Whether the Eurostar or flying is cheaper depends on your booking window and your "hidden" costs. For 2026, Eurostar tickets from London St Pancras to Paris Gare du Nord often start around £39–£55 ($50–$70) if booked months in advance. While budget airlines might offer a "base fare" for as low as £25, you must add the costs of airport transfers (like the Heathrow Express or the train from CDG into Paris), which can easily add £40 to your trip. Additionally, Eurostar has no liquid restrictions and a much more generous luggage allowance than budget airlines. When you factor in the value of your time (city-center to city-center) and the lack of baggage fees, the Eurostar is almost always the more economical and convenient choice for a London-to-Paris trip, despite the occasionally higher "sticker price" of the ticket itself.