The yellow label, and why it outranks everything else you own
Somewhere on your camper there is a yellow sticker that no brochure, no listing, and no confident stranger in a forum thread outranks. Under the federal labeling rules that apply to units built since 2008 (49 CFR 571.110 S9), the manufacturer must state on the vehicle itself how much cargo that particular unit is built to carry. That figure is its cargo carrying capacity, usually shortened to CCC, and the reason it beats any calculation you could do is straightforward: it was worked out for the trailer that actually left the assembly line wearing your serial number, with the options your unit was ordered with, rather than for the configuration the marketing department photographed.
Two consequences follow, and the calculator above is built around both. First, if you can read the label, read the label. That mode is offered first deliberately. Second, the GVWR-minus-UVW path is genuinely a fallback: a reconstruction rather than a reading, useful when the sticker is missing, illegible, painted over during a repair, or simply older than the current rules. Units predating 2008 were labeled under the earlier NCC/SCWR regime, which is a different accounting altogether, so a capacity figure copied out of a ten-year-old classified ad may not mean what a modern reader assumes it means. If you cannot find the label on your unit, ask the manufacturer where it was placed on your floorplan instead of guessing, and treat every number here as provisional until you do.
The two rules everyone gets backwards
Propane. On RVs labeled since 2008, federal rules require the weight of full propane containers to be counted inside the unit's unloaded vehicle weight. Your label's cargo number therefore already assumes the bottles are full. Owners routinely subtract propane a second time, discover a phantom shortfall, and start unpacking clothes they did not need to unpack. Some manufacturers' own glossaries still describe UVW the older way; the label on your unit follows the federal rule, and the label wins. The calculator has a field for propane you carry beyond the standard bottles (a spare cylinder in the truck bed, a larger swap) and nothing else. Enter that by pounds filled plus the empty cylinder's tare, not by gallons, because the steel is a substantial fraction of what you are lifting: a nominal "20-lb" cylinder weighs roughly 36 to 39 pounds full depending on whose tare you have, and exchange cylinders are commonly filled to about 15 pounds rather than 20.
Water. Precisely the opposite. Every gallon on board is cargo, and the yellow label carries that caution in its own words: a full load of water equals a stated number of pounds of cargo, at roughly 8.3 pounds per gallon. This page computes with 8.34 pounds per gallon, the published density figure; the label rounds. That is an engineering rounding difference, not a disagreement between authorities, and the arithmetic here rounds consumption upward so the rounding never flatters you.
Water is the heaviest thing most owners load without noticing
Nobody hesitates before flipping the fill valve. It costs nothing, it takes four minutes at the campground spigot, and it feels like the least consequential decision of the trip. It is usually the largest single line item on the whole load sheet. At 8.34 pounds per gallon, every ten gallons is 83.4 pounds, every twenty is nearly 167, and a hundred gallons of fresh water is 834 pounds — comparable to four adult passengers you did not plan on. Water is also nearly twice as heavy per gallon as propane, which is 4.24 pounds per gallon, so the tank everyone ignores outweighs the bottles everyone worries about by a wide margin.
Three habits keep this honest. Read your unit's actual tank capacities out of the owner's manual rather than estimating from the size of the hatch. Remember the water heater, which holds water whether or not you think of it as a tank, and which stays full unless you deliberately drain it. And account for the trip home: water does not evaporate out of the system, it migrates. Fresh water you drew down over a weekend has become gray water and black water sitting in tanks mounted somewhere else entirely, so a unit that started nose-heavy can finish tail-heavy at the same total weight. Emptying the waste tanks before you hitch up is the cheapest weight reduction available anywhere in this hobby, and traveling with a fresh tank you only need after arrival is the most common way to spend capacity on nothing.
Dry weight, brochure weight, and the weight of the unit you actually bought
The number in the sales literature — dry weight, shipping weight, base UVW, whatever a given brand calls it — describes a base-specification unit. Yours is not that unit. The option package, the second air conditioner, the upgraded axle, the outdoor kitchen, the fireplace, the theatre seating, the solar package, the spare tire carrier: each one was installed at the factory and each one arrived with weight attached. The unit that reached the dealer lot is heavier than the flyer, sometimes by a margin that matters more than everything you plan to pack.
This is also why UVW and automotive curb weight are not interchangeable terms even though they occupy the same conceptual slot. Curb weight, as federal definitions frame it, covers the vehicle with full fluids and standard equipment but no occupants or cargo. RV unloaded vehicle weight on a post-2008 label additionally includes full propane. Two regimes, two bases. Mixing them inside one equation produces a number that looks authoritative and means nothing. Keep each figure with the definition it came from, and never subtract a weight that one of your inputs already contains.
Everything added after the label was printed comes straight off the top
Cargo capacity is not only spent by what you pack; it is permanently reduced by what gets bolted on. The label was computed at a moment in time, and anything installed afterward is, from the label's point of view, cargo that never comes out. Solar panels and their controllers, a second or third house battery, a lithium conversion with its charger and wiring, an inverter, a generator, an upgraded suspension kit, a slide topper, a rear ladder, a bike rack, a bumper-mounted cargo box, a residential mattress swapped for the factory foam, tools and leveling blocks that live in the pass-through and are never unpacked between trips. Every one of those is a standing deduction.
The subtlety that trips people up is deciding what belongs in the "added after" field of the calculator. Factory equipment does not. Neither does anything installed before the certification label was calculated. The federal rules even contemplate this directly, with a separate provision covering weight added between a vehicle's certification and its first sale. So the practical question is not "did this come with the camper" but "was this on the unit when the label was made." And if the answer is genuinely unknown, on an older or heavily modified rig, the resolution is not a better guess. It is a scale ticket for the empty trailer, which settles the argument permanently and costs less than a tank of fuel.
Loading the front of the camper spends your truck's payload, not the camper's
Cargo capacity and tongue weight are two separate accounts, and where you set a box determines which one you draw from. Weight placed ahead of the trailer's axles increases the share of the load pressing down on the hitch — the tongue weight on a conventional trailer, the pin weight at the kingpin of a fifth-wheel. NHTSA describes tongue weight simply as the amount of the trailer's weight that presses down on the trailer hitch. That downward force does not float; it lands on the tow vehicle and is consumed out of the yellow occupants-and-cargo placard in the driver's door jamb, the same account already paying for passengers, dogs, firewood and hitch hardware.
The manufacturers state this as a constraint rather than a suggestion. Ford's guide requires that tongue load together with passengers and cargo not push the vehicle past its rear axle rating or its GVWR; GM's wording names the rear axle rating, the GVWR and the maximum tongue load in the same breath. In the RV context the federal motor-home labeling language makes the same point from the other direction: the tongue weight of a towed trailer counts as cargo. As a share of loaded trailer weight, published guidance runs about 10 to 15 percent for conventional trailers and about 15 to 25 percent for fifth-wheels and goosenecks, with authorities differing at the edges, which is exactly why this site quotes the band instead of inventing a single tidy figure.
The tempting escape hatch is to shove everything heavy toward the rear bumper and watch the tongue percentage fall. Do not. NHTSA is blunt about the consequence: too little tongue weight can cause the trailer to sway, and sway is not a comfort complaint, it is how combinations are lost. Balance is a distribution problem with a hazard at both ends, not a slider you drag until a calculator stops objecting. Run the tow-vehicle side of the arithmetic on the ratings check, and if the concept of one budget paying for several things at once is new, why payload first lays it out from the beginning.
Worked example — the defaults on this page
What this check never looked at
This page is a planning check only, and it is not permission to tow. It performs one subtraction against one capacity figure you supplied, and a total that comes out under a limit tells you nothing about how that total is arranged. It does not see individual axle loads, individual tire loads or their inflation pressures, side-to-side balance, the tongue or pin weight leaving through the hitch, brake capacity or adjustment, the structural rating of the bumper your bike rack is clamped to, or the condition of anything underneath. A rear cargo carrier can sit comfortably inside your CCC and still exceed what the frame member holding it was designed to take.
Side-to-side loading deserves its own warning, because it is the failure a truck-stop platform cannot detect. The Escapees SmartWeigh program puts it plainly: a platform scale can give a false "safe" indication when one side of the rig is overloaded, because the platform reports an axle total and says nothing about how that total splits between the wheels. Individual wheel-position weighing is the only method that answers the question. Nothing on this page answers it either.
So treat every result here the way the rest of this site is worded. There are three outcomes and none of them is a green light: over capacity, incomplete, or no overage found in the checks completed. Blank fields become "not checked," never "assumed fine." The authorities are the yellow label on your unit, its data plate, your tow vehicle's certification label and door-jamb placard, your owner's manual, and the law wherever you happen to be driving. This page is arithmetic that shows its work, and where the two disagree, the page is wrong. Estimates plan; scales measure. When it matters, take the whole outfit to a certified scale and find out.
Frequently asked questions
Does propane count against my RV's cargo capacity? For RVs labeled under the post-2008 federal rules, no: the weight of full propane tanks is included in the RV's unloaded vehicle weight, so the yellow label's cargo capacity already accounts for full propane. Fresh water is different: it counts as cargo, which is why the label carries a caution that a full load of water equals a stated number of pounds of cargo at about 8.3 pounds per gallon. Older units used different labeling rules, so always trust the label on your specific RV.
How do I find my RV's real cargo capacity? Use the cargo carrying capacity printed on your unit's own yellow label. It reflects the RV as built, including factory options. Calculate GVWR minus UVW only as a fallback, because brochure UVW figures may not match your unit as delivered. Then subtract water, gear, and anything installed after the label was made; don't re-subtract batteries or options the label already counted.