Skip to content
Tom's HikingTom’s Hiking

Trail terms

Zero day

Also called zero

What is a zero day?

A zero day is a day on a long trail where you walk no trail miles at all, usually taken in a town to rest, resupply and deal with logistics. A nero is a near-zero: a handful of miles into or out of town with the rest of the day off.

Zero day at a glance

Zero
No trail miles
Nero
A few miles, mostly off
Typical rhythm
Roughly one a week once fit

What a zero is actually for

Rest is only part of it. A zero is when the laundry gets done, the resupply box gets sorted, the blown-out shoes get replaced, the permit gets sorted and the injury gets looked at. Hikers who take none of them tend to end their trip on an overuse injury rather than a decision.

The other half is psychological, and experienced thru-hikers are blunt about it: the trips that fail usually fail in someone's head before they fail in their legs. A day off in a town where you eat properly and sleep in a bed resets a great deal.

What it does to your pack

Zeros and neros are the thing that sets how much food you carry, which is the largest variable in total pack weight. A schedule with frequent town stops means short carries and a small pack. A remote stretch with no resupply for a week means eight or nine pounds of food alone, and a pack with the volume and the frame to take it.

This is why base weight is quoted separately from what you actually carry. Base weight is a property of your kit and does not change; the food on top of it swings by many pounds depending on where the next town is.

What this means when you're choosing

  • Pack volume and load rating that cover your longest carry, not your average one
  • Resupply spacing on your route, which sets food weight more than anything else does

The common mistake

Treating zeros as lost days

Hikers new to long trails often push through and skip them, then lose a week to a tendon. The days off are what let the days on continue, and almost every successful long-trail schedule has them built in from the start rather than taken in an emergency.

Common questions

What is the difference between a zero and a nero?

A zero is no trail miles at all. A nero is a near-zero: a few miles into or out of town with most of the day spent off trail. Neros are more common because they still move you forward.

How often should you take a zero?

There is no rule, and it depends on your mileage and your body. Many long-trail hikers settle into roughly one a week once they are in shape, and take more early on while their legs are still adapting.

Where this is defined

Where this comes up

Guides on Tom's Hiking where zero day changes which product is right for you.

More in trail terms

Base weight

Base weight is everything in your pack except food, water and fuel: the gear that doesn't get used up. It's the number backpackers compare, because consumables vary with trip length while base weight is a property of your kit.

Ultralight

Ultralight is a style of backpacking built around a base weight under 10 lb. It gets there by making the big three lighter and by carrying fewer things, which trades comfort in camp and margin in bad conditions for comfort while walking.

Fastpacking

Fastpacking is covering a multi-day route with a pack light enough to run in, somewhere between trail running and ultralight backpacking. Typical loads run 8 to 20 liters, and the trip is usually run downhill and on the flat and hiked uphill.

Thru-hiking

Thru-hiking is walking a long trail end to end in one continuous trip, usually within a single season. The Appalachian Trail, Pacific Crest Trail and Continental Divide Trail are the best-known examples in the US, each taking several months.

Shoulder season

The shoulder seasons are spring and autumn, the months either side of settled summer conditions. Days can be warm and nights near freezing, weather changes faster, and gear that works in July is often not enough in late September.

Three-season

Three-season gear is built for spring, summer and autumn but not sustained winter conditions. It's the default rating for most backpacking equipment, and in practice it means handling rain, wind and light frost but not deep snow.

Layering system

A layering system is the practice of combining a moisture-moving base layer, an insulating mid layer and a protective shell, so you can regulate temperature by adding and removing pieces rather than relying on one heavy garment.

Nero day

A nero day, short for nearly zero, is a day on a long trail when you hike only a few miles and spend the rest of it resting or doing town chores. It sits between a full hiking day and a zero day, when you hike no miles at all.

Cowboy camping

Cowboy camping is sleeping outside with no shelter over you: a pad, a bag or quilt, and the sky. It saves the weight and the time of pitching a tent, and it trades away protection from rain, wind, dew, insects and anything that walks past in the night.

Postholing

Postholing is breaking through soft snow with each step and sinking to your shin, knee or thigh, leaving a line of holes behind you. It is exhausting, it can drop your pace to under a mile an hour, and it damages the trail for everyone following.

Slickrock

Slickrock is bare, exposed sandstone with no soil on it and no tread cut into it. You walk on the rock itself and follow cairns rather than a path. Dry sandstone gives excellent grip; wet or dusty sandstone gives very little, which is where the name misleads people.

Trailhead

A trailhead is the designated access point where a trail begins, and usually where you park and start walking. Many have a map board, signs or a toilet. The US Forest Service draws a firm line: a plain junction of two trails, or of a trail and a road, is not a trailhead.

Treeline

Treeline is the elevation, or latitude, above which trees can no longer grow. It is less a line than a zone where trees shrink into stunted, wind-shaped growth, and it sits at very different heights: between 5,000 and 6,000 feet in Washington's Olympics, and above 10,000 in the Sierra.

Backcountry

Backcountry is undeveloped land away from roads and drive-in campgrounds, reached on foot or by water. In US parks it is the opposite of frontcountry, where you drive to a campground, and camping there often needs a permit. It is not the same as legally designated Wilderness.

Big three

The big three are a backpacker's shelter, sleep system and pack: the three items where most of a kit's weight sits and, as REI puts it, where you can cut the most. The usual advice is to lighten the shelter and sleep system first and choose the pack last.

Section hiking

Section hiking is completing a long trail in pieces, one stretch at a time over separate trips, rather than in one continuous push. The Appalachian Trail Conservancy counts anyone who finishes the whole trail in more than 12 months as a section hiker, and recognizes them as 2,000-milers alongside thru-hikers.

NOBO and SOBO

NOBO and SOBO are thru-hiker shorthand for northbound and southbound, the direction someone walks a long trail. On the Appalachian Trail a NOBO starts at Springer Mountain in Georgia and finishes at Katahdin in Maine, and a SOBO walks the same 2,000-plus miles the other way.

Slackpacking

Slackpacking is hiking a stretch of a long trail with only a daypack while someone else moves the rest of your gear, usually a shuttle that drops you at one road crossing and collects you at the next. You still walk every mile; you just sleep indoors and carry less.

Naismith's rule

Naismith's rule estimates how long a hike will take: one hour for every three miles of distance, plus one hour for every 2,000 feet of climbing. A Scottish mountaineer wrote it in 1892 for fit walkers taking short halts, so most people need longer.

By Tom · Last reviewed . Back to the glossary