A4 paper is a tad wider and a tad shorter than standard US paper.

I'd just cut it a little to keep the 11" and it will look a lot like A4. Yes, one of the tests I do uses pre printed A4 paper, that's how I know

You can always try to reprint it once you get to Europe, but that's what I would do. Then again, I'd try to avoid Ryan Air if at all possible, unless it was one of those next to free fares - and even then I'd think about it twice.

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