Camping gear glossary
89 terms, standards and units that appear on gear labels, defined in the way they are actually used, with the number ranges that matter.
A
Air pad
A sleeping pad inflated by mouth or pump sack, with internal baffles and often a reflective film layer. Best warmth-to-weight and packed size of any pad type, and the only type that can fail completely in the field.
More: Sleeping pad R-value, and the heat you lose to the ground
ANSI/PLATO FL1
The flashlight standard that defines how lumens, beam distance, run time, impact resistance and water resistance are measured. Run time is measured to the point where output falls to 10 percent of the initial figure, which is why a lamp can be rated at 200 hours and be dim for 190 of them.
More: Headlamps and the FL1 standard: reading the box honestly
ASTM F3340
The test method that standardised sleeping pad R-value in 2020. A guarded hot plate measures heat flow through the pad at a fixed temperature difference. Before it existed, brands measured R-value however they liked, so pre-2020 numbers are not comparable with current ones.
More: Sleeping pad R-value, and the heat you lose to the ground
B
Base weight
The weight of everything in and on your pack except food, water and fuel. It is the only pack figure that stays constant across a trip, which is why gear discussions use it. Typical three-season figures: 9 to 12 kg entry level, 6 to 8 kg considered, under 5 kg light.
More: Base weight, explained properly, and what to cut first
Bathtub floor
A tent floor whose waterproof fabric curves up the sides for 10 to 20 cm before meeting the walls, so that ground water has no seam at ground level to find. The height of the bathtub matters more than the floor rating in real rain.
Bear canister
A hard-sided food container, required in many parks. Typically 2.5 to 4 L per person per day of food capacity, 1.0 to 1.4 kg empty, and it doubles as a camp stool and the only truly rodent-proof storage you own.
More: The car camping checklist, and how to build one you trust
Bivy bag
A weatherproof sleeve for a sleeping bag. Adds roughly 1 to 2 degrees C of warmth and blocks wind and spindrift, at the cost of condensation against the bag and no room to sit up.
More: Tent, tarp or hammock: matching shelter to terrain and skill
Boil time
A stove marketing figure, usually for 500 ml of water in still air at 20 degrees C with the manufacturer pot. It says little about fuel efficiency: a stove can boil fast by burning hard. Compare grams of fuel per litre instead.
More: How much stove fuel to carry, worked from the energy up
Box baffle
A vertical fabric wall sewn between the inner and outer shells of a down bag or jacket, creating a chamber with full loft. Cheaper sewn-through construction pinches the insulation to zero at every seam, which is a cold spot in every stitch line.
More: Down or synthetic: choosing insulation by trip, not by loyalty
Bug mesh
No-see-um netting, typically 0.6 to 1 mm apertures. Finer mesh stops smaller insects and cuts airflow, which is a direct trade against condensation in humid conditions.
More: Tent condensation: where the water comes from, and how to stop it
C
Calorie density
Calories per gram of food. The single strongest lever on food bag weight. Working range for trail food is 4.0 to 5.5 kcal per gram: below 4.0 you are carrying water and packaging, above 5.5 the menu is mostly fat and sugar.
More: Camp food calculator
Camp cot
A raised sleeping platform. Comfortable and easy on the back, and colder than the ground at the same temperature unless you insulate above it, because air circulates freely underneath.
More: Camp comfort: chairs, tables, shade and what is worth the space
Canister stove
A stove that screws onto a sealed cartridge of pressurised isobutane and propane. Simple and clean, but output falls as the canister cools and empties, and pure butane blends stop flowing near 0 degrees C.
More: Camping stove types compared, by what each one is actually good at, Canister stoves in the cold: pressure, blends and what actually works
Clo
A unit of clothing insulation. One clo keeps a resting adult comfortable at 21 degrees C in still air, and equals 0.155 square metre kelvin per watt. A grid fleece is roughly 0.55 clo, an expedition down parka around 2.6.
More: The layering system, derived from your own heat balance
Closed-cell foam pad
A folding or rolling foam mat, typically R-1.5 to R-2.5 at 300 to 450 g. Cannot puncture, works as a seat and a splint, and stacked under an air pad it adds its full R-value to the total.
More: Sleeping pad R-value, and the heat you lose to the ground
Cold soak
Rehydrating food in cold water in a sealed jar instead of cooking it, to leave the stove and fuel at home. Works with couscous, instant potato, ramen and refried beans; fails with most pasta and rice.
More: Camping stove types compared, by what each one is actually good at
Comfort rating
Under ISO 23537, the temperature at which a standard adult woman sleeps comfortably in a relaxed posture. This is the number to buy on. Marketing usually prints the lower limit figure instead.
Condensation
Water vapour from breath, sweat and the ground turning to liquid on a surface below the dew point. A sleeping adult releases roughly 40 to 70 g of water an hour, which is where the puddle inside a sealed tent comes from.
More: Tent condensation: where the water comes from, and how to stop it
Cottage brand
A small manufacturer, often making to order, typically in ultralight shelters, packs and quilts. Usually offers materials and cuts the large brands will not risk, with longer lead times and no retail returns network.
More: Base weight, explained properly, and what to cut first
Cuben fibre
The old name for Dyneema Composite Fabric, a non-woven laminate of Dyneema fibres between polyester films. Waterproof without coating, very light, does not stretch, does not like abrasion or repeated tight folding.
D
Denier
The mass in grams of 9,000 metres of a yarn. It describes yarn thickness, not fabric strength: a 20D ripstop nylon can outlast a 40D fabric with a worse weave or coating. Tent flys run 7D to 40D, floors 15D to 70D, pack bodies 100D to 500D.
Dew point
The temperature at which air becomes saturated and water condenses out. When your tent fly drops below the dew point of the air inside, the inside of the fly gets wet, no matter how good the fabric is.
More: Tent condensation: where the water comes from, and how to stop it
Down fill power
The volume in cubic inches that one ounce of down lofts to under a standard weight. 550 to 650 is budget, 800 to 900 is premium. Fill power describes quality per gram, not warmth: total fill weight decides how warm the item is.
More: Down or synthetic: choosing insulation by trip, not by loyalty
Draft collar
An insulated tube around the shoulders inside a sleeping bag that seals warm air below the neck. On bags rated below about -5 degrees C its absence costs more warmth than a fill upgrade buys.
More: How to choose a sleeping bag, in the order the decisions matter
Dual-fuel stove
A liquid fuel stove that runs on both white gas and unleaded petrol. Petrol burns dirtier and clogs jets faster, but it is available at any filling station on earth, which is the point.
More: Camping stove types compared, by what each one is actually good at
DWR
Durable water repellent: a surface treatment that makes water bead and roll off a fabric face. It is not waterproofing. When DWR fails the face fabric wets out, breathability collapses and the jacket feels like it is leaking when it is not.
More: Reproofing rain gear: DWR, wetting out and when a shell is finished, Rain jackets: what breathability numbers do and do not tell you
Dyneema
Ultra high molecular weight polyethylene fibre with an outstanding strength-to-weight ratio, used in composite fabrics, cord and reinforcement. Melts at about 145 degrees C, so it must stay away from stoves and hot car interiors.
E
EN 13537
The European sleeping bag rating standard replaced by ISO 23537 in 2016. Numbers from the two are close enough to compare, but only if you compare the same category (comfort with comfort, limit with limit).
Extreme rating
Under ISO 23537, the temperature at which a standard woman is at risk of hypothermia but survives six hours. It is a survival number, sits roughly 18 degrees below the comfort rating, and should never be used to choose a bag.
F
Fast pitch
Pitching a double-wall tent as fly plus footprint plus poles, leaving the inner at home. Saves 300 to 700 g and gives a shaded, ventilated shelter for dry, bug-free nights.
More: Pitching and site selection: the routine that makes a shelter work
Fly-first pitch
A tent design where the fly can be pitched before the inner, so the inner stays dry in rain. Common in UK and European designs, rare in American ones, and worth a lot in a wet climate.
More: Pitching and site selection: the routine that makes a shelter work
Footprint
A ground sheet cut to the tent floor. It protects the floor from abrasion, not from water: a footprint that extends past the floor edge collects rain and channels it underneath you.
More: Pitching and site selection: the routine that makes a shelter work
Freestanding tent
A tent that holds its shape from poles alone, without stakes. It can be lifted and moved and pitches on rock or platforms, at a weight penalty of roughly 200 to 500 g over a trekking pole shelter of the same floor area.
Frost liner
A breathable fabric layer hung inside a single-wall or winter tent to catch frost that would otherwise fall on the sleepers when the shelter is knocked. Adds a few hundred grams, saves a soaked bag.
More: Tent condensation: where the water comes from, and how to stop it
G
Groundsheet protector
See footprint. A separate sheet under the tent floor. Its most valuable job is letting you pitch on sharp ground without inspecting every stone.
More: Pitching and site selection: the routine that makes a shelter work
Guy line
The cord that ties a tent to a stake away from the body of the shelter. Guy lines are what make a tent survive wind: an unguyed tent in a gale is a pole failure waiting to happen, whatever the pole material.
More: Tents in wind: pole geometry, guy lines and the force that breaks them
H
Hard shell
A jacket with a waterproof and breathable membrane, no insulation. Judged on hydrostatic head, breathability, hood design and how well the face fabric holds DWR under a pack strap.
More: Rain jackets: what breathability numbers do and do not tell you
Heat exchanger pot
A pot with a corrugated aluminium fin ring on its base that captures heat from the flame edge. Raises delivered efficiency from roughly 30 to 60 percent, cutting fuel use for boiling by about a third to a half.
More: How much stove fuel to carry, worked from the energy up
Hollow fibre filter
A water filter built from bundles of microporous tubes, typically rated at 0.1 or 0.2 microns. Removes protozoa and bacteria, does not remove viruses, and is destroyed by a single freeze once wet.
More: Backcountry water treatment: matching the method to the threat
Hydrostatic head
The height of a water column in millimetres that a fabric holds before it leaks, per ISO 811. Tent flys are commonly 1,500 to 5,000 mm, floors 3,000 to 10,000 mm because kneeling generates around 2,000 mm of local pressure.
More: Waterproof ratings explained: hydrostatic head, seams and what leaks first
Hypothermia
A core body temperature below 35 degrees C. Most camping cases are not extreme cold but wet clothing in wind at 5 to 12 degrees C, which is why a shell and a dry layer matter more than the coldest jacket you own.
More: The layering system, derived from your own heat balance
I
Inverted canister
Running a remote canister stove with the cartridge upside down so liquid fuel feeds a preheat tube. It sidesteps the pressure drop of cold gas and is the reason remote stoves work in winter when upright ones do not.
More: Canister stoves in the cold: pressure, blends and what actually works
ISO 23537
The international standard for sleeping bag thermal ratings. A heated manikin in a standard base layer on a standard pad produces comfort, limit and extreme temperatures. Bags without an ISO number are rated by the brand alone.
Isobutane
The main component of most camping gas canisters. Boils at -11.7 degrees C at sea level, so a canister of pure isobutane stops delivering pressure at around that temperature. Blends add propane to extend the working range.
More: Canister stoves in the cold: pressure, blends and what actually works
L
Latent heat of fusion
The energy absorbed when ice melts without changing temperature: 334 kJ per kilogram. It is the whole reason a cooler works, and the reason 5 kg of ice buys a fixed amount of cooling no matter how you arrange it.
Limit rating
Under ISO 23537, the temperature at which a standard adult man sleeps curled up on the edge of shivering for eight hours. Typically 6 degrees below the comfort rating for the same bag.
Liner
A fabric sleeve inside a sleeping bag. Silk adds about 1 degree C, fleece about 3, and both keep body oils out of the fill, which is the cheapest way to extend a bag lifespan.
More: Why you sleep cold, and the fixes ranked by what they actually buy
Load lifter
The strap running from the top of a pack frame forward to the shoulder harness, ideally at 30 to 45 degrees. It pulls the load into your back, and it only works if the pack torso length matches yours.
More: Backpack fit: torso length, hip belts and where the load goes
Loft
The thickness of insulation once shaken out. Loft, not fill weight, is what traps air and makes warmth. A down bag that has lost loft to body oils, compression or damp is measurably colder than its label.
Lumen
Total light output. Useful for comparing headlamps only alongside beam pattern and regulated run time: 100 lumens of even flood is more useful in camp than 400 lumens in a narrow hotspot.
More: Headlamps and the FL1 standard: reading the box honestly
M
Mummy bag
A tapered sleeping bag with a hood, cut close to the body to reduce the air the sleeper has to heat. Warmer per gram than a rectangular bag, and worse for people who move at night.
More: How to choose a sleeping bag, in the order the decisions matter
MVTR
Moisture vapour transmission rate, in grams of water vapour per square metre per 24 hours. Higher looks better on paper, but the test conditions vary between methods, so MVTR figures from different brands are rarely comparable.
More: Rain jackets: what breathability numbers do and do not tell you
O
Overquilt
A light quilt laid on top of a sleeping bag to add warmth for cold trips without buying a second bag. Two layers with a total 500 g of down beat one 500 g bag, because the outer layer lofts freely.
P
Pack volume
Internal capacity in litres, measured by filling with beads, which brands do inconsistently. Useful ranges: 30 to 45 L for overnight to weekend with light gear, 50 to 65 L for multi-day, 65 L plus for winter or family loads.
Pertex
A family of tightly woven, light face fabrics used on down jackets and sleeping bag shells, chosen for down proofness, low weight and air permeability rather than for waterproofing.
More: Insulated jackets: fill weight, fill power and choosing by use
Pitch lock
Any tent feature that fixes pole ends and fabric in one repeatable geometry, so the shelter pitches identically each time. Repeatability matters in wind and rain far more than a few grams of fabric.
More: Pitching and site selection: the routine that makes a shelter work
Propane
The cold weather component of canister gas blends. Holds around 3.5 bar of usable pressure at -10 degrees C, where isobutane holds almost none, which is why a 20 or 30 percent propane blend keeps a stove alive in winter.
More: Canister stoves in the cold: pressure, blends and what actually works
Pump sack
A dry bag with a valve adapter for inflating an air pad without breathing into it. Keeps moisture out of the insulation, which prevents both mould and the slow loss of warmth that follows it.
More: Storing gear between trips so it still works in five years
Q
Quilt
A sleeping bag without a back or a hood, attached to the pad instead. Saves 150 to 350 g of insulation that body weight would have crushed flat anyway, and demands a draught-free pad attachment to work.
R
R-value
Thermal resistance of a sleeping pad, measured per ASTM F3340. Roughly: R-2 for summer, R-3 to R-4 for three seasons, R-5 plus for freezing ground, R-7 plus for snow. R-values of stacked pads add together.
More: Sleeping pad R-value, and the heat you lose to the ground
Regulated output
A headlamp circuit that holds brightness steady as the battery drains, then drops sharply, instead of fading continuously. Better light for most of the burn, less warning before it ends.
More: Headlamps and the FL1 standard: reading the box honestly
RET
Evaporative resistance, the laboratory measure behind breathability claims, in square metres pascal per watt. Lower is better: under 6 is very breathable, 6 to 13 is breathable, over 20 is uncomfortable during exercise.
More: Rain jackets: what breathability numbers do and do not tell you
Ripstop
A weave with reinforcing threads at intervals, forming a visible grid that stops a tear spreading. It limits damage; it does not make a light fabric strong.
S
Seam sealing
Tape or liquid sealant applied to needle holes in a waterproof fabric. Every stitch is a hole: an unsealed 3,000 mm fly leaks at the seams long before the fabric fails.
More: The field repair kit: under 100 grams that saves trips
Self-inflating pad
Open-cell foam inside an airtight shell. Heavier and bulkier than an air pad at the same R-value, more comfortable for side sleepers, and it still insulates if punctured.
More: Sleeping pad R-value, and the heat you lose to the ground
Silnylon
Nylon impregnated with silicone on both faces. Strong, light and slippery, it stretches when wet, so a silnylon shelter needs re-tensioning after an hour of rain. Silicone-coated fabric cannot be repaired with normal tape.
More: Waterproof ratings explained: hydrostatic head, seams and what leaks first
Single-wall tent
A shelter with one waterproof layer and no separate inner. Lighter and faster to pitch, and every gram of condensation forms on the surface you touch.
More: Tent condensation: where the water comes from, and how to stop it
Sit pad
A small piece of closed-cell foam that doubles as insulation under a torso in an emergency, a seat in wet camp, a splint, and a pad-repair patch. The best grams-to-usefulness ratio in camping.
More: Base weight, explained properly, and what to cut first
Sleep system
Bag or quilt, pad, liner, sleep clothing and shelter considered as one heat balance rather than as separate purchases. The system, not the bag, determines the temperature you can sleep at.
Sleeping bag shell
The outer fabric of a bag, typically 10D to 30D nylon or polyester, sometimes with a DWR or a water-resistant membrane. Its job is to stop down escaping and to shrug off condensation from a tent wall.
More: How to choose a sleeping bag, in the order the decisions matter
Softshell
A woven, air-permeable jacket with a light face treatment. Breathes far better than a hard shell and stops light precipitation only. The right outer layer for cold, dry, high-output days.
More: The layering system, derived from your own heat balance
Stuff sack
A bag for compressing gear. Down bags should live compressed only while walking: storage compression permanently damages loft, which is why every down bag ships with a large mesh or cotton sack as well.
More: Storing gear between trips so it still works in five years
T
Taped seams
Factory-applied waterproof tape over stitch lines. Fully taped means every seam; critically taped means only the ones most likely to leak, which is a cost saving that shows up in a storm.
More: Rain jackets: what breathability numbers do and do not tell you
Thermal bridge
A path that carries heat past insulation, such as a sewn-through seam, a compressed baffle or the ground contact under a hip. Most cold nights are bridges, not insufficient fill.
More: Why you sleep cold, and the fixes ranked by what they actually buy
Thermal conductivity
How readily a material passes heat, in watts per metre kelvin. Still air is 0.026, foam insulation about 0.03, water 0.6, and wet down close to water. This one constant explains almost every wet gear failure.
More: Down or synthetic: choosing insulation by trip, not by loyalty
Torso length
The measurement from the C7 vertebra at the base of the neck to the top of the iliac crest. It, not height, decides pack size. Most adults fall between 41 and 53 cm.
More: Backpack fit: torso length, hip belts and where the load goes
Trail weight
A tent weight excluding stuff sacks, spare stakes and packaging. Compare packed weight instead, since the stakes and sacks come with you.
Trekking pole shelter
A tent or tarp pitched with poles you already carry. Saves the 200 to 400 g of a dedicated pole set and demands more skill in siting and tensioning.
More: Tent, tarp or hammock: matching shelter to terrain and skill
U
Underquilt
Insulation hung beneath a hammock, outside the fabric, where body weight cannot compress it. A hammock without one is colder than the ground at the same temperature, because moving air strips heat from below.
More: Tent, tarp or hammock: matching shelter to terrain and skill
UV treatment
Ultraviolet light that inactivates pathogens in clear water in about 90 seconds per litre. Needs batteries, needs clear water, and treats only the water in the bottle, not the threads and the cap.
More: Backcountry water treatment: matching the method to the threat
V
Vapour barrier liner
A non-breathable liner used inside a sleeping bag in deep cold to stop body moisture reaching the insulation. Worth about 4 degrees C and keeps a bag dry over a long expedition, at a cost in comfort.
More: Why you sleep cold, and the fixes ranked by what they actually buy
Vestibule
Covered space outside the tent inner, under the fly. Where boots, packs and a stove live in rain. Around 0.4 square metres per person is a workable minimum, 0.8 is comfortable.
More: Tent size calculator
W
Waterproof breathable membrane
A film with pores or a hydrophilic structure that blocks liquid water and passes vapour. It only breathes when there is a vapour pressure gradient, so it does very little in warm, humid rain.
More: Rain jackets: what breathability numbers do and do not tell you
Watt-hour
The only sensible unit for comparing batteries: multiply the printed mAh by 3.7 and divide by 1,000. A 10,000 mAh bank is 37 Wh. Airlines cap carry-on banks at 100 Wh without approval.
More: Power banks: sizing a battery from what you actually use
Wet out
What happens when a face fabric absorbs water because its DWR has failed. The membrane behind it still blocks liquid, but vapour cannot escape, so the wearer gets wet from the inside and blames the jacket.
More: Reproofing rain gear: DWR, wetting out and when a shell is finished
White gas
Refined petroleum fuel for pressurised liquid stoves. Burns hot in any temperature, meters precisely by volume, and demands maintenance, priming and care. The default for winter expeditions and long trips abroad.
More: Camping stove types compared, by what each one is actually good at
Wind chill
The equivalent still-air temperature for exposed skin in wind. It does not cool objects below air temperature, so it does not change how much fuel your stove needs, but it does change how fast you lose heat while cooking.
More: The layering system, derived from your own heat balance
Y
Yoke
The shaped panel where pack shoulder straps meet the body of the pack. A yoke that is too wide or narrow for your shoulders creates pressure points no amount of strap adjustment fixes.
More: Backpack fit: torso length, hip belts and where the load goes
Z
Zipper baffle
The insulated tube behind a sleeping bag zipper. Without it, the zip line is a 60 cm strip with no insulation at all, worth several degrees on a cold night.
More: How to choose a sleeping bag, in the order the decisions matter