Reference data and charts
Every figure on this site, computed at build time from published constants and standard equations, gathered in one place and downloadable as CSV. Use them, check them, or tell us they are wrong.
How to use this page
Each chart below is generated from the constants and equations named in its note, not drawn by hand and not copied from another publisher. The CSV under each one contains exactly the numbers plotted, so you can reproduce the figure, extend it, or test it against your own measurements.
You are welcome to republish these figures and tables with attribution to Camp Gear Experts and a link to this page. The method behind them is set out on how we evaluate gear, and anything we get wrong is logged on the corrections page.
Computed figures
- Propane
- Isobutane
- n-Butane
Gauge pressure is what pushes fuel out of the canister. When the curve reaches zero the stove cannot draw vapour, which is why a 20 percent propane blend keeps working long after the butane fraction has stopped.
Show the underlying numbers
| Canister temperature (degrees C) | Propane | Isobutane | n-Butane |
|---|---|---|---|
| -25 | 1.08 | 0 | 0 |
| -20 | 1.5 | 0 | 0 |
| -15 | 1.99 | 0 | 0 |
| -10 | 2.54 | 0.09 | 0 |
| -5 | 3.17 | 0.31 | 0 |
| 0 | 3.87 | 0.56 | 0.03 |
| 5 | 4.66 | 0.85 | 0.24 |
| 10 | 5.54 | 1.19 | 0.48 |
| 15 | 6.51 | 1.57 | 0.75 |
| 20 | 7.58 | 2 | 1.06 |
| 25 | 8.76 | 2.48 | 1.42 |
| 30 | 10 | 3.01 | 1.81 |
Modelled as q = A x dT / R, with 0.45 square metres of contact and a 20 degree difference across the pad. The first three R-values buy most of the warmth: going from R-1 to R-2 saves 25 watts, going from R-5 to R-6 saves under 2.
Show the underlying numbers
| Pad R-value | Watts |
|---|---|
| R-0.5 | 102 |
| R-1 | 51.1 |
| R-1.5 | 34.1 |
| R-2 | 25.6 |
| R-3 | 17 |
| R-4 | 12.8 |
| R-5 | 10.2 |
| R-6 | 8.5 |
| R-7 | 7.3 |
- Comfort (standard woman)
- Limit (standard man)
- Extreme (survival only)
ISO 23537 reports comfort, limit and extreme from the same manikin run. Marketing usually prints the limit figure, which is modelled on a standard man sleeping curled up, not on comfort. The extreme figure is a survival number and should never drive a purchase.
Show the underlying numbers
| Bag | Comfort (standard woman) | Limit (standard man) | Extreme (survival only) |
|---|---|---|---|
| Comfort 10 | 10 | 4 | -8 |
| Comfort 5 | 5 | -1 | -13 |
| Comfort 0 | 0 | -6 | -18 |
| Comfort -5 | -5 | -11 | -23 |
| Comfort -10 | -10 | -16 | -28 |
Energy in the water is fixed at 377 kJ per litre (10 to 100 degrees C). Everything else is delivery efficiency. Fuel mass = 377 kJ / (efficiency x 45.8 MJ per kg).
Show the underlying numbers
| Item | grams of gas |
|---|---|
| Open burner, breezy, no lid | 37.4 |
| Open burner, still air, lid on | 24.2 |
| Burner plus windscreen | 18.3 |
| Integrated heat-exchanger pot | 13.3 |
| Heat exchanger in a cold wind | 16.5 |
- Ambient 32 C
- Ambient 25 C
- Ambient 18 C
Steady-state model: heat leak = (k / thickness) x area x temperature difference, ice melt = heat leak / 334 kJ per kg. It ignores lid openings and warm food, which in practice are the two biggest losses of all.
Show the underlying numbers
| Foam wall thickness (mm) | Ambient 32 C | Ambient 25 C | Ambient 18 C |
|---|---|---|---|
| 15 | 13.4 | 10.3 | 7.17 |
| 25 | 8.07 | 6.19 | 4.3 |
| 38 | 5.31 | 4.07 | 2.83 |
| 50 | 4.04 | 3.09 | 2.15 |
| 64 | 3.15 | 2.42 | 1.68 |
- Entry level
- Considered mid
- Light three-season
The big three (pack, shelter, sleep system) hold roughly 60 percent of base weight in every generation, which is why replacing them first is worth more than trimming the rest of the list twice over.
Show the underlying numbers
| Item group | Entry level | Considered mid | Light three-season |
|---|---|---|---|
| Pack | 2200 | 1400 | 800 |
| Shelter | 2600 | 1600 | 900 |
| Sleep bag | 1700 | 1100 | 700 |
| Sleep pad | 900 | 600 | 400 |
| Kitchen | 900 | 550 | 300 |
| Clothing | 1600 | 1100 | 800 |
| Other | 1300 | 900 | 600 |
Handheld gear lives in single-digit watt-hours. The moment a compressor fridge joins the trip the power problem changes category, which is the real dividing line between a power bank and a leisure battery.
Show the underlying numbers
| Item | Watt-hours per day |
|---|---|
| Phone, airplane mode, map at camp | 4.5 |
| Phone, navigating and photos all day | 11 |
| Headlamp, 2 h at 100 lumens | 1.6 |
| GPS watch, full-day track | 2.2 |
| Camera, one battery every two days | 7 |
| Inflating a pump sack pad electrically | 3 |
| Satellite messenger, tracking on | 5 |
| 12 V fridge, 40 L, 25 C ambient | 320 |
One clo keeps a resting adult comfortable at 21 degrees C in still air. Values are for the garment alone, measured dry and unventilated: wind and moisture cut them hard, which is why the shell in this list is worth far more than its 0.15 suggests.
Show the underlying numbers
| Item | clo |
|---|---|
| Merino base layer, 200 g/m2 | 0.35 |
| Grid fleece, 250 g | 0.55 |
| Synthetic active insulation, 60 g fill | 0.7 |
| Down sweater, 800 fill, 90 g fill | 1.4 |
| Expedition down parka, 200 g fill | 2.6 |
| Hard shell, no insulation | 0.15 |
A sleeping adult on a wide pad occupies about 0.65 m2 of floor. Anything under 1.2 m2 per person works for one night and grates by the third, which is the practical case for buying one size up.
Show the underlying numbers
| Item | square metres per person |
|---|---|
| 2-person backpacking, 2.6 m2 | 1.3 |
| 2-person, roomy 3.1 m2 | 1.55 |
| 3-person shared by 2 | 1.85 |
| 4-person family tent, 4 sleepers | 1.15 |
| 6-person family tent, 4 sleepers | 1.9 |
| 6-person cabin tent, 6 sleepers | 1.27 |
Chemical treatment is light and cheap but slow, and the long chlorine dioxide wait applies only when cryptosporidium is a real risk. Filters trade grams for immediacy.
Show the underlying numbers
| Item | minutes |
|---|---|
| Hollow fibre squeeze filter | 4 |
| Gravity filter (hands off) | 8 |
| UV pen, two 1 L doses | 3 |
| Boiling, including cool down | 25 |
| Chlorine dioxide, bacteria and virus | 30 |
| Chlorine dioxide, cryptosporidium | 240 |
Reference tables
These tables appear on more than one guide, so they are defined once and rendered everywhere from the same source. A correction to one of them lands on every page that uses it in the same update.
Comfort temperature adjustments used by our sleep system calculator
Each figure is a shift in the temperature at which a person sleeps comfortably, relative to a bag used on an adequate pad, in a tent, by a rested adult. They are additive, and they stop being reliable past about 8 degrees of total adjustment.
| Factor | Shift | Why |
|---|---|---|
| Pad R-value one step below the season need | +4 C (feels colder) | Conduction to the ground scales with 1/R and is not something a warmer bag can fix |
| Pad R-value one step above | -1.5 C | Diminishing returns once conduction is already small |
| Silk or thin liner | -1 C | Adds a still-air layer and keeps body oils off the fill |
| Fleece or thermal liner | -3 C | Real insulation, at 300 to 500 g |
| Bag one size too large for the sleeper | +2 C | Extra dead air the body has to heat |
| Sleeping in a single-wall tarp instead of a tent | +2 C | Loss of the still-air pocket and of radiant shielding |
| Vapour barrier liner, used correctly | -4 C | Stops evaporative loss from the skin, at a comfort cost |
| Hot meal and a hot drink within an hour of bed | -1 C | Raises core temperature and gives the body fuel to burn overnight |
| Going to bed dehydrated or under-fed | +3 C | The most common cause of a cold night that gets blamed on the bag |
| Damp fill after two humid nights, down | +3 to +5 C | Loft collapse, cumulative and slow to notice |
| Cold sleeper (self-identified, consistent) | +3 C | Matches the gap the ISO standard reports between its two test manikins |
What each ANSI/PLATO FL1 headlamp figure means
FL1 is the reason two headlamps can both claim 400 lumens and behave nothing alike. Every number on the box is defined, and every one of them is measured at a different moment in the burn.
| FL1 figure | Definition | What it hides |
|---|---|---|
| Light output (lumens) | Total output measured 30 to 120 seconds after switch-on, at full charge | Says nothing about output after five minutes, when thermal throttling has kicked in |
| Beam distance (m) | Distance at which the beam delivers 0.25 lux, roughly full-moon light | Full-moon light is not usable light: expect to see detail at about a third of the rated distance |
| Run time (h) | Time until output falls to 10 percent of the initial figure | A lamp can spend most of that run time at a tenth of its headline brightness |
| Peak beam intensity (candela) | Brightest point of the beam | A tight hotspot inflates it while making the lamp worse for camp tasks |
| Impact resistance (m) | Survives six drops onto concrete from the stated height | Tested without the battery bay under load, and not for repeated drops |
| Water resistance (IPX) | IPX4 splashing, IPX7 thirty minutes at one metre, IPX8 beyond | IPX ratings are tested on new seals with a clean gasket |
Waterborne threats and the treatments that actually handle them
Choosing treatment is choosing which of the three classes you are defending against. Size is what decides whether a filter can catch it.
| Class | Typical size | Filter (0.2 micron) | Chlorine dioxide | UV | Boiling |
|---|---|---|---|---|---|
| Protozoa (giardia, cryptosporidium) | 1 to 15 microns | Removed | Slow: up to 4 hours for cryptosporidium | Effective in clear water | Effective |
| Bacteria (E. coli, campylobacter, salmonella) | 0.2 to 5 microns | Removed | 30 minutes | Effective in clear water | Effective |
| Viruses (norovirus, hepatitis A, rotavirus) | 0.02 to 0.4 microns | Passes through most hollow fibre filters | 30 minutes | Effective in clear water | Effective |
| Sediment and tannins | Visible to microns | Clogs the filter, pre-filter first | No effect | Blocks UV, treat as untreated | No effect on taste |
| Dissolved chemicals, heavy metals | Molecular | Only with an activated carbon stage | No effect | No effect | Concentrates them |
Class sizes follow the ranges used in the US EPA Guide Standard and NSF/ANSI P231 microbiological purifier protocol.
Hydrostatic head figures and what they mean in weather
Hydrostatic head is the water column in millimetres a fabric holds before it leaks. It is measured on new, unflexed fabric, which is why the useful reading is the margin above what your conditions demand, not the number itself.
| Rating | Holds up to | Realistic use |
|---|---|---|
| 800 to 1,200 mm | Light, short rain | Summer festival and fair-weather tents, budget flysheets |
| 1,500 to 2,000 mm | Steady rain, moderate wind | The common three-season family tent floor and fly |
| 3,000 mm | Sustained rain, wind-driven | Serious three-season use, and the sensible minimum for a tent floor under body weight |
| 5,000 mm and above | Storm, snow load, long trips | Mountain shelters, groundsheets that live on gravel |
| 10,000 mm plus | Marketing territory | Beyond about 5,000 mm the seams, the pitch and the floor, not the fabric, decide whether you stay dry |
Test method: ISO 811 (hydrostatic pressure test). Kneeling on a tent floor generates roughly 2,000 mm of local pressure, which is why floors are rated higher than flysheets.
How often gear actually needs cleaning or re-treating
Under-washing is the more common failure. Body oils and salt kill loft and wet out shells long before abrasion does.
| Item | Clean when | Treatment | Storage |
|---|---|---|---|
| Down sleeping bag | Loft drops, or every 20 to 30 nights of use | Down-specific wash, front loader, three dryer cycles with balls | Uncompressed in a large cotton or mesh sack, dry, off the floor |
| Synthetic bag | Every 15 to 25 nights | Mild technical wash, low tumble | Loose, uncompressed |
| Rain shell | When water stops beading, roughly every 10 to 15 days of wear | Technical wash, then heat to reactivate DWR, re-treat if beading does not return | Hung, unzipped |
| Down jacket | Every 20 to 40 wears, or after a sweaty trip | Same as a down bag, but watch the hood baffles for clumping | Hung or loosely boxed |
| Tent | After every coastal, sandy or muddy trip | Sponge with cold water, never machine wash, never detergent on the coating | Bone dry, loosely folded on new lines each time |
| Water filter | Backflush every fill day, deep clean each trip | Manufacturer backflush, then dry fully before storing | Dry, and never below freezing once wet |
| Stove | When the flame goes yellow or uneven | Clear the jet, check the O-ring, service the pump cup on liquid fuel stoves | O-rings lightly oiled, fuel bottle empty |