About
Most of an RV's numbers are settled engineering, printed on stickers and data plates or published in a standard. RVingToolbox applies those formulas to the rig you describe, remembers it between calculators, shows the arithmetic, and says so when the gear you already own is enough.
Most RV questions with a number in them have a published answer. Watt-hours divide by watts. Payload is printed on the truck's door jamb. Propane has a known energy content, and an air conditioner's starting current is on its data plate. Where answers go wrong is in the arithmetic around those figures: a generator sized without the compressor's start, a payload check that leaves out the tongue, a solar estimate that assumes the panels are tilted toward the sun when they lie flat on the roof.
Each calculator here does one of those jobs, and all of them read the same saved rig. You enter your battery bank or your truck's payload once, and the solar, inverter, towing and trip pages start from it.
RVingToolbox is built and written by Brian Hamilton and published by Hamilton Digital Media Limited, a small UK company that also publishes puzzle games and books and the rest of the Toolbox family of calculator sites, including pools, brewing, cycling and lawns, each built the same way as this one.
I'm not an RV technician or a master electrician. I'm a software developer with an internet engineering degree and thirty years of building software, including mathematical models for sports-prediction companies, where a formula that is slightly wrong costs someone money quickly. Building calculation tools is the work, and this site applies it to RVs.
What that background covers is the part that most often goes wrong: turning a published formula into a calculator that handles the edge cases, testing it against figures worked out by hand, and showing the working so you can check it. Where a job needs hands-on skill, such as wiring a lithium conversion, fitting a weight-distribution hitch or anything involving propane lines, the page says so and points you to the people who do that work. Where a number is a starting point rather than an answer, the page says that too.
Each part of this can be checked from the page you're on.
Conductor tables from the NEC and ABYC E-11; the federal weight-label rules (49 CFR 567.4 and 571.110) for what a sticker means; manufacturer data sheets for batteries, inverters, generators, air conditioners and furnaces; NASA and NREL solar data for sun hours. Every calculator and guide ends with a numbered list of the documents it uses, linked.
Every tool that touches a battery calls the same power engine; the towing checks, the tongue-weight page and the scale-ticket page share one set of weight rules. Each formula is implemented once and the pages call it, so a correction lands everywhere it applies.
33 calculation engines run an automated test suite on every change, with expected values worked by hand from the constants: four 6 V golf-cart batteries come out to 440 Ah at 12 V; 600 W of flat-mounted solar makes about 1.9 kWh on an average day, against the 2.7 kWh that rating times sun hours suggests.
Every result has a "show the math" panel with the arithmetic and your own numbers substituted in. If a step looks wrong, you can see which one.
The engineering here isn't ours and we don't claim it. Wire sizing follows the National Electrical Code's conductor tables and the ABYC E-11 ampacity standard used for boats and RVs. Weight ratings mean what the federal rules say they mean: GVWR and axle ratings under 49 CFR 567.4, and the RV cargo-capacity label under 49 CFR 571.110, which counts full propane in the RV's own weight and treats water as cargo (the loaded-weight calculator follows it). Solar harvest uses sun hours by state with a stated derate for flat-mounted panels, and seasonal figures from NASA's POWER surface data. Propane uses 91,500 BTU per gallon and about 4.2 lb per gallon, the figures the propane industry's own technical guide prints. Battery figures, such as nominal voltage and usable depth of discharge, follow the manufacturers' data sheets, named on each page.
Our part is the implementation, the testing and the connections between tools, with the arithmetic shown on every result.
My Rig saves your RV, your truck and how you camp in your own browser's local storage. Nothing is sent to us and there are no accounts, so the privacy policy is short. A working erase-everything button lives on the privacy page.
If you find a mistake in a calculation, a formula, a chart or a fact in an article, write to [email protected]. It goes to a person. We'll fix it, and the "Updated" date under the page's title moves when we do.
Standards get revised, products change without changing their names, and every formula has assumptions, so reports from people running the tools against their own rigs are the best check the site has.
The site is paid for by affiliate links: some product links will earn a commission at no cost to you. There are no ads that follow you around, no paid reviews, no sponsored placements, and nothing gated behind a signup. The rules we hold ourselves to are written down in the affiliate disclosure, including the commitment to say so when the gear you already own is enough, which with an RV it often is.