JourneyCalcs is a small set of travel calculators built because the existing ones kept being wrong in ways that cost money — a fuel calculator that does not ask which gallon you mean, a flight time that ignores which direction you are flying, a baggage chart with one date on it covering sixty airlines.
How the figures are checked
Baggage data is read from each airline's own published policy and dated per row. Where a carrier blocks access to its own allowance page, it is left out and named rather than filled in from somewhere else. That is why Ryanair and Air France are absent.
Where a figure comes from research rather than a policy page — jet lag adjustment rates, the flight-time model, real-world fuel consumption — the source is linked on the sources page and the reasoning is on the tool's own page.
What it cannot do
It cannot tell you what a specific gate agent will do on a specific day. Cabin bag enforcement varies by airport, by airline and by how full the flight is. The tables say what the airline publishes, which is the only thing anyone can honestly promise.
It also does not book anything, does not compare prices and has no affiliate links, which is why it can say a carrier's rules are worse without that being awkward.
Corrections
Wrong figures are the only real failure mode here. If you find one: bigolronald@gmail.com.