By Dana Okoro, Editorial Reviewer · Published September 14, 2026, 6:03 PM ET · Updated September 29, 2026, 6:16 PM ET
Direct Answer
Base weight is the total weight of a backpacker's gear excluding consumables — food, water, and fuel — plus the pack itself worn empty. It's the number backpackers use to compare gear setups on equal footing, since food and water weight changes daily and depends on trip length while base weight stays constant.
In plain English
Base weight is a way to compare hiking setups fairly. It's the weight of all your gear, like your tent, sleeping bag, stove and the pack itself, but not the food, water and fuel. Those get used up during a trip, so they change every day.
Think of it like weighing a car without fuel in the tank. The fuel amount depends on the trip, so it doesn't tell you much about the car. In the same way, base weight tells you about your gear choices, not about how far you're going.
Hikers use base weight to spot where they can save weight. Writing down what every item weighs usually shows that a few big things, like the tent and sleeping bag, make up most of the total. Swapping one of those often saves more than trimming lots of small things.
Base weight includes everything carried in and on the pack except food, water, and fuel: the backpack itself, shelter, sleep system, clothing carried (not worn), cook system, and any tools, electronics, or accessories. It excludes consumables because those items get used up during a trip and don't represent a fixed, repeatable weight from one trip to the next.
Backpackers generally sort base weight into three rough classes:
Traditional: above 20 lb (9 kg) — typical of packs built around durable, heavier fabrics and full-featured frames.
Lightweight: under 20 lb (9 kg) — usually reached by trimming redundant gear and choosing lighter fabrics without going fully minimalist.
Ultralight: under 10 lb (4.5 kg) — often built around a frameless or minimal-frame pack, a non-freestanding shelter, and lightweight fabrics such as Dyneema Composite Fabric (DCF) or thin high-tenacity nylon like Robic instead of heavier nylon.
Base weight is distinct from total loaded weight, which adds food, water, and fuel on top. A hiker with a 15-pound base weight heading into a remote, multi-day stretch might still carry a loaded pack near 30 pounds once several days of food and a full water supply are added.
Tracking base weight — usually with a spreadsheet listing every item's weight in ounces — is the standard way backpackers identify where to cut. Because it isolates gear choices from trip-specific variables like food quantity, base weight lets a hiker compare a traditional framed pack from a brand like Osprey or Gregory against a minimalist pack from a brand like Hyperlite Mountain Gear or Gossamer Gear on genuinely equal terms.
Who defines base weight, and where the edges blur
There's no official standard for base weight. The Appalachian Trail Conservancy defines it as pack weight with all gear, minus consumables such as food, water and fuel.1 Gossamer Gear uses the same definition and sets the common classes: lightweight under 20 pounds, ultralight under 10 pounds and superultralight under 5 pounds.2 Zpacks says ultralight is generally agreed to mean a base weight of 10 pounds or less,3 so even the ultralight line is 'under 10' in one place and '10 or less' in another.
Two details on this page are conventions rather than defined rules. First, the library definitions don't say whether clothing you're wearing counts; leaving worn clothing out is a common trail practice, so state your rule when you compare numbers with someone else. Second, 'traditional' for anything above 20 pounds is a label, not a maker's category; the sources simply define what counts as lightweight and below.
Where the weight usually hides
The Appalachian Trail Conservancy calls the pack, shelter and sleeping bag the 'big three' and says they are usually the heaviest pieces of gear.1 That's why a gear spreadsheet so often points to the same fix: a lighter shelter or sleep system saves more than cutting a spare spoon.
Real cuts can be large. ULA says its founder, Brian Frankle, went from a 25-pound to a 12-pound base weight on his Pacific Crest Trail thru-hike.4 That's a big drop, yet under the maker definitions above it lands in the lightweight class rather than ultralight, which shows how demanding the ultralight line is.
Why base weight matters for the whole trip
Base weight sets the floor for your load, and consumables stack on top. Water's density is about 1 gram per milliliter, so each liter adds about a kilogram.5 At Guadalupe Mountains, where the NPS says to carry a gallon per person per day, a three-day trip means about 24 pounds of water alone.6
Every kilogram has a cost. A 2014 study found metabolic energy use while walking rose roughly linearly with backpack load, by about 7.6 watts per extra kilogram.7 A lower base weight doesn't change the food and water you need, but it leaves more margin for them, which matters most on long dry stretches and between distant resupply points.
