A free tool that answers one question — will your bag fit? — using only what each operator publishes itself.
Willitboard is a free tool that answers one question: will your bag fit? You type your bag's size and weight, and it tells you, for each airline, train and ferry it covers, whether that bag goes at no extra cost, has to be paid for, or doesn't fit — and where the operator doesn't publish a size, it shows their rule in their own words instead of guessing.
From the operator's own page, and nowhere else. Not from blogs, travel forums, luggage brands or other comparison sites, because that is exactly how out-of-date measurements spread. A person opens the official page, confirms what it says, and records the date. That page and that date are shown next to every figure, so you can check them yourself.
Willitboard is a small independent project. It is not affiliated with, sponsored by or endorsed by any airline, rail company or ferry operator. Operator names are used only to say whose rules a page describes.
Operators change their rules, sometimes without notice. If something here doesn't match what an operator publishes today, write to hello@willitboard.com with the link. It is checked against the official page, corrected, and dated like everything else.