shenandoah National Park, National Park Service · checked August 2, 2026
- Leave No Trace Skills & Ethics Guide — Leave No Trace Center for Outdoor Ethics · checked August 2, 2026
- Leave No Trace Seven Principles — National Park Service · checked August 2, 2026
- The Evolution of Fastpacking — Backpacking Light · checked August 2, 2026
- Founded in Fast and Light: Interview With UltrAspire's Bryce Thatcher — GearJunkie · checked August 2, 2026
- 8 Best Fastpacks of 2026 (Tested and Reviewed) — Treeline Review · checked August 2, 2026
- How to Choose a Backpacking Backpack — Treeline Review · checked August 2, 2026
- 8 Best Running Hydration Vests of 2026 (Field-Tested) — Treeline Review · checked August 2, 2026
- Best Fastpacking Backpack For Multi-Day Trips — Adventure Alan · checked August 2, 2026
- Going Light: Lightweight and Ultralight Backpacking — The Hiking Life · checked August 2, 2026